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{{drugbox
{{DrugProjectFormSinglePage
| IUPAC_name = 2-methyl-1-phenylpropan-2-amine and 2-methyl-amphetamine
|authorTag=
| image = Phentermine.png
 
| image2 = Phentermine-3d-CPK.png
{{VP}}
| width = 200px
 
<!--Overview-->
 
|genericName=
 
 
 
|aOrAn=
 
a
 
|drugClass=
 
sympathomimetic amine anorectic
 
|indication=
 
exogenous Obesity
 
|hasBlackBoxWarning=
 
|adverseReactions=
 
 
 
<!--Black Box Warning-->
 
|blackBoxWarningTitle=
Title
 
|blackBoxWarningBody=
<i><span style="color:#FF0000;">ConditionName: </span></i>
 
* Content
 
<!--Adult Indications and Dosage-->
 
<!--FDA-Labeled Indications and Dosage (Adult)-->
 
|fdaLIADAdult=
 
=====Condition1=====
 
* Dosing Information
 
:* Dosage
 
=====Condition2=====
 
* Dosing Information
 
:* Dosage
 
=====Condition3=====
 
* Dosing Information
 
:* Dosage
 
=====Condition4=====
 
* Dosing Information
 
:* Dosage
 
<!--Off-Label Use and Dosage (Adult)-->
 
<!--Guideline-Supported Use (Adult)-->
 
|offLabelAdultGuideSupport=
 
=====Condition1=====
 
* Developed by:
 
* Class of Recommendation:
 
* Strength of Evidence:
 
* Dosing Information
 
:* Dosage
 
=====Condition2=====
 
There is limited information regarding <i>Off-Label Guideline-Supported Use</i> of {{PAGENAME}} in adult patients.
 
<!--Non–Guideline-Supported Use (Adult)-->
 
|offLabelAdultNoGuideSupport=
 
=====Condition1=====
 
* Dosing Information
 
:* Dosage
 
=====Condition2=====
 
There is limited information regarding <i>Off-Label Non–Guideline-Supported Use</i> of {{PAGENAME}} in adult patients.
 
<!--Pediatric Indications and Dosage-->
 
<!--FDA-Labeled Indications and Dosage (Pediatric)-->
 
|fdaLIADPed=
 
=====Condition1=====
 
* Dosing Information
 
:* Dosage
 
=====Condition2=====
 
There is limited information regarding <i>FDA-Labeled Use</i> of {{PAGENAME}} in pediatric patients.
 
<!--Off-Label Use and Dosage (Pediatric)-->
 
<!--Guideline-Supported Use (Pediatric)-->
 
|offLabelPedGuideSupport=
 
=====Condition1=====
 
* Developed by:
 
* Class of Recommendation:
 
* Strength of Evidence:
 
* Dosing Information
 
:* Dosage
 
=====Condition2=====
 
There is limited information regarding <i>Off-Label Guideline-Supported Use</i> of {{PAGENAME}} in pediatric patients.
 
<!--Non–Guideline-Supported Use (Pediatric)-->
 
|offLabelPedNoGuideSupport=
 
=====Condition1=====
 
* Dosing Information
 
:* Dosage
 
=====Condition2=====
 
There is limited information regarding <i>Off-Label Non–Guideline-Supported Use</i> of {{PAGENAME}} in pediatric patients.
 
<!--Contraindications-->
 
|contraindications=
 
*History of cardiovascular disease (e.g., coronary artery disease, stroke, arrhythmias, congestive heart failure, uncontrolled hypertension)
 
*During or within 14 days following the administration of monoamine oxidase inhibitors
 
*Hyperthyroidism
 
*Glaucoma
 
*Agitated states
 
*History of drug abuse
 
*Pregnancy
 
*Nursing
 
*Known hypersensitivity, or idiosyncrasy to the sympathomimetic amines
 
<!--Warnings-->
 
|warnings=
 
====Precautions====
 
*Coadministration with Other Drug Products for Weight Loss
:*Phentermine hydrochloride tablets are indicated only as short-term (a few weeks) monotherapy for the management of exogenous obesity. The safety and efficacy of combination therapy with phentermine and any other drug products for weight loss including prescribed drugs, over-the-counter preparations, and herbal products, or serotonergic agents such as selective serotonin reuptake inhibitors (e.g., fluoxetine, sertraline, fluvoxamine, paroxetine), have not been established. Therefore, coadministration of phentermine and these drug products is not recommended.
 
*Primary Pulmonary Hypertension
:*Primary Pulmonary Hypertension (PPH) - a rare, frequently fatal disease of the lungs - has been reported to occur in patients receiving a combination of phentermine with fenfluramine or dexfenfluramine. The possibility of an association between PPH and the use of phentermine alone cannot be ruled out; there have been rare cases of PPH in patients who reportedly have taken phentermine alone. The initial symptom of PPH is usually dyspnea. Other initial symptoms may include angina pectoris, syncope or lower extremity edema. Patients should be advised to report immediately any deterioration in exercise tolerance. Treatment should be discontinued in patients who develop new, unexplained symptoms of dyspnea, angina pectoris, syncope or lower extremity edema, and patients should be evaluated for the possible presence of pulmonary hypertension.
 
*Valvular Heart Disease
:*Serious regurgitant cardiac valvular disease, primarily affecting the mitral, aortic and/or tricuspid valves, has been reported in otherwise healthy persons who had taken a combination of phentermine with fenfluramine or dexfenfluramine for weight loss. The possible role of phentermine in the etiology of these valvulopathies has not been established and their course in individuals after the drugs are stopped is not known. The possibility of an association between valvular heart disease and the use of phentermine alone cannot be ruled out; there have been rare cases of valvular heart disease in patients who reportedly have taken phentermine alone.
 
*Development of Tolerance, Discontinuation in Case of Tolerance
:*When tolerance to the anorectant effect develops, the recommended dose should not be exceeded in an attempt to increase the effect; rather, the drug should be discontinued.
 
*Effect on the Ability to Engage in Potentially Hazardous Tasks
:*Phentermine may impair the ability of the patient to engage in potentially hazardous activities such as operating machinery or driving a motor vehicle; the patient should therefore be cautioned accordingly.
 
*Risk of Abuse and Dependence
:*Phentermine is related chemically and pharmacologically to amphetamine (d- and d/l-amphetamine) and other related stimulant drugs that have been extensively abused. The possibility of abuse of phentermine should be kept in mind when evaluating the desirability of including a drug as part of a weight reduction program. See Drug Abuse and Dependence (9) and Overdosage (10).
:*The least amount feasible should be prescribed or dispensed at one time in order to minimize the possibility of overdosage.
 
*Usage with Alcohol
:*Concomitant use of alcohol with phentermine may result in an adverse drug reaction.
 
*Use in Patients with Hypertension
:*Use caution in prescribing phentermine for patients with even mild hypertension (risk of increase in blood pressure).
 
*Use in Patients on Insulin or Oral Hypoglycemic Medications for Diabetes Mellitus
:*A reduction in insulin or oral hypoglycemic medications in patients with diabetes mellitus may be required.
 
<!--Adverse Reactions-->
 
<!--Clinical Trials Experience-->
 
|clinicalTrials=
 
*The following adverse reactions to phentermine have been identified:
 
=====Cardiovascular=====
 
Primary pulmonary hypertension and/or regurgitant cardiac valvular disease, palpitation, tachycardia, elevation of blood pressure, ischemic events.
 
=====Central Nervous System=====
 
Overstimulation, restlessness, dizziness, insomnia, euphoria, dysphoria, tremor, headache, psychosis.
 
=====Gastrointestinal=====
 
Dryness of the mouth, unpleasant taste, diarrhea, constipation, other gastrointestinal disturbances.
 
=====Allergic=====
 
Urticaria.
 
=====Endocrine=====
 
Impotence, changes in libido.
 
<!--Postmarketing Experience-->
 
|postmarketing=
 
There is limited information regarding <i>Postmarketing Experience</i> of {{PAGENAME}} in the drug label.
 
<!--Drug Interactions-->
 
|drugInteractions=
 
*Monoamine Oxidase Inhibitors
:*Use of phentermine is contraindicated during or within 14 days following the administration of monoamine oxidase inhibitors because of the risk of hypertensive crisis.
 
*Alcohol
:*Concomitant use of alcohol with phentermine may result in an adverse drug reaction.
 
*Insulin and Oral Hypoglycemic Medications
:*Requirements may be altered [see Warnings and Precautions (5.9)].
 
*Adrenergic Neuron Blocking Drugs
:*Phentermine may decrease the hypotensive effect of adrenergic neuron blocking drugs.
 
<!--Use in Specific Populations-->
 
|useInPregnancyFDA=
* '''Pregnancy Category X'''
 
*Phentermine is contraindicated during pregnancy because weight loss offers no potential benefit to a pregnant woman and may result in fetal harm. A minimum weight gain, and no weight loss, is currently recommended for all pregnant women, including those who are already overweight or obese, due to obligatory weight gain that occurs in maternal tissues during pregnancy. Phentermine has pharmacologic activity similar to amphetamine (d- and d/l-amphetamine) [see Clinical Pharmacology (12.1)]. Animal reproduction studies have not been conducted with phentermine. If this drug is used during pregnancy, or if the patient becomes pregnant while taking this drug, the patient should be apprised of the potential hazard to a fetus.
 
|useInPregnancyAUS=
* '''Australian Drug Evaluation Committee (ADEC) Pregnancy Category'''
 
There is no Australian Drug Evaluation Committee (ADEC) guidance on usage of {{PAGENAME}} in women who are pregnant.
 
|useInLaborDelivery=
There is no FDA guidance on use of {{PAGENAME}} during labor and delivery.
 
|useInNursing=
 
*It is not known if phentermine is excreted in human milk; however, other amphetamines are present in human milk. Because of the potential for serious adverse reactions in nursing infants, a decision should be made whether to discontinue nursing or to discontinue the drug, taking into account the importance of the drug to the mother.
 
|useInPed=
 
*Safety and effectiveness in pediatric patients have not been established. Because pediatric obesity is a chronic condition requiring long-term treatment, the use of this product, approved for short-term therapy, is not recommended.
 
|useInGeri=
 
*In general, dose selection for an elderly patient should be cautious, usually starting at the low end of the dosing range, reflecting the greater frequency of decreased hepatic, renal, or cardiac function, and of concomitant disease or other drug therapy.
 
*This drug is known to be substantially excreted by the kidney, and the risk of toxic reactions to this drug may be greater in patients with impaired renal function. Because elderly patients are more likely to have decreased renal function, care should be taken in dose selection, and it may be useful to monitor renal function.
 
|useInGender=
There is no FDA guidance on the use of {{PAGENAME}} with respect to specific gender populations.
 
|useInRace=
There is no FDA guidance on the use of {{PAGENAME}} with respect to specific racial populations.
 
|useInRenalImpair=
 
*Phentermine was not studied in patients with renal impairment. Based on the reported excretion of phentermine in urine, exposure increases can be expected in patients with renal impairment. Use caution when administering phentermine to patients with renal impairment.
 
|useInHepaticImpair=
There is no FDA guidance on the use of {{PAGENAME}} in patients with hepatic impairment.
 
|useInReproPotential=
There is no FDA guidance on the use of {{PAGENAME}} in women of reproductive potentials and males.
 
|useInImmunocomp=
There is no FDA guidance one the use of {{PAGENAME}} in patients who are immunocompromised.
 
<!--Administration and Monitoring-->
 
|administration=
 
* Oral
 
|monitoring=
 
There is limited information regarding <i>Monitoring</i> of {{PAGENAME}} in the drug label.
 
<!--IV Compatibility-->
 
|IVCompat=
 
There is limited information regarding <i>IV Compatibility</i> of {{PAGENAME}} in the drug label.
 
<!--Overdosage-->
 
|overdose=
 
===Acute Overdose===
 
====Signs and Symptoms====
 
*Manifestations of acute overdosage include restlessness, tremor, hyperreflexia, rapid respiration, confusion, assaultiveness, hallucinations, and panic states. Fatigue and depression usually follow the central stimulation. Cardiovascular effects include tachycardia, arrhythmia, hypertension or hypotension, and circulatory collapse. Gastrointestinal symptoms include nausea, vomiting, diarrhea and abdominal cramps. Overdosage of pharmacologically similar compounds has resulted in fatal poisoning usually terminates in convulsions and coma.
 
====Management====
 
*Management of acute phentermine hydrochloride intoxication is largely symptomatic and includes lavage and sedation with a barbiturate. Experience with hemodialysis or peritoneal dialysis is inadequate to permit recommendations in this regard. Acidification of the urine increases phentermine excretion. Intravenous phentolamine (Regitine®, CIBA) has been suggested on pharmacologic grounds for possible acute, severe hypertension, if this complicates overdosage.
 
===Chronic Overdose===
 
*Manifestations of chronic intoxication with anorectic drugs include severe dermatoses, marked insomnia, irritability, hyperactivity and personality changes. The most severe manifestation of chronic intoxications is psychosis, often clinically indistinguishable from schizophrenia.
 
<!--Pharmacology-->
 
<!--Drug box 2-->
 
|drugBox=
 
{{Drugbox
| Watchedfields = changed
| verifiedrevid = 477171245
| IUPAC_name = 2-methyl-1-phenylpropan-2-amine
| image = Phentermine00.png
| width = 200
| image2 = Phentermine000.gif
| width2 = 250
 
<!--Clinical data-->
| tradename = Adipex-p, Duromine, Metermine, Suprenza
| Drugs.com = {{drugs.com|monograph|phentermine}}
| MedlinePlus = a682187
| pregnancy_AU = B3
| pregnancy_US = X
| pregnancy_category =
| legal_AU = S4
| legal_CA = Schedule IV
| legal_US = Schedule IV
| legal_status =
| routes_of_administration = ''Medical'': [[Oral route|oral]],<br />''Recreational'': [[Oral route|oral]], [[Insufflation (medicine)|insufflation]], [[intravenous]]
 
<!--Pharmacokinetic data-->
| bioavailability = High (almost complete)<ref name = TGA/>
| protein_bound = Approximately 96.3%
| metabolism = [[Hepatic]]<ref name = TGA/>
| elimination_half-life = 25 hours, urinary pH-dependent<ref name = TGA/>
| excretion = Urinary (62-85% unchanged)<ref name = TGA/>
 
<!--Identifiers-->
| CASNo_Ref = {{cascite|correct|CAS}}
| CAS_number_Ref = {{cascite|correct|??}}
| CAS_number = 122-09-8
| CAS_number = 122-09-8
| ATC_prefix = A08
| ATC_prefix = A08
| ATC_suffix = AA01
| ATC_suffix = AA01
| ATC_supplemental = {{ATC|C01|CA11}}
| ATC_supplemental =
| PubChem = 4771
| PubChem = 4771
| DrugBank = APRD00093
| DrugBank_Ref = {{drugbankcite|correct|drugbank}}
| DrugBank = DB00191
| ChemSpiderID_Ref = {{chemspidercite|correct|chemspider}}
| ChemSpiderID = 4607
| UNII_Ref = {{fdacite|correct|FDA}}
| UNII = C045TQL4WP
| KEGG_Ref = {{keggcite|correct|kegg}}
| KEGG = D05458
| ChEBI_Ref = {{ebicite|correct|EBI}}
| ChEBI = 8080
| ChEMBL_Ref = {{ebicite|correct|EBI}}
| ChEMBL = 1574
| synonyms= α-methyl-amphetamine<br />α,α-dimethylphenethylamine
 
<!--Chemical data-->
| C=10 | H=15 | N=1
| C=10 | H=15 | N=1
| molecular_weight = 149.233 g/mol
| molecular_weight = 149.233 g/mol
| bioavailability = Peak plasma levels occur within 1 to 4.5 hours. Absorption is usually complete by 4 to 6 hours
| smiles = NC(Cc1ccccc1)(C)C
| protein_bound = Approximately 96.3%
| InChI = 1/C10H15N/c1-10(2,11)8-9-6-4-3-5-7-9/h3-7H,8,11H2,1-2H3
| metabolism = hepatic
| InChIKey = DHHVAGZRUROJKS-UHFFFAOYAL
| elimination_half-life = 16 to 31 hours
| StdInChI_Ref = {{stdinchicite|correct|chemspider}}
| pregnancy_category = C(United States); ? (Australia)
| StdInChI = 1S/C10H15N/c1-10(2,11)8-9-6-4-3-5-7-9/h3-7H,8,11H2,1-2H3
| legal_status = C-IV (US)
| StdInChIKey_Ref = {{stdinchicite|correct|chemspider}}
| routes_of_administration = Oral
| StdInChIKey = DHHVAGZRUROJKS-UHFFFAOYSA-N
| excretion = Urinary elimination
}}
}}
{{SI}}
__NOTOC__
{{CMG}}


{{Editor Help}}
<!--Mechanism of Action-->


==For patient information, please [[Phentermine (patient information)|click here]]==
|mechAction=


==Overview==
* Phentermine is a sympathomimetic amine with pharmacologic activity similar to the prototype drugs of this class used in obesity, amphetamine (d- and d/l-amphetamine). Drugs of this class used in obesity are commonly known as "anorectics" or "anorexigenics." It has not been established that the primary action of such drugs in treating obesity is one of appetite suppression since other central nervous system actions, or metabolic effects, may also be involved.


'''Phentermine''' is an [[appetite suppressant]] of the [[amphetamine]] and [[phenethylamine]] class.
<!--Structure-->


It is approved as an appetite suppressant to help reduce weight in obese patients when used short-term and combined with exercise, diet, and behavioral modification. It is typically prescribed for individuals who are at increased medical risk because of their weight and works by helping to release certain chemicals in the brain that control appetite.
|structure=


==Commercial trade names==
* Phentermine hydrochloride USP is a sympathomimetic amine anorectic. Its chemical name is a,a-dimethylphenethylamine hydrochloride. The structural formula is as follows:
*'''Adipex P''' (Immediate release)
*'''Anoxine-AM®'''
*'''Fastin®'''
*'''Ionamin®''' (Slow Release Resin, Australia)
*'''Duromine®''' (Slow Release Resin, New Zealand)
*'''Obephen®'''
*'''Obermine®'''
*'''Obestin-30®'''
*'''Phentrol®'''
*'''Pro-Fast SA'''
*'''Redusa
*'''Panbesy
*'''Phentermine Trenker'''
*'''Obenix
*'''Oby-Trim


==History==
: [[File:{{PAGENAME}}01.png|thumb|none|600px|This image is provided by the National Library of Medicine.]]
In 1959 phentermine first received approval from the FDA as an appetite suppressing drug. Phentermine hydrochloride then became available in the early 1970s. It was previously sold as Fastin® from King Pharmaceuticals for [[SmithKline Beecham]], however in 1998 it was removed from the market. Medeva Pharmaceuticals sells the name brand of phentermine called Ionamin® and Gate Pharmaceuticals sells it as Adipex-P®.  Phentermine is also currently sold as a generic. Since the drug was approved in 1959 there have been almost no clinical studies performed. The most recent study was in 1990 which combined phentermine with [[fenfluramine]] or [[dexfenfluramine]] and became known as [[Fen-Phen]].


A study was published in 1992 that Fen-Phen was more effective than diet and exercise with few side effects. However, in 1997 after 24 cases of heart valve disease in Fen-Phen users, fenfluramine and dexfenfluramine were voluntarily taken off the market at the request of the FDA. Studies later proved that nearly 30% of people taking fenfluramine or dexfenfluramine had abnormal valve findings.  The FDA did not ask manufacturers to remove phentermine from the market.  
*Phentermine hydrochloride USP is a white, odorless, hygroscopic, crystalline powder which is soluble in water and lower alcohols, slightly soluble in chloroform and insoluble in ether.


Phentermine is still available by itself in most countries, including the U.S. However, because it is similar to [[amphetamines]], individuals may develop an [[Drug addiction|addiction]] to it. Hence, it is classified as a [[controlled substance]] in many countries. Internationally, phentermine is a schedule IV drug under the [[Convention on Psychotropic Substances]].<ref>[http://www.incb.org/pdf/e/list/green.pdf Incb.org (PDF file)]</ref> In the United States, it is classified as a [[Schedule IV]] controlled substance under the [[Controlled Substances Act]].
*Phentermine hydrochloride tablets USP are available as an oral tablet containing 37.5 mg of phentermine hydrochloride USP (equivalent to 30 mg of phentermine base). Each phentermine hydrochloride tablet USP also contains the inactive ingredients microcrystalline cellulose, pregelatinized starch, anhydrous lactose, crospovidone, colloidal silicon dioxide, magnesium stearate, sucrose, corn starch and FD&C Blue #1.


==Mechanism of action==
<!--Pharmacodynamics-->
[[Image:Phentermine.jpg|frame|left]]
Phentermine, like many other prescription drugs, works with [[neurotransmitter]]s in the brain. It is a centrally-acting [[stimulant]] and is a [[structural isomer|constitutional isomer]] (not to be confused with [[stereoisomer]])  of [[methamphetamine]]. It stimulates [[neuron]] bundles to release a particular group of neurotransmitters known as [[catecholamine]]s; these include [[dopamine]], [[epinephrine]] (also known as adrenalin), and [[norepinephrine]] (noradrenaline).  The anorectic activity seen with these compounds would thus seem likely due to this effect on the [[central nervous system]], which is consistent with current knowledge about central nervous system systems and feeding behavior. This is the same [[mechanism of action]] as other stimulant appetite suppressants such as [[diethylpropion]] and [[phendimetrazine]].  The neurotransmitters signal a [[fight-or-flight response]] in the body which, in turn, puts a halt to the hunger signal. As a result, it causes a loss in appetite because the brain does not receive the hunger message.


==Dosing and administration==
|PD=
Generally, it is recommended by the [[Food and Drug Administration]] (FDA) that phentermine should be used short-term (usually interpreted as 'up to 12 weeks'), while following nonpharmacological approaches to weight loss such as healthy [[dieting]] and [[exercise]]. However, recommendations limiting its use for short-term treatment may be controversial. One reason given behind limiting its use to 12 weeks is [[drug tolerance]], whereby phentermine loses its appetite-suppressing effects after the body adjusts to the drug. On the contrary, it has been shown that phentermine did not lose effectiveness in a 36-week trial.<ref>PMID 11054601</ref>  Due to the risk of [[insomnia]], it is generally recommended that the drug be taken either before breakfast or 1-2 hours after breakfast.


==Contraindications and warnings==
There is limited information regarding <i>Pharmacodynamics</i> of {{PAGENAME}} in the drug label.
*Patients with the following '''should not use''' Phentermine:
**An [[allergy]] to any ingredient in Phentermine or other [[sympathomimetic]]s (eg, [[pseudoephedrine]])
**Are also taking [[dexfenfluramine]], [[fenfluramine]], [[furazolidone]], guanadrel, [[guanethidine]], or have taken a [[monoamine oxidase inhibitor]] (MAOI) (eg, phenelzine) in the last 14 days
**Have moderate to severe [[high blood pressure]], an overactive thyroid, [[glaucoma]], heart or blood vessel disease, or severe narrowing of the blood vessels
**Are in an agitated state, or have a history of [[substance abuse]]
*Some '''medical conditions may interact''' with Phentermine, patients with the following should consult with their doctor before using phentermine:
**Are [[pregnant]], planning to become pregnant, or are [[breast-feeding]]
**Are taking any prescription or nonprescription medicine, herbal preparation, or dietary supplement
**Have [[allergies]] to medicines, foods, or other substances
**Have a brain or spinal cord disorder, hardening of the arteries, [[high blood pressure]], [[diabetes]], or [[high cholesterol]] or lipid levels
*Some '''medicines may interact''' with Phentermine, such as the following:
**Dexfenfluramine, fenfluramine, furazolidone, or MAOIs (eg, phenelzine) because the risk of serious side effects, such as increasing headache, high blood pressure, slow heart rate, elevated temperature, or possibly fatal lung problems, may be increased
**Serotonin specific reuptake inhibitors (eg, fluoxetine) because the risk of their side effects may be increased by Phentermine
**Guanadrel or guanethidine because their effectiveness may be decreased by Phentermine


==Side effects==
<!--Pharmacokinetics-->
Generally, phentermine appears to be relatively well tolerated.<ref name=Nelson>{{cite web
| author = Nelson DL, Gehlert DR. | year = 2006 | url = http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=pubmed&dopt=Abstract&list_uids=16622292&query_hl=49&itool=pubmed_docsum
| title = Central nervous system biogenic amine targets for control of appetite and energy expenditure.
| format = HTML | work = Endocrine. 2006 Feb;29(1):49-60
| publisher = PubMed | accessdate = 6 May | accessyear = 2006}}</ref> It can produce side effects consistent with its catecholamine-releasing
properties, e.g., tachycardia (increased heart rate) and elevated blood pressure, but the incidence and magnitude of these appear to be less than with the amphetamines. Because phentermine acts through [[sympathomimetic]] pathways, the drug may increase [[blood pressure]] and [[heart rate]].  It may also cause [[palpitation]]s, restlessness, and [[insomnia]].  Additionally, phentermine has the potential to cause physical and psychological dependence.


===More Common Symptoms===
|PK=


* [[Insomnia]]
There is limited information regarding <i>Pharmacokinetics</i> of {{PAGENAME}} in the drug label.
* Increased [[blood pressure]]
* [[Irritability]]
* [[Nervousness]]
* Sense of well-being


===Less Common to Rare Symptoms===
<!--Nonclinical Toxicology-->


* [[Blurred vision]]
|nonClinToxic=
* Change in sexual desire
* Clumsiness
* [[Confusion]]
* [[Diarrhea]]
* [[Dizziness]]
* [[Dry mouth]]
* [[Headache]]
* [[Irregular heartbeat]]
* [[Nausea]] or [[vomiting]]
* [[Psychosis]]
* Skin rash or itching
* Stomach pain
* [[Tiredness]]
* Unpleasant taste


===Possible Overdose Symptoms===
There is limited information regarding <i>Nonclinical Toxicology</i> of {{PAGENAME}} in the drug label.
*[[Confusion]]
*[[Convulsions]] ([[seizures]])
*[[Dizziness]]
*Fast Breathing
*[[Fever]]
*[[Hallucination]]s
*Hostility with urge to attack
*Irregular [[blood pressure]]
*[[Irregular heartbeat]]
*[[Lightheadedness]] or [[Fainting]]
*[[Depression]], following a period of excitement
*[[Tremor]]s, Trembling, or Shaking
*Overactive Reflexes
*[[Panic]]
*[[Restlessness]]
*Severe [[nausea], [[vomiting]] or [[diarrhea]
*Stomach cramps
*[[Tiredness]] or [[Weakness]]


==References==
<!--Clinical Studies-->
{{reflist}}


==External links==
|clinicalStudies=
*[http://www.nlm.nih.gov/medlineplus/druginfo/medmaster/a682187.html MedLine Plus - Phentermine]
*[http://www.inchem.org/documents/pims/pharm/pim415.htm International Programme on Chemical Safety - Phentermine]
*[http://toxnet.nlm.nih.gov/ TOXNET]
*[http://redpoll.pharmacy.ualberta.ca/drugbank/cgi-bin/getCard.cgi?CARD=APRD00093.txt DrugBank:Phentermine]


There is limited information regarding <i>Clinical Studies</i> of {{PAGENAME}} in the drug label.


{{Phenethylamines}}
<!--How Supplied-->
{{stimulants}}
 
{{Antiobesity preparations}}
|howSupplied=
{{SIB}}
 
[[Category:Anorectics]]
*
[[Category:Phenethylamines]]
 
[[Category:Stimulants]]
<!--Patient Counseling Information-->
[[Category:Endocrinology]]
 
|fdaPatientInfo=
 
There is limited information regarding <i>Patient Counseling Information</i> of {{PAGENAME}} in the drug label.
 
<!--Precautions with Alcohol-->
 
|alcohol=
 
* Alcohol-{{PAGENAME}} interaction has not been established. Talk to your doctor about the effects of taking alcohol with this medication.
 
<!--Brand Names-->
 
|brandNames=
 
* ®<ref>{{Cite web | title =  | url =  }}</ref>
 
<!--Look-Alike Drug Names-->
 
|lookAlike=
 
* A® — B®<ref name="www.ismp.org">{{Cite web  | last =  | first =  | title = http://www.ismp.org | url = http://www.ismp.org | publisher =  | date =  }}</ref>
 
<!--Drug Shortage Status-->
 
|drugShortage=
}}
 
<!--Pill Image-->
 
{{PillImage
|fileName=No image.jpg|This image is provided by the National Library of Medicine.
|drugName=
|NDC=
|drugAuthor=
|ingredients=
|pillImprint=
|dosageValue=
|dosageUnit=
|pillColor=
|pillShape=
|pillSize=
|pillScore=
}}
 
<!--Label Display Image-->
 
{{LabelImage
|fileName={{PAGENAME}}11.png|This image is provided by the National Library of Medicine.
}}
 
{{LabelImage
|fileName={{PAGENAME}}11.png|This image is provided by the National Library of Medicine.
}}


[[de:Phentermin]]
<!--Category-->
[[fr:Phentermine]]
[[pl:Fentermina]]
[[ru:Фентермин]]
[[fi:Fentermiini]]


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Revision as of 15:51, 15 December 2014

Phentermine
Adult Indications & Dosage
Pediatric Indications & Dosage
Contraindications
Warnings & Precautions
Adverse Reactions
Drug Interactions
Use in Specific Populations
Administration & Monitoring
Overdosage
Pharmacology
Clinical Studies
How Supplied
Images
Patient Counseling Information
Precautions with Alcohol
Brand Names
Look-Alike Names

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Vignesh Ponnusamy, M.B.B.S. [2]

Disclaimer

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Overview

Phentermine is a sympathomimetic amine anorectic that is FDA approved for the {{{indicationType}}} of exogenous Obesity. Common adverse reactions include .

Adult Indications and Dosage

FDA-Labeled Indications and Dosage (Adult)

Condition1
  • Dosing Information
  • Dosage
Condition2
  • Dosing Information
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Condition3
  • Dosing Information
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Condition4
  • Dosing Information
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Off-Label Use and Dosage (Adult)

Guideline-Supported Use

Condition1
  • Developed by:
  • Class of Recommendation:
  • Strength of Evidence:
  • Dosing Information
  • Dosage
Condition2

There is limited information regarding Off-Label Guideline-Supported Use of Phentermine in adult patients.

Non–Guideline-Supported Use

Condition1
  • Dosing Information
  • Dosage
Condition2

There is limited information regarding Off-Label Non–Guideline-Supported Use of Phentermine in adult patients.

Pediatric Indications and Dosage

FDA-Labeled Indications and Dosage (Pediatric)

Condition1
  • Dosing Information
  • Dosage
Condition2

There is limited information regarding FDA-Labeled Use of Phentermine in pediatric patients.

Off-Label Use and Dosage (Pediatric)

Guideline-Supported Use

Condition1
  • Developed by:
  • Class of Recommendation:
  • Strength of Evidence:
  • Dosing Information
  • Dosage
Condition2

There is limited information regarding Off-Label Guideline-Supported Use of Phentermine in pediatric patients.

Non–Guideline-Supported Use

Condition1
  • Dosing Information
  • Dosage
Condition2

There is limited information regarding Off-Label Non–Guideline-Supported Use of Phentermine in pediatric patients.

Contraindications

  • History of cardiovascular disease (e.g., coronary artery disease, stroke, arrhythmias, congestive heart failure, uncontrolled hypertension)
  • During or within 14 days following the administration of monoamine oxidase inhibitors
  • Hyperthyroidism
  • Glaucoma
  • Agitated states
  • History of drug abuse
  • Pregnancy
  • Nursing
  • Known hypersensitivity, or idiosyncrasy to the sympathomimetic amines

Warnings

Precautions

  • Coadministration with Other Drug Products for Weight Loss
  • Phentermine hydrochloride tablets are indicated only as short-term (a few weeks) monotherapy for the management of exogenous obesity. The safety and efficacy of combination therapy with phentermine and any other drug products for weight loss including prescribed drugs, over-the-counter preparations, and herbal products, or serotonergic agents such as selective serotonin reuptake inhibitors (e.g., fluoxetine, sertraline, fluvoxamine, paroxetine), have not been established. Therefore, coadministration of phentermine and these drug products is not recommended.
  • Primary Pulmonary Hypertension
  • Primary Pulmonary Hypertension (PPH) - a rare, frequently fatal disease of the lungs - has been reported to occur in patients receiving a combination of phentermine with fenfluramine or dexfenfluramine. The possibility of an association between PPH and the use of phentermine alone cannot be ruled out; there have been rare cases of PPH in patients who reportedly have taken phentermine alone. The initial symptom of PPH is usually dyspnea. Other initial symptoms may include angina pectoris, syncope or lower extremity edema. Patients should be advised to report immediately any deterioration in exercise tolerance. Treatment should be discontinued in patients who develop new, unexplained symptoms of dyspnea, angina pectoris, syncope or lower extremity edema, and patients should be evaluated for the possible presence of pulmonary hypertension.
  • Valvular Heart Disease
  • Serious regurgitant cardiac valvular disease, primarily affecting the mitral, aortic and/or tricuspid valves, has been reported in otherwise healthy persons who had taken a combination of phentermine with fenfluramine or dexfenfluramine for weight loss. The possible role of phentermine in the etiology of these valvulopathies has not been established and their course in individuals after the drugs are stopped is not known. The possibility of an association between valvular heart disease and the use of phentermine alone cannot be ruled out; there have been rare cases of valvular heart disease in patients who reportedly have taken phentermine alone.
  • Development of Tolerance, Discontinuation in Case of Tolerance
  • When tolerance to the anorectant effect develops, the recommended dose should not be exceeded in an attempt to increase the effect; rather, the drug should be discontinued.
  • Effect on the Ability to Engage in Potentially Hazardous Tasks
  • Phentermine may impair the ability of the patient to engage in potentially hazardous activities such as operating machinery or driving a motor vehicle; the patient should therefore be cautioned accordingly.
  • Risk of Abuse and Dependence
  • Phentermine is related chemically and pharmacologically to amphetamine (d- and d/l-amphetamine) and other related stimulant drugs that have been extensively abused. The possibility of abuse of phentermine should be kept in mind when evaluating the desirability of including a drug as part of a weight reduction program. See Drug Abuse and Dependence (9) and Overdosage (10).
  • The least amount feasible should be prescribed or dispensed at one time in order to minimize the possibility of overdosage.
  • Usage with Alcohol
  • Concomitant use of alcohol with phentermine may result in an adverse drug reaction.
  • Use in Patients with Hypertension
  • Use caution in prescribing phentermine for patients with even mild hypertension (risk of increase in blood pressure).
  • Use in Patients on Insulin or Oral Hypoglycemic Medications for Diabetes Mellitus
  • A reduction in insulin or oral hypoglycemic medications in patients with diabetes mellitus may be required.

Adverse Reactions

Clinical Trials Experience

  • The following adverse reactions to phentermine have been identified:
Cardiovascular

Primary pulmonary hypertension and/or regurgitant cardiac valvular disease, palpitation, tachycardia, elevation of blood pressure, ischemic events.

Central Nervous System

Overstimulation, restlessness, dizziness, insomnia, euphoria, dysphoria, tremor, headache, psychosis.

Gastrointestinal

Dryness of the mouth, unpleasant taste, diarrhea, constipation, other gastrointestinal disturbances.

Allergic

Urticaria.

Endocrine

Impotence, changes in libido.

Postmarketing Experience

There is limited information regarding Postmarketing Experience of Phentermine in the drug label.

Drug Interactions

  • Monoamine Oxidase Inhibitors
  • Use of phentermine is contraindicated during or within 14 days following the administration of monoamine oxidase inhibitors because of the risk of hypertensive crisis.
  • Alcohol
  • Concomitant use of alcohol with phentermine may result in an adverse drug reaction.
  • Insulin and Oral Hypoglycemic Medications
  • Requirements may be altered [see Warnings and Precautions (5.9)].
  • Adrenergic Neuron Blocking Drugs
  • Phentermine may decrease the hypotensive effect of adrenergic neuron blocking drugs.

Use in Specific Populations

Pregnancy

Pregnancy Category (FDA):

  • Pregnancy Category X
  • Phentermine is contraindicated during pregnancy because weight loss offers no potential benefit to a pregnant woman and may result in fetal harm. A minimum weight gain, and no weight loss, is currently recommended for all pregnant women, including those who are already overweight or obese, due to obligatory weight gain that occurs in maternal tissues during pregnancy. Phentermine has pharmacologic activity similar to amphetamine (d- and d/l-amphetamine) [see Clinical Pharmacology (12.1)]. Animal reproduction studies have not been conducted with phentermine. If this drug is used during pregnancy, or if the patient becomes pregnant while taking this drug, the patient should be apprised of the potential hazard to a fetus.


Pregnancy Category (AUS):

  • Australian Drug Evaluation Committee (ADEC) Pregnancy Category

There is no Australian Drug Evaluation Committee (ADEC) guidance on usage of Phentermine in women who are pregnant.

Labor and Delivery

There is no FDA guidance on use of Phentermine during labor and delivery.

Nursing Mothers

  • It is not known if phentermine is excreted in human milk; however, other amphetamines are present in human milk. Because of the potential for serious adverse reactions in nursing infants, a decision should be made whether to discontinue nursing or to discontinue the drug, taking into account the importance of the drug to the mother.

Pediatric Use

  • Safety and effectiveness in pediatric patients have not been established. Because pediatric obesity is a chronic condition requiring long-term treatment, the use of this product, approved for short-term therapy, is not recommended.

Geriatic Use

  • In general, dose selection for an elderly patient should be cautious, usually starting at the low end of the dosing range, reflecting the greater frequency of decreased hepatic, renal, or cardiac function, and of concomitant disease or other drug therapy.
  • This drug is known to be substantially excreted by the kidney, and the risk of toxic reactions to this drug may be greater in patients with impaired renal function. Because elderly patients are more likely to have decreased renal function, care should be taken in dose selection, and it may be useful to monitor renal function.

Gender

There is no FDA guidance on the use of Phentermine with respect to specific gender populations.

Race

There is no FDA guidance on the use of Phentermine with respect to specific racial populations.

Renal Impairment

  • Phentermine was not studied in patients with renal impairment. Based on the reported excretion of phentermine in urine, exposure increases can be expected in patients with renal impairment. Use caution when administering phentermine to patients with renal impairment.

Hepatic Impairment

There is no FDA guidance on the use of Phentermine in patients with hepatic impairment.

Females of Reproductive Potential and Males

There is no FDA guidance on the use of Phentermine in women of reproductive potentials and males.

Immunocompromised Patients

There is no FDA guidance one the use of Phentermine in patients who are immunocompromised.

Administration and Monitoring

Administration

  • Oral

Monitoring

There is limited information regarding Monitoring of Phentermine in the drug label.

IV Compatibility

There is limited information regarding IV Compatibility of Phentermine in the drug label.

Overdosage

Acute Overdose

Signs and Symptoms

  • Manifestations of acute overdosage include restlessness, tremor, hyperreflexia, rapid respiration, confusion, assaultiveness, hallucinations, and panic states. Fatigue and depression usually follow the central stimulation. Cardiovascular effects include tachycardia, arrhythmia, hypertension or hypotension, and circulatory collapse. Gastrointestinal symptoms include nausea, vomiting, diarrhea and abdominal cramps. Overdosage of pharmacologically similar compounds has resulted in fatal poisoning usually terminates in convulsions and coma.

Management

  • Management of acute phentermine hydrochloride intoxication is largely symptomatic and includes lavage and sedation with a barbiturate. Experience with hemodialysis or peritoneal dialysis is inadequate to permit recommendations in this regard. Acidification of the urine increases phentermine excretion. Intravenous phentolamine (Regitine®, CIBA) has been suggested on pharmacologic grounds for possible acute, severe hypertension, if this complicates overdosage.

Chronic Overdose

  • Manifestations of chronic intoxication with anorectic drugs include severe dermatoses, marked insomnia, irritability, hyperactivity and personality changes. The most severe manifestation of chronic intoxications is psychosis, often clinically indistinguishable from schizophrenia.

Pharmacology

Phentermine
Clinical data
Trade namesAdipex-p, Duromine, Metermine, Suprenza
Synonymsα-methyl-amphetamine
α,α-dimethylphenethylamine
AHFS/Drugs.comMonograph
MedlinePlusa682187
Pregnancy
category
  • AU: B3
  • US: X (Contraindicated)
Routes of
administration		Medical: oral,
Recreational: oral, insufflation, intravenous
ATC code
Legal status
Legal status
Pharmacokinetic data
BioavailabilityHigh (almost complete)[1]
Protein bindingApproximately 96.3%
MetabolismHepatic[1]
Elimination half-life25 hours, urinary pH-dependent[1]
ExcretionUrinary (62-85% unchanged)[1]
Identifiers
CAS Number
PubChem CID
DrugBank
ChemSpider
UNII
KEGG
ChEBI
ChEMBL
E number{{#property:P628}}
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Chemical and physical data
FormulaC10H15N
Molar mass149.233 g/mol
3D model (JSmol)
  (verify)

Mechanism of Action

  • Phentermine is a sympathomimetic amine with pharmacologic activity similar to the prototype drugs of this class used in obesity, amphetamine (d- and d/l-amphetamine). Drugs of this class used in obesity are commonly known as "anorectics" or "anorexigenics." It has not been established that the primary action of such drugs in treating obesity is one of appetite suppression since other central nervous system actions, or metabolic effects, may also be involved.

Structure

  • Phentermine hydrochloride USP is a sympathomimetic amine anorectic. Its chemical name is a,a-dimethylphenethylamine hydrochloride. The structural formula is as follows:
This image is provided by the National Library of Medicine.
  • Phentermine hydrochloride USP is a white, odorless, hygroscopic, crystalline powder which is soluble in water and lower alcohols, slightly soluble in chloroform and insoluble in ether.
  • Phentermine hydrochloride tablets USP are available as an oral tablet containing 37.5 mg of phentermine hydrochloride USP (equivalent to 30 mg of phentermine base). Each phentermine hydrochloride tablet USP also contains the inactive ingredients microcrystalline cellulose, pregelatinized starch, anhydrous lactose, crospovidone, colloidal silicon dioxide, magnesium stearate, sucrose, corn starch and FD&C Blue #1.

Pharmacodynamics

There is limited information regarding Pharmacodynamics of Phentermine in the drug label.

Pharmacokinetics

There is limited information regarding Pharmacokinetics of Phentermine in the drug label.

Nonclinical Toxicology

There is limited information regarding Nonclinical Toxicology of Phentermine in the drug label.

Clinical Studies

There is limited information regarding Clinical Studies of Phentermine in the drug label.

How Supplied

Storage

There is limited information regarding Phentermine Storage in the drug label.

Images

Drug Images

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Package and Label Display Panel

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Patient Counseling Information

There is limited information regarding Patient Counseling Information of Phentermine in the drug label.

Precautions with Alcohol

  • Alcohol-Phentermine interaction has not been established. Talk to your doctor about the effects of taking alcohol with this medication.

Brand Names

Look-Alike Drug Names

Drug Shortage Status

Price

References

The contents of this FDA label are provided by the National Library of Medicine.

  1. ↑ 1.0 1.1 1.2 1.3
  2. ↑ Empty citation (help)
  3. ↑ "http://www.ismp.org". External link in |title= (help)


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