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 0.05-0.12 mg/kg/day (total daily dose between 1-7 mg) (See Table 1).

In the adjunctive trial which evaluated guanfacine extended-release tablets treatment with psychostimulants, the majority of patients reached optimal doses in the 0.05-0.12 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 C max(60% lower), bioavailability (43% lower), and a delayed T max(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)] .

5.1 Hypotension, Bradycardia, and Syncope

Treatment with guanfacine extended-release tablets can cause dose-dependent decreases in blood pressure and heart rate. Decreases were less pronounced over time of treatment. Orthostatic hypotension and syncope have been reported  [see Adverse Reactions (6.1)] .

Measure heart rate and blood pressure prior to initiation of therapy, following dose increases, and periodically while on therapy. Titrate guanfacine extended-release tablets slowly in patients with a history of hypotension, and those with underlying conditions that may be worsened by hypotension and bradycardia; e.g., heart block, bradycardia, cardiovascular disease, vascular disease, cerebrovascular disease, or chronic renal failure. In patients who have a history of syncope or may have a condition that predisposes them to syncope, such as hypotension, orthostatic hypotension, bradycardia, or dehydration, advise patients to avoid becoming dehydrated or overheated. Monitor blood pressure and heart rate, and adjust dosages accordingly in patients treated concomitantly with antihypertensives or other drugs that can reduce blood pressure or heart rate or increase the risk of syncope.

5.2 Sedation and Somnolence

Somnolence and sedation were commonly reported adverse reactions in clinical studies [see Adverse Reactions (6.1)] . Before using guanfacine extended-release tablets with other centrally active depressants, consider the potential for additive sedative effects. Caution patients against operating heavy equipment or driving until they know how they respond to treatment with guanfacine extended-release tablets. Advise patients to avoid use with alcohol.

5.3 Cardiac Conduction Abnormalities

The sympatholytic action of guanfacine extended-release tablets may worsen sinus node dysfunction and atrioventricular (AV) block, especially in patients taking other sympatholytic drugs. Titrate guanfacine extended-release tablets slowly and monitor vital signs frequently in patients with cardiac conduction abnormalities or patients concomitantly treated with other sympatholytic drugs.

5.4 Rebound Hypertension

In post marketing experience, abrupt discontinuation of guanfacine extended-release tablets has resulted in clinically significant and persistent rebound hypertension above baseline levels and increases in heart rate. Hypertensive encephalopathy has also been reported in association with rebound hypertension with both guanfacine extended-release tablets and immediate release guanfacine  [see Adverse Reactions (6.2)] . In these cases, high-dosage guanfacine was discontinued; concomitant stimulant use was also reported, which may potentially increase hypertensive response upon abrupt discontinuation of guanfacine. Children commonly have gastrointestinal illnesses that lead to vomiting, and a resulting inability to take medications, so they may be especially at risk for rebound hypertension.

To minimize the risk of rebound hypertension upon discontinuation, the total daily dose of guanfacine extended-release tablets should be tapered in decrements of no more than 1 mg every 3 to 7 days  [see Dosage and Administration (2.5)] . Blood pressure and heart rate should be monitored when reducing the dose or discontinuing guanfacine extended-release tablets. If abrupt discontinuation occurs (especially with concomitant stimulant use), patients should be closely followed for rebound hypertension.

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.

6.2 Postmarketing Experience

The following adverse reactions have been identified during post-approval use of guanfacine. Because these reactions are reported voluntarily from a population of uncertain size, it is not always possible to reliably estimate their frequency or establish a causal relationship to drug exposure.

Less frequent, possibly guanfacine-related events observed in the post-marketing study and/or reported spontaneously, not included in section 6.1, include:

General:edema, malaise, tremor

Cardiovascular:palpitations, tachycardia, rebound hypertension, hypertensive encephalopathy

Central Nervous System:paresthesias, vertigo

Eye Disorders:blurred vision

Musculo-Skeletal System:arthralgia, leg cramps, leg pain, myalgia

Psychiatric:confusion, hallucinations

Reproductive System, Male:erectile dysfunction

Respiratory System:dyspnea

Skin and Appendages:alopecia, dermatitis, exfoliative dermatitis, pruritus, rash

Special Senses:alterations in taste

8.1 Pregnancy

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)].

8.5 Geriatric Use

The safety and efficacy of guanfacine extended-release tablets in geriatric patients have not been established.

8.6 Renal Impairment

It may be necessary to reduce the dosage in patients with significant impairment of renal function [see Clinical Pharmacology (12.3)].

8.7 Hepatic Impairment

It may be necessary to reduce the dosage in patients with significant impairment of hepatic function [see Clinical Pharmacology (12.3)].

9.1 Controlled Substance

Guanfacine extended-release tablets are not a controlled substance and have no known potential for abuse or dependence.

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.

12.1 Mechanism of Action

Guanfacine is a central alpha 2A-adrenergic receptor agonist. Guanfacine is not a central nervous system (CNS) stimulant. The mechanism of action of guanfacine in ADHD is not known.

12.2 Pharmacodynamics

Guanfacine is a selective central alpha 2A-adrenergic receptor agonist in that it has a 15 to 20 times higher affinity for this receptor subtype than for the alpha 2Bor alpha 2Csubtypes.

Guanfacine is a known antihypertensive agent. By stimulating central alpha 2A-adrenergic 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.

In a thorough QT study, the administration of two dose levels of immediate-release guanfacine (4 mg and 8 mg) produced concentrations approximately 2 to 4 times the concentrations observed with the maximum recommended dose of guanfacine extended-release tablets of 0.12 mg/kg. Guanfacine was not shown to prolong the QTc interval to any clinically relevant extent.

12.3 Pharmacokinetics

13.1 Carcinogenesis, Mutagenesis, Impairment of Fertility

Studies 1 and 2: Fixed-dose Guanfacine Extended-Release Tablets Monotherapy

Study 1 (301 study) was a double-blind, placebo-controlled, parallel-group, fixed-dose study, in which efficacy of once daily dosing with guanfacine extended-release tablets (2 mg, 3 mg and 4 mg) was evaluated for 5 weeks (n=345) in children and adolescents aged 6 to 17 years. Study 2 (304 study) was a double-blind, placebo-controlled, parallel-group, fixed-dose study, in which efficacy of once daily dosing with guanfacine extended-release tablets (1 mg, 2 mg, 3 mg and 4 mg) was evaluated for 6 weeks (n=324) in children and adolescents aged 6 to 17 years. In both studies, randomized patients in 2 mg, 3 mg and 4 mg dose groups were titrated to their target fixed dose, and continued on the same dose until a dose tapering phase started. The lowest dose of 1 mg used in Study 2 was not randomized to patients weighing more than 50 kg. Patients who weighed less than 25 kg were not included in either study.

Signs and symptoms of ADHD were evaluated on a once weekly basis using the clinician administered and scored ADHD Rating Scale (ADHD-RS-IV), which includes both hyperactive/impulsive and inattentive subscales. The primary efficacy outcome was the change from baseline to endpoint in ADHD-RS-IV total scores. Endpoint was defined as the last post-randomization treatment week for which a valid score was obtained prior to dose tapering (up to Week 5 in Study 1 and up to Week 6 in Study 2).

The mean reductions in ADHD-RS-IV total scores at endpoint were statistically significantly greater for guanfacine extended-release tablets compared to placebo for Studies 1 and 2. Placebo-adjusted changes from baseline were statistically significant for each of the 2 mg, 3 mg, and 4 mg guanfacine extended-release tablets randomized treatment groups in both studies, as well as the 1 mg guanfacine extended-release tablets treatment group that was included only in Study 2 (see Table 16).

Dose-responsive efficacy was evident, particularly when data were examined on a weight-adjusted (mg/kg) basis. When evaluated over the dose range of 0.01-0.17 mg/kg/day, clinically relevant improvements were observed beginning at doses in the range 0.05-0.08 mg/kg/day. Doses up to 0.12 mg/kg/day were shown to provide additional benefit.

In the monotherapy trials (Studies 1 and 2), subgroup analyses were performed to identify any differences in response based on gender or age (6 to 12 vs. 13 to 17). Analyses of the primary outcome did not suggest any differential responsiveness on the basis of gender. Analyses by age revealed a statistically significant treatment effect only in the 6 to 12 age subgroup. Due to the relatively small proportion of adolescent patients (ages 13 to 17) enrolled into these studies (approximately 25%), these data may not have been sufficient to demonstrate efficacy in the adolescent patients. In these studies, patients were randomized to a fixed dose of guanfacine extended-release tablets rather than optimized by body weight. Therefore, some adolescent patients were randomized to a dose that might have resulted in relatively lower plasma guanfacine concentrations compared to the younger patients. Over half (55%) of the adolescent patients received doses of 0.01-0.04 mg/kg. In studies in which systematic pharmacokinetic data were obtained, there was a strong inverse correlation between body weight and plasma guanfacine concentrations.

SD: standard deviation; SE: standard error; LS Mean: least-squares mean; CI: unadjusted confidence interval.
a Difference (drug minus placebo) in least-squares mean change from baseline.
*Doses statistically significantly superior to placebo.
^ The lowest dose of 1 mg used in Study 2 was not randomized to patients weighing more than 50 kg.

Study 3: Flexible-dose Guanfacine Extended-Release Tablets as Adjunctive Therapy to Psychostimulants

Study 3 (313 study) was a double-blind, randomized, placebo-controlled, dose-optimization study, in which efficacy of once daily optimized dosing (morning or evening) with guanfacine extended-release tablets (1 mg, 2 mg, 3 mg and 4 mg), when co-administered with psychostimulants, was evaluated for 8 weeks, in children and adolescents aged 6 to 17 years with a diagnosis of ADHD, with a sub-optimal response to stimulants (n=455). Patients were started at the 1 mg guanfacine extended-release tablets dose level and were titrated weekly over a 5-week dose-optimization period to an optimal guanfacine extended-release tablets dose not to exceed 4 mg/day based on tolerability and clinical response. The dose was then maintained for a 3-week dose maintenance period before entry to 1 week of dose tapering. Patients took guanfacine extended-release tablets either in the morning or the evening while maintaining their current dose of psychostimulant treatment given each morning. Allowable psychostimulants in the study were ADDERALL XR ®, VYVANSE ®, CONCERTA ®, FOCALIN XR ®, RITALIN LA ®, METADATE CD ®or FDA-approved generic equivalents.

Symptoms of ADHD were evaluated on a weekly basis by clinicians using the ADHD Rating Scale (ADHD-RS-IV), which includes both hyperactive/impulsive and inattentive subscales. The primary efficacy outcome was the change from baseline to endpoint in ADHD-RS-IV total scores. Endpoint was defined as the last post-randomization treatment week prior to dose tapering for which a valid score was obtained (up to Week 8).

Mean reductions in ADHD-RS-IV total scores at endpoint were statistically significantly greater for guanfacine extended-release tablets given in combination with a psychostimulant compared to placebo given with a psychostimulant for Study 3, for both morning and evening guanfacine extended-release tablets dosing (see Table 17). Nearly two-thirds (64.2%) of patients reached optimal doses in the 0.05-0.12 mg/kg/day range.

Studies 4, 5 and 6: Flexible-dose Guanfacine Extended-Release Tablets Monotherapy

Study 4 (314 study) was a double-blind, randomized, placebo-controlled, dose-optimization study, in which efficacy of once daily dosing (morning or evening) with guanfacine extended-release tablets (1 mg, 2 mg, 3 mg, and 4 mg) was evaluated for 8 weeks in children aged 6 to 12 years (n=340).

Signs and symptoms of ADHD were evaluated on a once weekly basis using the clinician administered and scored ADHD Rating Scale (ADHD-RS-IV), which includes both hyperactive/impulsive and inattentive subscales. The primary efficacy outcome was the change from baseline score at endpoint on the ADHD-RS-IV total scores. Endpoint was defined as the last post-randomization treatment week for which a valid score was obtained prior to dose tapering (up to Week 8).

Mean reductions in ADHD-RS-IV total scores at endpoint were statistically significantly greater for guanfacine extended-release tablets compared to placebo in both AM and PM dosing groups of guanfacine extended-release tablets (see Table 17).

Study 5 (312 study) was a 15-week, double-blind, randomized, placebo-controlled, dose-optimization study conducted in adolescents aged 13 to 17 years (n=314) to evaluate the efficacy and safety of guanfacine extended-release tablets (1-7 mg/day; optimized dose range of 0.05-0.12 mg/kg/day) in the treatment of ADHD as measured by the ADHD Rating Scale-IV (ADHD-RS-IV). Patients receiving guanfacine extended-release tablets showed statistically significantly greater improvement on the ADHD-RS-IV total score compared with patients receiving placebo (see Table 17).

Study 6 (316 study) was a 12-week (for children aged 6 to 12) or 15-week (for adolescents aged 13 to 17), randomized, double-blind, parallel-group, placebo- and active-reference, dose-optimization study conducted in pediatric patients (children and adolescents aged 6 to 17 years old inclusive) (n=337) to assess the efficacy and safety of once-daily dosing (children: 1-4 mg/day, adolescents: 1-7 mg/day; optimized dose range of 0.05 to 0.12 mg/kg/day) in the treatment of ADHD. Guanfacine extended-release tablets were statistically superior to placebo on symptoms of ADHD in patients 6 to 17 years as measured by change from baseline in ADHD-RS-IV total scores (see Table 17).

SD: standard deviation; SE: standard error; LS Mean: least-squares mean; CI: unadjusted confidence interval.
aTreatment was given in combination with a psychostimulant.
bDifference (drug minus placebo) in least-squares mean change from baseline.
*Doses statistically significantly superior to placebo.

Study 7: Long-Term Maintenance of Guanfacine Extended-Release Tablets Efficacy

Study 7 (315 study) was a double-blind, placebo-controlled, randomized withdrawal trial in pediatric patients aged 6 to 17 years with DSM-IV-TR diagnosis of ADHD. The study consisted of an open-label phase, including a 7-week dose optimization period to titrate patients to an optimal dose (maximum 4 mg/day for children and 7 mg/day for adolescents; optimized dose range: 0.05 to 0.12 mg/kg/day) and a 6-week dose maintenance period. There were 526 patients included in the open-label phase. Among those, 315 patients who met response criteria in the open-label phase were then randomized (1:1, guanfacine extended-release tablets: placebo) in a 26-week, double-blind, randomized withdrawal phase. The response criteria were defined by ≥30% reduction in ADHD-RS-IV total score and a Clinical Global Impression-Improvement (CGI-I) score of 1 or 2 during the open-label phase. A statistically significantly lower proportion of treatment failures occurred among guanfacine extended-release tablets patients compared to placebo at the end of the randomized withdrawal period (Figure 4). Treatment failure was defined as a ≥50% increase (worsening) in ADHD-RS-IV total score and a ≥2-point increase in Clinical Global Impression-Severity (CGI-S) score. Patients who met the treatment failure criteria on two consecutive visits or discontinued for any reason were classified as treatment failure.

Figure 4. Kaplan-Meier Estimation of Proportion of Patients with Treatment Failure for Children and Adolescents Ages 6 to 17 (Study 7)

Dosing and Administration

Instruct patients to swallow guanfacine extended-release tablets whole with water, milk or other liquid. Tablets should not be crushed, chewed or broken prior to administration because this may increase the rate of release of the active drug. Patients should not take guanfacine extended-release tablets together with a high-fat meal, since this can raise blood levels of guanfacine extended-release tablets. Instruct the parent or caregiver to supervise the child or adolescent taking guanfacine extended-release tablets and to keep the bottle of tablets out of reach of children.

Advise patients not to abruptly discontinue guanfacine extended-release tablets as abrupt discontinuation can result in clinically significant rebound hypertension. Concomitant stimulant use and abrupt discontinuation of guanfacine extended-release tablets may increase this hypertensive response. Instruct patients on how to properly taper the dose to minimize the risk of rebound hypertension  [see Dosage and Administration (2.5)and Warnings and Precautions (5.4)].

Adverse Reactions

Advise patients that sedation can occur, particularly early in treatment or with dose increases. Caution against operating heavy equipment or driving until they know how they respond to treatment with guanfacine extended-release tablets [see Warnings and Precautions (5.2)] . Headache and abdominal pain can also occur. If any of these symptoms persist, or other symptoms occur, the patient should be advised to discuss the symptoms with the health care provider. 

Advise patients to avoid becoming dehydrated or overheated, which may potentially increase the risks of hypotension and syncope [see Warnings and Precautions (5.1)] . Advise patients to avoid use with alcohol.

Pregnancy Registry

Advise patients that there is a pregnancy exposure registry that monitors pregnancy outcomes in patients exposed to guanfacine extended-release tablets during pregnancy [ see Use in Specific Populations (8.1)] .

Lactation

Advise breastfeeding mothers to monitor infants exposed to guanfacine through breastmilk for sedation, lethargy and poor feeding [see Use in Specific Populations (8.2)] .

Manufactured by:
Yichang Humanwell Oral Solid Dosage Plant
Yichang, Hubei, China 443112

Distributed by:
Slate Run Pharmaceuticals, LLC
Columbus, Ohio 43215

Revised: 12/2020