Guanfacine Er

FDA Drug Information • Also known as: Guanfacine Er

Brand Names: Guanfacine Er
Route: ORAL
Dosage Form: TABLET, EXTENDED RELEASE
Product Type: HUMAN PRESCRIPTION DRUG

Description

Guanfacine extended-release tablets, USP are a once-daily, extended-release formulation of guanfacine hydrochloride 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 C9H9Cl2N3O·HCl corresponding to a molecular weight of 282.55 g/mol. The chemical structure is: [spd503-chemical-stucture] Guanfacine hydrochloride, USP is a white to off-white 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 anhydrous lactose, colloidal silicon dioxide, fumaric acid, hypromellose and magnesium stearate. In addition, the 3-mg and 4-mg tablets also contain FD&C Blue #2 and ferric oxide yellow. Dissolution test pending.

What Is Guanfacine Er Used For?

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)].

Dosage and Administration

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 tablets 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 - 0.12 mg/kg/day) 25-33.9 kg 2-3 mg/day 34-41.4 kg 2-4 mg/day 41.5-49.4 kg 3-5 mg/day 49.5-58.4 kg 3-6 mg/day 58.5-91 kg 4-7 mg/day >91 kg 5-7 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 tablets have 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 to 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...

Side Effects (Adverse Reactions)

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 extended-release tablets 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 Extended-Release Tablets (mg) Adverse Reaction Term Placebo (N=149) 1mg* (N=61) 2mg (N=150) 3mg (N=151) 4mg (N=151) All Doses of Guanfacine Extended-Release Tablets (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 Extended-Release Tablets and >rate than in placebo) in Fixed Dose Studies 1 and 2 Guanfacine Extended-Release Tablets (mg) Adverse Reaction Term Placebo (N=149) 1mg* (N=61) 2mg (N=150) 3mg (N=151) 4mg (N=151) All Doses of Guanfacine Extended-Release Tablets (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 Extended-Release Tablets and >rate than in placebo) in Fixed Dose Studies 1 and 2 Guanfacine Extended-Release Tablets (mg) Adverse Reaction Term Placebo (N=149) 1mg* (N=61) 2mg (N=150) 3mg (N=151) 4mg (N=151) All Doses of Guanfacine Extended-Release Tablets (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 extended-release tablets 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,...

Contraindications

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.

Overdosage

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.

How Supplied

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. They are supplied as follows: Bottles of 30s (NDC 72189-469-30) 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. They are supplied as follows: Bottles of 100s (NDC 60505-3928-1) Guanfacine extended-release tablets, USP 3 mg are green, round, biconvex tablets, engraved “APO” on one side, “GU3” on the other side. They are supplied as follows: Bottles of 100s (NDC 60505-3929-1) Guanfacine extended-release tablets, USP 4 mg are green, oval shaped, biconvex tablets, engraved “APO” on one side, “GUA 4” on the other side. They are supplied as follows: Bottles of 100s (NDC 60505-3930-1)

About This Information

This drug information is sourced from FDA-approved labeling via the openFDA database. It is intended for educational and reference purposes only. This is not medical advice. Always consult your healthcare provider before making decisions about medication. Drug information may be updated by the FDA; check with your pharmacist for the most current information.

What are side effects?

Side effects are unwanted reactions that can occur when taking a medication. They range from mild (headache, nausea) to severe (allergic reactions, organ damage). Not everyone experiences side effects, and severity varies. Report any concerning side effects to your doctor.

What are drug interactions?

Drug interactions occur when a medication is affected by another drug, food, or supplement. Interactions can make medications less effective or cause dangerous side effects. Always tell your doctor about all medications and supplements you take.