Guanfacine


Actavis Pharma, Inc.
Human Prescription Drug
NDC 0591-0444
Guanfacine is a drug for further processing labeled by 'Actavis Pharma, Inc.'. National Drug Code (NDC) number for Guanfacine is 0591-0444. This drug is available in dosage form of Tablet. The names of the active, medicinal ingredients in Guanfacine drug includes Guanfacine Hydrochloride - 1 mg/1 . The currest status of Guanfacine drug is Active.

Drug Information:

Drug NDC: 0591-0444
The labeler code and product code segments of the National Drug Code number, separated by a hyphen. Asterisks are no longer used or included within the product code segment to indicate certain configurations of the NDC.
Proprietary Name: Guanfacine
Also known as the trade name. It is the name of the product chosen by the labeler.
Product Type: Human Prescription Drug
Indicates the type of product, such as Human Prescription Drug or Human OTC Drug. This data element corresponds to the “Document Type” of the SPL submission for the listing.
Non Proprietary Name: Guanfacine
Also known as the generic name, this is usually the active ingredient(s) of the product.
Labeler Name: Actavis Pharma, Inc.
Name of Company corresponding to the labeler code segment of the ProductNDC.
Dosage Form: Tablet
The translation of the DosageForm Code submitted by the firm. There is no standard, but values may include terms like `tablet` or `solution for injection`.The complete list of codes and translations can be found www.fda.gov/edrls under Structured Product Labeling Resources.
Status: Active
FDA does not review and approve unfinished products. Therefore, all products in this file are considered unapproved.
Substance Name:GUANFACINE HYDROCHLORIDE - 1 mg/1
This is the active ingredient list. Each ingredient name is the preferred term of the UNII code submitted.
Route Details:ORAL
The translation of the Route Code submitted by the firm, indicating route of administration. The complete list of codes and translations can be found at www.fda.gov/edrls under Structured Product Labeling Resources.

Marketing Information:

An openfda section: An annotation with additional product identifiers, such as NUII and UPC, of the drug product, if available.
Marketing Category: ANDA
Product types are broken down into several potential Marketing Categories, such as New Drug Application (NDA), Abbreviated New Drug Application (ANDA), BLA, OTC Monograph, or Unapproved Drug. One and only one Marketing Category may be chosen for a product, not all marketing categories are available to all product types. Currently, only final marketed product categories are included. The complete list of codes and translations can be found at www.fda.gov/edrls under Structured Product Labeling Resources.
Marketing Start Date: 17 Oct, 1995
This is the date that the labeler indicates was the start of its marketing of the drug product.
Marketing End Date: 26 Dec, 2024
This is the date the product will no longer be available on the market. If a product is no longer being manufactured, in most cases, the FDA recommends firms use the expiration date of the last lot produced as the EndMarketingDate, to reflect the potential for drug product to remain available after manufacturing has ceased. Products that are the subject of ongoing manufacturing will not ordinarily have any EndMarketingDate. Products with a value in the EndMarketingDate will be removed from the NDC Directory when the EndMarketingDate is reached.
Application Number: ANDA074145
This corresponds to the NDA, ANDA, or BLA number reported by the labeler for products which have the corresponding Marketing Category designated. If the designated Marketing Category is OTC Monograph Final or OTC Monograph Not Final, then the Application number will be the CFR citation corresponding to the appropriate Monograph (e.g. “part 341”). For unapproved drugs, this field will be null.
Listing Expiration Date: 31 Dec, 2023
This is the date when the listing record will expire if not updated or certified by the firm.

OpenFDA Information:

An openfda section: An annotation with additional product identifiers, such as NUII and UPC, of the drug product, if available.
Manufacturer Name:Actavis Pharma, Inc.
Name of manufacturer or company that makes this drug product, corresponding to the labeler code segment of the NDC.
RxCUI:197745
197746
The RxNorm Concept Unique Identifier. RxCUI is a unique number that describes a semantic concept about the drug product, including its ingredients, strength, and dose forms.
Original Packager:Yes
Whether or not the drug has been repackaged for distribution.
UPC:0305910444013
0305910453015
UPC stands for Universal Product Code.
UNII:PML56A160O
Unique Ingredient Identifier, which is a non-proprietary, free, unique, unambiguous, non-semantic, alphanumeric identifier based on a substance’s molecular structure and/or descriptive information.
Pharmacologic Class:Adrenergic alpha2-Agonists [MoA]
Central alpha-2 Adrenergic Agonist [EPC]
These are the reported pharmacological class categories corresponding to the SubstanceNames listed above.

Packaging Information:

Package NDCDescriptionMarketing Start DateMarketing End DateSample Available
0591-0444-01100 TABLET in 1 BOTTLE, PLASTIC (0591-0444-01)17 Oct, 1995N/ANo
Package NDC number, known as the NDC, identifies the labeler, product, and trade package size. The first segment, the labeler code, is assigned by the FDA. Description tells the size and type of packaging in sentence form. Multilevel packages will have the descriptions concatenated together.

Product Elements:

Guanfacine guanfacine guanfacine hydrochloride guanfacine anhydrous lactose fd&c red no. 40 cellulose, microcrystalline povidone stearic acid watson;444 guanfacine guanfacine guanfacine hydrochloride guanfacine anhydrous lactose d&c yellow no. 10 aluminum lake fd&c red no. 40 povidone stearic acid cellulose, microcrystalline peach watson;453

Drug Interactions:

Drug interactions: the potential for increased sedation when guanfacine is given with other cns-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).

Indications and Usage:

Indications and usage guanfacine tablets, usp are indicated in the management of hypertension. guanfacine tablets, usp may be given alone or in combination with other antihypertensive agents, especially thiazide-type diuretics.

General Precautions:

General: like other antihypertensive agents, guanfacine should be used with caution in patients with severe coronary insufficiency, recent myocardial infarction, cerebrovascular disease or chronic renal or hepatic failure.

Dosage and Administration:

Dosage and administration the recommended initial dose of guanfacine hydrochloride 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 2-4 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 2-4 days) without ill effects.

Contraindications:

Contraindications guanfacine tablets are contraindicated in patients with known hypersensitivity to guanfacine hydrochloride.

Adverse Reactions:

Adverse reactions adverse reactions noted with guanfacine are similar to those of other drugs of the central ? 2 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 placebo 0.5 mg 1 mg 2 mg 3 mg reaction n=59 n=60 n=61 n=60 n=59 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% 13% 7% 5% 3% impotence 0% 0% 0% 7% 3% co
nstipation 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 0% 2% 5% 13% 32% 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: placebo 0.5 mg 1 mg 2 mg 3 mg adverse reaction n = 73 n = 72 n = 72 n = 72 n = 72 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 (1%) 1 (0%) 0 (0%) 1 (1%) 3 (4%) constipation 0 (0%) 0 (0%) 0 (0%) 1 (1%) 1 (1%) fatigue 3 (3%) 2 (3%) 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 6.9% 4.2% 3.2% 6.9% 8.3% 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: guanfacine clonidine adverse reactions (n=279) (n=278) dry mouth 30% 37% somnolence 21% 35% dizziness 11% 8% constipation 10% 5% fatigue 9% 8% headache 4% 4% insomnia 4% 3% adverse reactions occurring in 3% or less of patients in the three controlled trials of guanfacine with a diuretic were: 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 diuretic plus beta blocker (6%), or with diuretic plus vasodilator (2%). the mean daily dose of guanfacine reached was 4.7 mg. adverse reaction incidence of adverse reactions at any time during the study incidence of adverse reactions at end of one year n=580 n=580 dry mouth 60% 15% drowsiness 33% 6% dizziness 15% 1% constipation 14% 3% weakness 5% 1% headache 4% 0.2% insomnia 5% 0% 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 guanfacine hydrochloride 1 mg/day given at bedtime for 28 days. guanfacine 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 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 musculoskeletal 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.

Adverse Reactions Table:

Adverse Placebo 0.5 mg 1 mg 2 mg 3 mg
Reaction n=59 n=60 n=61 n=60 n=59
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% 13% 7% 5% 3%
Impotence 0% 0% 0% 7% 3%
Constipation 0% 2% 0% 5% 15%
Fatigue 2% 2% 5% 8% 10%

Placebo 0.5 mg 1 mg 2 mg 3 mg
Percent dropouts 0% 2% 5% 13% 32%

Placebo 0.5 mg 1 mg 2 mg 3 mg
Adverse Reaction n = 73 n = 72 n = 72 n = 72 n = 72
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 (1%) 1 (0%) 0 (0%) 1 (1%) 3 (4%)
Constipation 0 (0%) 0 (0%) 0 (0%) 1 (1%) 1 (1%)
Fatigue 3 (3%) 2 (3%) 2 (3%) 5 (6%) 3 (4%)

Dose: Placebo 0.5 mg 1 mg 2 mg 3 mg
Percent dropouts 6.9% 4.2% 3.2% 6.9% 8.3%

Guanfacine Clonidine
Adverse Reactions (n=279) (n=278)
Dry Mouth 30% 37%
Somnolence 21% 35%
Dizziness 11% 8%
Constipation 10% 5%
Fatigue 9% 8%
Headache 4% 4%
Insomnia 4% 3%

Adverse Reaction Incidence of adverse reactions at any time during the study Incidence of adverse reactions at end of one year
n=580 n=580
Dry Mouth 60% 15%
Drowsiness 33% 6%
Dizziness 15% 1%
Constipation 14% 3%
Weakness 5% 1%
Headache 4% 0.2%
Insomnia 5% 0%

Drug Interactions:

Drug interactions: the potential for increased sedation when guanfacine is given with other cns-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).

Pediatric Use:

Pediatric use: safety and effectiveness in children under 12 years of age have not been demonstrated. therefore, the use of guanfacine in this age group is not recommended. there have been spontaneous postmarketing reports of mania and aggressive behavioral changes in pediatric patients with attention-deficit hyperactivity disorder (adhd) receiving guanfacine. the reported cases were from a single center. all patients had medical or family risk factors for bipolar disorder. all patients recovered upon discontinuation of guanfacine hcl. hallucinations have been reported in pediatric patients receiving guanfacine for treatment of attention-deficit hyperactivity disorder.

Geriatric Use:

Geriatric use: clinical studies of guanfacine did not include sufficient numbers of subjects aged 65 and over to determine whether they responded differently from younger subjects. other reported clinical experience has not identified differences in responses between the elderly and younger patients. 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 (see clinical pharmacology, pharmacokinetics ).

Overdosage:

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 30-40 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%).

Description:

Description guanfacine hydrochloride is a centrally acting antihypertensive with ? 2 -adrenoceptor agonist properties in tablet form for oral administration. the chemical name of guanfacine hydrochloride is n -amidino-2-(2,6-dichlorophenyl) acetamide monohydrochloride and its molecular weight is 282.55. its structural formula is: guanfacine hydrochloride 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 equivalent to 1 mg or 2 mg guanfacine. the tablets contain the following inactive ingredients: 1 mg - anhydrous lactose, fd&c red 40 aluminum lake, microcrystalline cellulose, povidone, stearic acid. 2 mg - anhydrous lactose, d&c yellow 10 aluminum lake, fd&c red 40 aluminum lake, microcrystalline cellulose, povidone, stearic acid. guanfacine hydrochloride chemical structure

Clinical Pharmacology:

Clinical pharmacology guanfacine hydrochloride is an orally active antihypertensive agent whose principal mechanism of action appears to be stimulation of central ? 2 -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 mean change s/d* seated n= (range) placebo 0.5 mg 1 mg 2 mg 3 mg 5 mg *s/d = systolic/diastolic blood pressure white patients 11-30 -1/-5 -6/-8 -8/-9 -12/-11 -15/-12 -18/-16 black patients 8-28 -3/-5 0/-2 -3/-5 -7/-7 -8/-9 -19/-15 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 = systolic/diastolic blood pressure s/d* seated -5/-7 -5/-6 -14/-13 -12/-13 -16/-13 s/d* standing -3/-5 -5/-4 -11/-9 -9/-10 -15/-12 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 were infrequent upon discontinuation of either drug. abrupt withdrawal of clonidine produced a rapid return of diastolic and especially, systolic blood pressure to approximately pretreatment levels, with occasional values significantly greater than baseline, whereas guanfacine withdrawal produced a more gradual increase to pretreatment levels, but also with occasional values significantly greater than baseline. pharmacodynamics: hemodynamic studies in man showed that the decrease in blood pressure observed after single-dose or long-term oral treatment with guanfacine was accompanied by a significant decrease in peripheral resistance and a slight reduction in heart rate (5 beats/min). cardiac output under conditions of rest or exercise was not altered by guanfacine. guanfacine lowered elevated plasma renin activity and plasma catecholamine levels in hypertensive patients, but this does not correlate with individual blood-pressure responses. growth hormone secretion was stimulated with single oral doses of 2 and 4 mg of guanfacine. long-term use of guanfacine had no effect on growth hormone levels. guanfacine had no effect on plasma aldosterone. a slight but insignificant decrease in plasma volume occurred after one month of guanfacine therapy. there were no changes in mean body weight or electrolytes. pharmacokinetics: relative to an intravenous dose of 3 mg, the absolute oral bioavailability of guanfacine is about 80%. peak plasma concentrations occur from 1 to 4 hours with an average of 2.6 hours after single oral doses or at steady state. the area under the concentration-time curve (auc) increases linearly with the dose. in individuals with normal renal function, the average elimination half-life is approximately 17 hr (range 10-30 hr). younger patients tend to have shorter elimination half-lives (13-14 hr) while older patients tend to have half-lives at the upper end of the range. steady state blood levels were attained within 4 days in most subjects. in individuals with normal renal function, guanfacine and its metabolites are excreted primarily in the urine. approximately 50% (40-75%) of the dose is eliminated in the urine as unchanged drug; the remainder is eliminated mostly as conjugates of metabolites produced by oxidative metabolism of the aromatic ring. the guanfacine-to-creatinine clearance ratio is greater than 1, which would suggest that tubular secretion of drug occurs. the drug is approximately 70% bound to plasma proteins, independent of drug concentration. the whole body volume of distribution is high (a mean of 6.3 l/kg), which suggests a high distribution of drug to the tissues. the clearance of guanfacine in patients with varying degrees of renal insufficiency is reduced, but plasma levels of drug are only slightly increased compared to patients with normal renal function. when prescribing for patients with renal impairment, the low end of the dosing range should be used. patients on dialysis also can be given usual doses of guanfacine hydrochloride as the drug is poorly dialyzed.

Pharmacodynamics:

Pharmacodynamics: hemodynamic studies in man showed that the decrease in blood pressure observed after single-dose or long-term oral treatment with guanfacine was accompanied by a significant decrease in peripheral resistance and a slight reduction in heart rate (5 beats/min). cardiac output under conditions of rest or exercise was not altered by guanfacine. guanfacine lowered elevated plasma renin activity and plasma catecholamine levels in hypertensive patients, but this does not correlate with individual blood-pressure responses. growth hormone secretion was stimulated with single oral doses of 2 and 4 mg of guanfacine. long-term use of guanfacine had no effect on growth hormone levels. guanfacine had no effect on plasma aldosterone. a slight but insignificant decrease in plasma volume occurred after one month of guanfacine therapy. there were no changes in mean body weight or electrolytes.

Pharmacokinetics:

Pharmacokinetics: relative to an intravenous dose of 3 mg, the absolute oral bioavailability of guanfacine is about 80%. peak plasma concentrations occur from 1 to 4 hours with an average of 2.6 hours after single oral doses or at steady state. the area under the concentration-time curve (auc) increases linearly with the dose. in individuals with normal renal function, the average elimination half-life is approximately 17 hr (range 10-30 hr). younger patients tend to have shorter elimination half-lives (13-14 hr) while older patients tend to have half-lives at the upper end of the range. steady state blood levels were attained within 4 days in most subjects. in individuals with normal renal function, guanfacine and its metabolites are excreted primarily in the urine. approximately 50% (40-75%) of the dose is eliminated in the urine as unchanged drug; the remainder is eliminated mostly as conjugates of metabolites produced by oxidative metabolism of the aromatic ring. the guanfacine-to-
creatinine clearance ratio is greater than 1, which would suggest that tubular secretion of drug occurs. the drug is approximately 70% bound to plasma proteins, independent of drug concentration. the whole body volume of distribution is high (a mean of 6.3 l/kg), which suggests a high distribution of drug to the tissues. the clearance of guanfacine in patients with varying degrees of renal insufficiency is reduced, but plasma levels of drug are only slightly increased compared to patients with normal renal function. when prescribing for patients with renal impairment, the low end of the dosing range should be used. patients on dialysis also can be given usual doses of guanfacine hydrochloride as the drug is poorly dialyzed.

Carcinogenesis and Mutagenesis and Impairment of Fertility:

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.

How Supplied:

How supplied guanfacine tablets, usp are available in the following dosing strengths (expressed in equivalent amounts of guanfacine): guanfacine tablets, usp 1 mg, are pink, round tablets, debossed with watson 444 and are available in bottles of 100. guanfacine tablets, usp 2 mg, are peach, round tablets, debossed with watson 453 and are available in bottles of 100. bottles of 100 tablets are supplied with child-resistant closures. store at 20° to 25°c (68° to 77°f) [see usp controlled room temperature]. dispense in a tight, light-resistant container. manufactured by: watson pharma private limited verna, salcette goa 403 722 india distributed by: actavis pharma, inc. parsippany, nj 07054 usa revised: july 2014 198950-1

Information for Patients:

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.

Package Label Principal Display Panel:

Principal display panel - 1 mg ndc 0591-0444-01 guanfacine tablets, usp 1 mg actavis 100 tablets rx only 1 mg

Principal display panel - 2mg ndc 0591-0453-01 guanfacine tablets, usp 2 mg actavis 100 tablets rx only 2 mg


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