TENEX adverse reactions
Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Sheng Shi, M.D. [2]
Adverse Reactions
Adverse reactions noted with Tenex (guanfacine hydrochloride) are similar to those of other drugs of the central α2-adrenoreceptor agonist class: dry mouth, sedation (somnolence), weakness (asthenia), dizziness, constipation, and impotence. While the reactions are common, most are mild and tend to disappear on continued dosing.
Skin rash with exfoliation has been reported in a few cases; although clear cause and effect relationships to Tenex could not be established, should a rash occur, Tenex should be discontinued and the patient monitored appropriately.
In the dose-response monotherapy study described under CLINICAL PHARMACOLOGY, the frequency of the most commonly observed adverse reactions showed a dose relationship from 0.5 to 3 mg as follows:
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The percent of patients who dropped out because of adverse reactions are shown below for each dosage group.
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The most common reasons for dropouts among patients who received guanfacine were dry mouth, somnolence, dizziness, fatigue, weakness, and constipation.
In the 12-week, placebo-controlled, dose-response study of guanfacine administered with 25 mg chlorthalidone at bedtime, the frequency of the most commonly observed adverse reactions showed a clear dose relationship from 0.5 to 3 mg as follows:
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There were 41 premature terminations because of adverse reactions in this study. The percent of patients who dropped out and the dose at which the dropout occurred were as follows:
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Reasons for dropouts among patients who received guanfacine were: somnolence, headache, weakness, dry mouth, dizziness, impotence, insomnia, constipation, syncope, urinary incontinence, conjunctivitis, paresthesia, and dermatitis.
In a second 12-week placebo-controlled combination therapy study in which the dose could be adjusted upward to 3 mg per day in 1-mg increments at 3-week intervals, i.e., a setting more similar to ordinary clinical use, the most commonly recorded reactions were: dry mouth, 47%; constipation, 16%; fatigue, 12%; somnolence, 10%; asthenia, 6%; dizziness, 6%; headache, 4%; and insomnia, 4%.
Reasons for dropouts among patients who received guanfacine were: somnolence, dry mouth, dizziness, impotence, constipation, confusion, depression, and palpitations.
In the clonidine/guanfacine comparison described in CLINICAL PHARMACOLOGY, the most common adverse reactions noted were as follows:
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Adverse reactions occurring in 3% or less of patients in the three controlled trials of Tenex (guanfacine hydrochloride) with a diureticwere:
Cardiovascular- bradycardia, palpitations, substernal pain
Gastrointestinal- abdominal pain, diarrhea, dyspepsia, dysphagia, nausea
CNS- amnesia, confusion, depression, insomnia, libido decrease
ENT disorders- rhinitis, taste perversion, tinnitus
Eye disorders- conjunctivitis, iritis, vision disturbance
Musculoskeletal- leg cramps, hypokinesia
Respiratory- dyspnea
Dermatologic- dermatitis, pruritus, purpura, sweating
Urogenital- testicular disorder, urinary incontinence
Other- malaise, paresthesia, paresis
Adverse reaction reports tend to decrease over time. In an open-label trial of one year's duration, 580 hypertensive subjects were given guanfacine, titrated to achieve goal blood pressure, alone (51%), with diuretic(38%), with beta blocker (3%), with diureticplus beta blocker (6%), or with diureticplus vasodilator (2%). The mean daily dose of guanfacine reached was 4.7 mg.
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There were 52 (8.9%) dropouts due to adverse effects in this 1-year trial. The causes were: dry mouth (n = 20), weakness (n = 12), constipation (n = 7), somnolence (n = 3), nausea (n = 3), orthostatic hypotension (n = 2), insomnia (n = 1), rash (n = 1), nightmares (n = 1), headache (n = 1), and depression (n = 1).
Postmarketing Experience
An open-label postmarketing study involving 21,718 patients was conducted to assess the safety of Tenex (guanfacine hydrochloride) 1 mg/day given at bedtime for 28 days. Tenex was administered with or without other antihypertensive agents. Adverse events reported in the postmarketing study at an incidence greater than 1% included dry mouth, dizziness, somnolence, fatigue, headache and nausea. The most commonly reported adverse events in this study were the same as those observed in controlled clinical trials.
Less frequent, possibly Tenex-related events observed in the postmarketing study and/or reported spontaneously include:
BODY AS A WHOLE asthenia, chest pain, edema, malaise, tremor
CARDIOVASCULAR bradycardia, palpitations, syncope, tachycardia
CENTRAL NERVOUS SYSTEM paresthesias, vertigo
EYE DISORDERS blurred vision
GASTROINTESTINAL SYSTEM abdominal pain, constipation, diarrhea, dyspepsia
LIVER AND BILLIARY SYSTEM abnormal liver function tests
MUSCULO-SKELETAL SYSTEM arthralgia, leg cramps, leg pain, myalgia
PSYCHIATRIC agitation, anxiety, confusion, depression, insomnia, nervousness
RREPRODUCTIVE SYSTEM, Male- impotence
RESPIRATORY SYSTEM dyspnea
SKIN AND APPENDAGES alopecia, dermatitis, exfoliative dermatitis, pruritus, rash
SPECIAL SENSES alterations in taste
URINARY SYSTEM nocturia, urinary frequency
Rare, serious disorders with no definitive cause and effect relationship to Tenex have been reported spontaneously and/or in the postmarketing study. These events include acute renal failure, cardiac fibrillation, cerebrovascular accident, congestive heart failure, heart block, and myocardial infarction.[1]
References
- ↑ "TENEX (GUANFACINE HYDROCHLORIDE) TABLET [PROMIUS PHARMA, LLC]". Retrieved 25 February 2014.