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GUANFACINE HYDROCHLORIDE- guanfacine tablet AvPAK
Guanfacine Tablets, USP Rx only Full Prescribing Information DESCRIPTION Guanfacine hydrochloride, USP is a centrally acting antihypertensive with α - adrenoceptor agonist properties in tablet form for oral administration. The chemical name of guanfacine hydrochloride, USP is N-amidino-2-(2,6-dichlorophenyl) acetamide hydrochloride and its molecular weight is 282.56. Its structural formula is: Guanfacine hydrochloride, USP is a white to off-white powder; sparingly soluble in water and alcohol and slightly soluble in acetone. Each tablet, for oral administration, contains guanfacine hydrochloride, USP equivalent to 1 mg or 2 mg guanfacine. In addition, each tablet contains the following inactive ingredients: microcrystalline cellulose, pregelatinized starch, and stearic acid. CLINICAL PHARMACOLOGY Guanfacine hydrochloride is an orally active antihypertensive agent whose principal mechanism of action appears to be stimulation of central α -adrenergic receptors. By stimulating these receptors, guanfacine reduces sympathetic nerve impulses from the vasomotor center to the heart and blood vessels. This results in a decrease in peripheral vascular resistance and a reduction in heart rate. The dose-response relationship for blood pressure and adverse effects of guanfacine given once a day as monotherapy has been evaluated in patients with mild to moderate hypertension. In this study patients were randomized to placebo or to 0.5 mg, 1 mg, 2 mg, 3 mg or 5 mg of guanfacine. Results are shown in the following table. A useful effect was not observed overall until doses of 2 mg were reached, although responses in white patients were seen at 1 mg; 24 hour effectiveness of 1 mg to 3 mg doses was documented using 24 hour ambulatory monitoring. While the 5 mg dose added an increment of effectiveness, it caused an unacceptable increase in adverse reactions. Mean Changes (mm Hg) from Baseline in Seated Systolic and Diastolic Blood Pressure for Patients Completing 4 to 8 Weeks of Treatment with Guanfacine Monotherapy 2 2
Mean Change S/D Seate* d n= (range) Placebo 0.5 mg 1 mg 2 mg 3 mg 5 mg White Patients Black Patients 11 to 30 8 to 28
- S/D = Systolic/diastolic blood pressure Controlled clinical trials in patients with mild to moderate hypertension who were receiving a thiazide-type diuretic have defined the dose-response relationship for blood pressure response and adverse reactions of guanfacine given at bedtime and have shown that the blood pressure response to guanfacine can persist for 24 hours after a single dose. In the 12-week placebo-controlled dose-response study, patients were randomized to placebo or to doses of 0.5, 1, 2 and 3 mg of guanfacine, in addition to 25 mg chlorthalidone, each given at bedtime. The observed mean changes from baseline, tabulated below, indicate the similarity of response for placebo and the 0.5 mg dose. Doses of 1, 2 and 3 mg resulted in decreased blood pressure in the sitting position with no real differences among the three doses. In the standing position, there was some increase in response with dose. Mean Decreases (mm Hg) in Seated and Standing Blood Pressure for Patients Treated with Guanfacine in Combination with Chlorthalidone Mean Change n = Placebo 63 0.5 mg 63 1 mg 64 2 mg 58 3 mg 59 S/D* Seated S/D* Standing
- S/D = Systolic/diastolic blood pressure While most of the effectiveness of guanfacine in combination (and as monotherapy in white patients) was present at 1 mg, adverse reactions at this dose were not clearly distinguishable from those associated with placebo. Adverse reactions were clearly present at 2 and 3 mg (see ADVERSE REACTIONS ). In a second 12-week placebo-controlled study of 1, 2 or 3 mg of guanfacine hydrochloride administered with 25 mg of chlorthalidone once daily, a significant decrease in blood pressure was maintained for a full 24 hours after dosing. While there was no significant difference between the 12 and 24 hour blood pressure readings, the fall in blood pressure at 24 hours was numerically smaller, suggesting possible escape of blood pressure in some patients and the need for individualization of therapy. In a double-blind, randomized trial, either guanfacine or clonidine was given at recommended doses with 25 mg chlorthalidone for 24 weeks and then abruptly discontinued. Results showed equal degrees of blood pressure reduction with the two drugs and there was no tendency for blood pressures to increase despite maintenance of the same daily dose of the two drugs. Signs and symptoms of rebound phenomena
of guanfacine hydrochloride as the drug is poorly dialyzed. INDICATIONS & USAGE Guanfacine tablets, USP are indicated in the management of hypertension. Guanfacine may be given alone or in combination with other antihypertensive agents, especially thiazide-type diuretics. CONTRAINDICATIONS Guanfacine tablets, USP are contraindicated in patients with known hypersensitivity to guanfacine hydrochloride, USP. PRECAUTIONS GENERAL Like other antihypertensive agents, guanfacine hydrochloride should be used with caution in patients with severe coronary insufficiency, recent myocardial infarction, cerebrovascular disease, or chronic renal or hepatic failure. Sedation Guanfacine, like other orally active central α -adrenergic agonists, causes sedation or drowsiness, especially when beginning therapy. These symptoms are dose-related (see ADVERSE REACTIONS ). When guanfacine is used with other centrally active depressants (such as phenothiazines, barbiturates, or benzodiazepines), the potential for additive sedative effects should be considered. Rebound Abrupt cessation of therapy with orally active central α -adrenergic agonists may be associated with increases (from depressed on-therapy levels) in plasma and urinary catecholamines, symptoms of “nervousness and anxiety” and, less commonly, increases in blood pressure to levels significantly greater than those prior to therapy. Information for Patients Patients who receive guanfacine should be advised to exercise caution when operating dangerous machinery or driving motor vehicles until it is determined that they do not become drowsy or dizzy from the medication. Patients should be warned that their tolerance for alcohol and other CNS depressants may be diminished. Patients should be advised not to discontinue therapy abruptly. Laboratory Tests In clinical trials, no clinically relevant laboratory test abnormalities were identified as causally related to drug during short-term treatment with guanfacine hydrochloride. Drug Interactions The potential for increased sedation when guanfacine is given with other CNS- 2 2
depressant drugs should be appreciated. The administration of guanfacine concomitantly with a known microsomal enzyme inducer (phenobarbital or phenytoin) to two patients with renal impairment reportedly resulted in significant reductions in elimination half-life and plasma concentration. In such cases, therefore, more frequent dosing may be required to achieve or maintain the desired hypotensive response. Further, if guanfacine is to be discontinued in such patients, careful tapering of the dosage may be necessary in order to avoid rebound phenomena (see Rebound above). Anticoagulants Ten patients who were stabilized on oral anticoagulants were given guanfacine, 1 to 2 mg/day, for 4 weeks. No changes were observed in the degree of anticoagulation. In several well-controlled studies, guanfacine was administered together with diuretics with no drug interactions reported. In the long-term safety studies, guanfacine was given concomitantly with many drugs without evidence of any interactions. The principal drugs given (number of patients in parentheses) were: cardiac glycosides (115), sedatives and hypnotics (103), coronary vasodilators (52), oral hypoglycemics (45), cough and cold preparations (45), NSAIDs (38), antihyperlipidemics (29), antigout drugs (24), oral contraceptives (18), bronchodilators (13), insulin (10) and beta blockers (10). Drug/Laboratory Test Interactions No laboratory test abnormalities related to the use of guanfacine hydrochloride have been identified. Carcinogenesis, Mutagenesis, Impairment of Fertility No carcinogenic effect was observed in studies of 78 weeks in mice at doses more than 150 times the maximum recommended human dose and 102 weeks in rats at doses more than 100 times the maximum recommended human dose. In a variety of test models, guanfacine was not mutagenic. No adverse effects were observed in fertility studies in male and female rats. Pregnancy Category B Administration of guanfacine to rats at 70 times the maximum recommended human dose and to rabbits at 20 times the maximum recommended human dose resulted in no evidence of harm to the fetus. Higher doses (100 and 200 times the maximum recommended human dose in rabbits and rats respectively) were associated with reduced fetal survival and maternal toxicity. Rat experiments have shown that guanfacine crosses the placenta. There are, however, no adequate and well-controlled studies in pregnant women. Because animal reproduction studies are not always predictive of human response, this drug should be used during pregnancy only if clearly needed. Labor and Delivery Guanfacine hydrochloride is not recommended in the treatment of acute hypertension associated with toxemia of pregnancy. There is no information available on the effects of guanfacine on the course of labor and delivery.
(24), oral contraceptives (18), bronchodilators (13), insulin (10) and beta blockers (10). Drug/Laboratory Test Interactions No laboratory test abnormalities related to the use of guanfacine hydrochloride have been identified. ADVERSE REACTIONS Adverse reactions noted with guanfacine hydrochloride are similar to those of other drugs of the central α -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 guanfacine could not be established, should a rash occur, guanfacine 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: Adverse Reaction Placebo n= 0.5 mg n= 1 mg n= 2 mg n= 3 mg n= Dry Mouth 0% 10% 10% 42% 54% Somnolence 8% 5% 10% 13% 39% Asthenia 0% 2% 3% 7% 3% Dizziness 8% 12% 2% 8% 15% Headache 8% 8% 13% 7% 3% Impotence 0% 0% 0% 7% 3% Constipation 0% 2% 0% 5% 15% Fatigue 2% 2% 5% 8% 10% The percent of patients who dropped out because of adverse reactions are shown below for each dosage group. Placebo 0.5 mg 1 mg 2 mg 3 mg Percent Dropouts
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: 2
Adverse Reactions Placebo n= 0.5 mg n= 1 mg n= 2 mg n= 3 mg n= Dry Mouth 5 (7%) 4 (5%) 6 (8%) 8 (11%) 20 (28%) Somnolence 1 (1%) 3 (4%) 0 (0%) 1 (1%) 10 (14%) Asthenia 0 (0%) 2 (3%) 0 (0%) 2 (2%) 7 (10%) Dizziness 2 (2%) 1 (1%) 3 (4%) 6 (8%) 3 (4%) Headache 3 (4%) 4 (3%) 3 (4%) 1 (1%) 2 (2%) Impotence 1 (0%) 1 (0%) 0 (0%) 1 (1%) 3 (4%) Constipation 0 (0%) 1 (0%) 0 (0%) 1 (1%) 1 (1%) Fatigue 3 (3%) 0 (0%) 2 (3%) 5 (6%) 3 (4%) 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: Dose Placebo 0.5 mg 1 mg 2 mg 3 mg Percent Dropouts
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: Adverse Reactions Guanfacine (n=279) Clonidine (n=278) Dry Mouth 30 % 37% Somnolence 21% 35% Dizziness 11% 8% Constipation 10% 5% Fatigue 9% 8% Headache 4% 4% Insomnia 4% 3%
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 guanfacine-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 Biliary System: abnormal liver function tests
- Musculo-Skeletal System: arthralgia, leg cramps, leg pain, myalgia
- Psychiatric: agitation, anxiety, confusion, depression, insomnia, nervousness
- Reproductive 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 guanfacine 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. To report SUSPECTED ADVERSE REACTIONS, contact AvKARE, Inc. at 1-855- 361-3993; email drugsafety@avkare.com; or FDA at 1-800-FDA-1088 or www.fda.gov/medwatch. DRUG ABUSE AND DEPENDENCE No reported abuse or dependence has been associated with the administration of guanfacine hydrochloride. OVERDOSAGE Signs and Symptoms Drowsiness, lethargy, bradycardia and hypotension have been observed following overdose with guanfacine. A 25-year-old female intentionally ingested 60 mg. She presented with severe drowsiness and bradycardia of 45 beats/minute. Gastric lavage was performed and an infusion of isoproterenol (0.8 mg in 12 hours) was administered. She recovered quickly and without sequelae.
A 28-year-old female who ingested 30 to 40 mg developed only lethargy, was treated with activated charcoal and a cathartic, was monitored for 24 hours, and was discharged in good health. A 2-year-old male weighing 12 kg who ingested up to 4 mg of guanfacine developed lethargy. Gastric lavage (followed by activated charcoal and sorbitol slurry via NG tube) removed some tablet fragments within 2 hours after ingestion, and vital signs were normal. During 24-hour observation in ICU, systolic pressure was 58 and heart rate 70 at 16 hours post-ingestion. No intervention was required, and child was discharged fully recovered the next day. Treatment of Overdosage Gastric lavage and supportive therapy as appropriate. Guanfacine is not dialyzable in clinically significant amounts (2.4%). DOSAGE & ADMINISTRATION The recommended initial dose of guanfacine tablets, USP when given alone or in combination with another antihypertensive drug is 1 mg daily given at bedtime to minimize somnolence. If after 3 to 4 weeks of therapy 1 mg does not give a satisfactory result, a dose of 2 mg may be given, although most of the effect of guanfacine is seen at 1 mg (see CLINICAL PHARMACOLOGY ). Higher daily doses have been used, but adverse reactions increase significantly with doses above 3 mg/day. The frequency of rebound hypertension is low, but it can occur. When rebound occurs, it does so after 2 to 4 days, which is delayed compared with clonidine hydrochloride. This is consistent with the longer half-life of guanfacine. In most cases, after abrupt withdrawal of guanfacine, blood pressure returns to pretreatment levels slowly (within 2 to 4 days) without ill effects. HOW SUPPLIED Guanfacine tablets, USP are available in 2 tablet strengths of guanfacine (as the hydrochloride salt) as follows: 1 mg: white, oval, flat-faced, beveled-edge tablet with “AN” on one side and “711” on the other side. NDC 50268-373-15 (10 tablets per card, 5 cards per carton). 2 mg: white, oval, flat-faced, beveled-edge tablet with “AN” on one side and “713” on the other side. NDC 50268-374-15 (10 tablets per card, 5 cards per carton). Dispensed in Unit Dose Package. For Institutional Use Only. Store at 20º to 25 ºC (68 ºF to 77 ºF) [see USP Controlled Room Temperature]. Manufactured for: AvKARE, Inc. Pulaski, TN 38478
PACKAGE LABEL.PRINCIPAL DISPLAY PANEL
Marketing Information
Marketing Category Application Number or Monograph Citation Marketing Start Date Marketing End Date ANDA ANDA075109 06/07/
GUANFACINE HYDROCHLORIDE
guanfacine tablet Product Information Product Type HUMAN PRESCRIPTION DRUG Item Code (Source) NDC:50268-373(NDC:65162-
Route of Administration ORAL Active Ingredient/Active Moiety Ingredient Name Basis of Strength Strength GUANFACINE HYDROCHLORIDE (UNII: PML56A160O) (GUANFACINE - UNII:30OMY4G3MK) GUANFACINE^ 1 mg Inactive Ingredients Ingredient Name Strength CELLULOSE, MICROCRYSTALLINE (UNII: OP1R32D61U) STARCH, CORN (UNII: O8232NY3SJ) STEARIC ACID (UNII: 4ELV7Z 65AP) Product Characteristics Color white^ Score no s core Shape OVAL^ Size 11mm Flavor Imprint Code AN; **Contains Packaging
Item Code Package Description Marketing Start
Date Marketing End Date 1** NDC:50268-373- 15 50 in 1 BOX, UNIT-DOSE 09/27/2018 09/30/ 1 NDC:50268-373- 11 1 Product^ in 1 BLISTER PACK; Type 0: Not a Combination
Marketing Information
Marketing Application Number or Monograph Marketing Start Marketing End
AvPAK Category Citation Date Date ANDA ANDA075109 09/27/2018 09/30/
Labeler - AvPAK (832926666)
Revised: 1/
