Guanfacine ER

Guanfacine extended-release tablets are indicated for the treatment of Attention Deficit Hyperactivity Disorder (ADHD) as monotherapy and as adjunctive therapy to stimulant medications [see Clinical Studies (14)].

2.1 General Instruction for Use Swallow tablets whole. Do not crush, chew, or break tablets because this will increase the rate of guanfacine release. Do not administer with high fat meals, due to increased exposure. 2.2 Dose Selection Take guanfacine extended-release tablets orally once daily, either in the morning or evening, at approximately the same time each day. Begin at a dose of 1 mg/day, and adjust in increments of no more than 1 mg/week. In monotherapy clinical trials, there was dose-and exposure-related clinical improvement as well as risks for several clinically significant adverse reactions (hypotension, bradycardia, sedative events). To balance the exposure-related potential benefits and risks, the recommended target dose range depending on clinical response and tolerability for guanfacine extended-release tablet is 0.05 to 0.12 mg/kg/day (total daily dose between 1 to 7 mg) (See Table 1). Table 1: Recommended Target Dose Range for Therapy with Guanfacine Extended-Release Tablets Weight Target dose range (0.05 to 0.12 mg/kg/day) 25 to 33.9 kg 2 to 3 mg/day 34 to 41.4 kg 2 to 4 mg/day 41.5 to 49.4 kg 3 to 5 mg/day 49.5 to 58.4 kg 3 to 6 mg/day 58.5 to 91 kg 4 to 7 mg/day >91 kg 5 to 7 mg/day Doses above 4 mg/day have not been evaluated in children (ages 6 to12 years) and doses above 7 mg/day have not been evaluated in adolescents (ages 13 to 17 years) In the adjunctive trial which evaluated guanfacine extended-release tablets treatment with psychostimulants, the majority of patients reached optimal doses in the 0.05 to 0.12 mg/kg/day range. Doses above 4 mg/day have not been studied in adjunctive trials. 2.3 Switching from Immediate-Release Guanfacine to Guanfacine Extended-Release Tablets If switching from immediate-release guanfacine, discontinue that treatment, and titrate with guanfacine extended-release tablets following above recommended schedule. Do not substitute for immediate-release guanfacine tablets on a milligram-per-milligram basis, because of differing pharmacokinetic profiles. Guanfacine extended-release tablet has significantly reduced Cmax (60% lower), bioavailability (43% lower), and a delayed Tmax (3 hours later) compared to those of the same dose of immediate-release guanfacine [see Clinical Pharmacology (12.3)]. 2.4 Maintenance Treatment Pharmacological treatment of ADHD may be needed for extended periods. Healthcare providers should periodically re-evaluate the long-term use of guanfacine extended-release tablets, and adjust weight-based dosage as needed. The majority of children and adolescents reach optimal doses in the 0.05-0.12 mg/kg/day range. Doses above 4 mg/day have not been evaluated in children (ages 6 to 12 years) and above 7 mg/day have not been evaluated in adolescents (ages 13 to 17 years) [see Clinical Studies (14)]. 2.5 Discontinuation of Treatment Following discontinuation of guanfacine extended-release tablets, patients may experience increases in blood pressure and heart rate [see Warnings and Precautions (5.4) and Adverse Reactions (6)]. Patients/caregivers should be instructed not to discontinue guanfacine extended-release tablets without consulting their health care provider. Monitor blood pressure and pulse when reducing the dose or discontinuing the drug. Taper the daily dose in decrements of no more than 1 mg every 3 to 7 days to minimize the risk of rebound hypertension. 2.6 Missed Doses When reinitiating patients to the previous maintenance dose after two or more missed consecutive doses, consider titration based on patient tolerability. 2.7 Dosage Adjustment with Concomitant Use of Strong and Moderate CYP3A4 Inhibitors or Inducers Dosage adjustments for guanfacine extended-release tablets are recommended with concomitant use of strong and moderate CYP3A4 inhibitors (e.g., ketoconazole), or CYP3A4 inducers (e.g., carbamazepine) (Table 2) [see Drug Interactions (7)]. Table 2: Guanfacine Extended-Release Tablets Dosage Adjustments for Patients Taking Concomitant CYP3 …

Guanfacine extended-release tablets, USP 1 mg are white to off-white, round, biconvex tablets, engraved "APO" on one side, "GU1" on the other side. Guanfacine extended-release tablets, USP 2 mg are white to off-white, oval shaped, biconvex tablets, engraved "APO" on one side, "GUA 2" on the other side. Guanfacine extended-release tablets, USP 3 mg are green, round, biconvex tablets, engraved "APO" on one side, "GU3" on the other side. Guanfacine extended-release tablets, USP 4 mg are green, oval shaped, biconvex tablets, engraved "APO" on one side, "GUA 4" on the other side.

Guanfacine extended-release tablets are contraindicated in patients with a history of a hypersensitivity reaction to guanfacine extended-release tablets or its inactive ingredients, or other products containing guanfacine. Rash and pruritus have been reported.

The following serious adverse reactions are described elsewhere in the labeling: Hypotension, bradycardia, and syncope [see Warnings and Precautions (5.1)] Sedation and somnolence [see Warnings and Precautions (5.2)] Cardiac conduction abnormalities [see Warnings and Precautions (5.3)] Rebound Hypertension [see Warnings and Precautions (5.4)] 6.1 Clinical Trials Experience Because clinical trials are conducted under widely varying conditions, adverse reaction rates observed in the clinical trials of a drug cannot be directly compared to rates in the clinical trials of another drug and may not reflect the rates observed in practice. The data described below reflect clinical trial exposure to guanfacine in 2,825 patients. This includes 2,330 patients from completed studies in children and adolescents, ages 6 to 17 years and 495 patients in completed studies in adult healthy volunteers. The mean duration of exposure of 446 patients that previously participated in two 2-year, open-label long-term studies was approximately 10 months. Fixed Dose Trials Table 3: Percentage of Patients Experiencing Most Common (≥5% and at least twice the rate for placebo) Adverse Reactions in Fixed Dose Studies 1 and 2 Guanfacine (mg) Adverse Reaction Term Placebo (N=149) 1 mg* (N=61) 2 mg (N=150) 3 mg (N=151) 4 mg (N=151) All Doses of Guanfacine (N=513) Somnolencea 11% 28% 30% 38% 51% 38% Fatigue 3% 10% 13% 17% 15% 14% Hypotensionb 3% 8% 5% 7% 8% 7% Dizziness 4% 5% 3% 7% 10% 6% Lethargy 3% 2% 3% 8% 7% 6% Nausea 2% 7% 5% 5% 6% 6% Dry mouth 1% 0% 1% 6% 7% 4% * The lowest dose of 1 mg used in Study 2 was not randomized to patients weighing more than 50 kg. a: The somnolence term includes somnolence, sedation, and hypersomnia. b: The hypotension term includes hypotension, diastolic hypotension, orthostatic hypotension, blood pressure decreased, blood pressure diastolic decreased, blood pressure systolic decreased). Table 4: Adverse Reactions Leading to Discontinuation (≥2% for all doses of Guanfacine and >rate than in placebo) in Fixed Dose Studies 1 and 2 Guanfacine (mg) Adverse Reaction Term Placebo (N=149) 1 mg* (N=61) 2 mg (N=150) 3 mg (N=151) 4 mg (N=151) All Doses of Guanfacine (N=513) n (%) n (%) n (%) n (%) n (%) n (%) Total patients 4 (3%) 2 (3%) 10 (7%) 15 (10%) 27 (18%) 54 (11%) Somnolencea 1 (1%) 2 (3%) 5 (3%) 6 (4%) 17 (11%) 30 (6%) Fatigue 0 (0%) 0 (0%) 2 (1%) 2 (1%) 4 (3%) 8 (2%) Adverse reactions leading to discontinuation in ≥2% in any dose group but did not meet this criteria in all doses combined: hypotension (hypotension, diastolic hypotension, orthostatic hypotension, blood pressure decreased, blood pressure diastolic decreased, blood pressure systolic decreased), headache, and dizziness. * The lowest dose of 1 mg used in Study 2 was not randomized to patients weighing more than 50 kg. a: The somnolence term includes somnolence, sedation, and hypersomnia. Table 5: Other Common Adverse Reactions (≥2% for all doses of Guanfacine and >rate than in placebo) in Fixed Dose Studies 1 and 2 Guanfacine (mg) Adverse Reaction Term Placebo (N=149) 1 mg* (N=61) 2 mg (N=150) 3 mg (N=151) 4 mg (N=151) All Doses of Guanfacine (N=513) Headache 19% 26% 25% 16% 28% 23% Abdominal Paina 9% 10% 7% 11% 15% 11% Decreased Appetite 4% 5% 4% 9% 6% 6% Irritability 4% 5% 8% 3% 7% 6% Constipation 1% 2% 2% 3% 4% 3% Nightmareb 0% 0% 0% 3% 4% 2% Enuresisc 1% 0% 1% 3% 2% 2% Affect Labilityd 1% 2% 1% 3% 1% 2% Adverse reactions ≥2% for all doses of guanfacine and >rate in placebo in any dose group but did not meet this criteria in all doses combined: insomnia (insomnia, initial insomnia, middle insomnia, terminal insomnia, sleep disorder), vomiting, diarrhea, abdominal/stomach discomfort (abdominal discomfort, epigastric discomfort, stomach discomfort), rash (rash, rash generalized, rash papular), dyspepsia, increased weight, bradycardia (bradycardia, sinus bradycardia), asthma (asthma, bronchospasm, wheezing), agitation, anxiety (anxiety, nervousness), sinus arrhythmi …

Table 14 contains clinically important drug interactions with guanfacine [see Clinical Pharmacology (12.3)]. Table 14: Clinically Important Drug Interactions: Effect of other Drugs on Guanfacine Concomitant Drug Name or Drug Class Clinical Rationale and Magnitude of Drug Interaction Clinical Recommendation Strong and moderate CYP3A4 inhibitors, e.g., ketoconazole, fluconazole Guanfacine is primarily metabolized by CYP3A4 and its plasma concentrations can be significantly affected resulting in an increase in exposure Consider dose reduction [see Dosage and administration (2.7)] Strong and moderate CYP3A4 inducers, e.g., rifampin, efavirenz Guanfacine is primarily metabolized by CYP3A4 and its plasma concentrations can be significantly affected resulting in a decrease in exposure Consider dose increase [see Dosage and administration (2.7)]

8.1 Pregnancy Pregnancy Exposure Registry There is a pregnancy exposure registry that monitors pregnancy outcomes in women exposed to ADHD medications, including guanfacine extended-release tablets, during pregnancy. Healthcare providers are encouraged to register patients by calling the National Pregnancy Registry for ADHD Medications at 1-866-961-2388. Risk Summary Available data with guanfacine over decades of use in pregnant women have not identified a drug-associated risk of major birth defects, miscarriage or adverse maternal or fetal outcomes. However, use of guanfacine in pregnant women over this time has been infrequent. In animal reproduction studies, rabbits and rats exposed to 3 and 4 times the maximum recommended human dose (MRHD), respectively, showed no adverse outcomes. However, higher doses were associated with reduced fetal survival and maternal toxicity (see Data). The estimated background risk of major birth defects and miscarriage for the indicated population is unknown. All pregnancies have a background risk of birth defect, loss, or other adverse outcomes. In the U.S. general population, the estimated risk of major birth defects and miscarriage in clinically recognized pregnancies is 2% to 4% and 15% to 20%, respectively. Data Animal Data Reproduction studies conducted in rats have shown that guanfacine crosses the placenta. However, administration of guanfacine to rabbits and rats during organogenesis at 3 (rabbit) and 4 (rat) times the MRHD of 0.12 mg/kg/day on a mg/m2 basis resulted in no evidence of harm to the fetus. Higher doses (13.5 times the MRHD in both rabbits and rats) were associated with reduced fetal survival and maternal toxicity. 8.2 Lactation Risk Summary There are no data on the presence of guanfacine in human milk or the effects on the breastfed infant. The effects on milk production are also unknown. Guanfacine is present in the milk of lactating rats (see Data). If a drug is present in animal milk, it is likely that the drug will be present in human milk. If an infant is exposed to guanfacine through breastmilk, monitor for symptoms of hypotension and bradycardia such as sedation, lethargy and poor feeding (see Clinical Considerations). The developmental and health benefits of breastfeeding should be considered along with the mother’s clinical need for guanfacine extended-release tablets and any potential adverse effects on the breastfed child from guanfacine extended-release tablets or from the underlying maternal condition. Clinical Considerations Monitor breastfeeding infants exposed to guanfacine through breastmilk for sedation, lethargy, and poor feeding. Data Guanfacine was excreted in breast milk of lactating rats at a concentration comparable to that observed in blood, but slightly less than the concentration in plasma when administered following a single oral dose of 5 mg/kg. The concentration of drug in animal milk does not necessarily predict the concentration of drug in human milk. 8.4 Pediatric Use Safety and efficacy of guanfacine extended-release tablets in pediatric patients less than 6 years of age have not been established. The efficacy of guanfacine extended-release tablets was studied for the treatment of ADHD in five controlled monotherapy clinical trials (up to 15 weeks in duration), one randomized withdrawal study and one controlled adjunctive trial with psychostimulants (8 weeks in duration) in children and adolescents ages 6 to 17 who met DSM-IV® criteria for ADHD [see ADVERSE REACTIONS (6) and CLINICAL STUDIES (14)]. Animal Data In studies in juvenile rats, guanfacine alone produced a slight delay in sexual maturation in males and females at 2 to 3 times the maximum recommended human dose (MRHD). Guanfacine in combination with methylphenidate produced a slight delay in sexual maturation and decreased growth as measured by a decrease in bone length in males at a dose of guanfacine comparable to the MRHD and a dose of methylphenidate approximately 4 times the …

Guanfacine is a once-daily, extended-release formulation of guanfacine hydrochloride, USP in a matrix tablet formulation for oral administration only. The chemical designation is N-amidino-2-(2,6-dichlorophenyl) acetamide monohydrochloride. The molecular formula is C9H9Cl2 N3O·HCl corresponding to a molecular weight of 282.55. The chemical structure is: [structure] Guanfacine hydrochloride, USP is a white to off-white crystalline powder, sparingly soluble in water (approximately 1 mg/mL) and alcohol and slightly soluble in acetone. The only organic solvent in which it has relatively high solubility is methanol (>30 mg/mL). Each tablet contains guanfacine hydrochloride, USP equivalent to 1 mg, 2 mg, 3 mg, or 4 mg of guanfacine base. The tablets also contain methacrylic acid and ethyl acrylate copolymer, hypromellose, glyceryl dibehenate, microcrystalline cellulose, lactose monohydrate, fumaric acid, talc, silicon dioxide and magnesium stearate. In addition, the 3 mg and 4 mg tablets also contain FD&C Blue #2 Aluminum Lake and iron oxide yellow. FDA approved dissolution test specifications differ from USP.

Symptoms Postmarketing reports of guanfacine overdosage indicate that hypotension, drowsiness, lethargy, and bradycardia have been observed following overdose. Initial hypertension may develop early and may be followed by hypotension. Similar symptoms have been described in voluntary reports to the American Association of Poison Control Center’s National Poison Data System. Miosis of the pupils may be noted on examination. No fatal overdoses of guanfacine have been reported in published literature. Treatment Consult a Certified Poison Control Center by calling 1-800-222-1222 for up-to-date guidance and advice. Management of guanfacine extended-release tablets overdose should include monitoring for and the treatment of initial hypertension, if that occurs, as well as hypotension, bradycardia, lethargy and respiratory depression. Children and adolescents who develop lethargy should be observed for the development of more serious toxicity including coma, bradycardia and hypotension for up to 24 hours, due to the possibility of delayed onset hypotension.

Guanfacine extended-release tablets, USP are supplied in 1 mg, 2 mg, 3 mg, and 4 mg strength as follows: Guanfacine extended-release tablets USP, 1 mg are white to off white colored, round shaped tablets, debossed with ‘L657’ on one side and plain on other side. Bottles of 30 tablets with child-resistant closure, NDC 72189-597-30 Bottles of 1000 tablets, NDC 62332-745-91 Guanfacine extended-release tablets USP, 2 mg are white to off white colored, caplet shaped tablets, debossed with ‘L658’ on one side and plain on other side. Bottles of 100 tablets with child-resistant closure, NDC 62332-746-31 Bottles of 1000 tablets, NDC 62332-746-91 Guanfacine extended-release tablets USP, 3 mg are light green to green colored, round shaped tablets, debossed with ‘L659’ on one side and plain on other side. Bottles of 100 tablets with child-resistant closure, NDC 62332-747-31 Bottles of 1000 tablets, NDC 62332-747-91 Guanfacine extended-release tablets USP, 4 mg are light green to green colored, caplet shaped tablets, debossed with ‘L660’ on one side and plain on other side. Bottles of 100 tablets with child-resistant closure, NDC 62332-748-31 Bottles of 1000 tablets, NDC 62332-748-91