Clonidine hydrochloride 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 Dosing Information

Clonidine hydrochloride extended-release tablets is an extended-release tablet to be taken orally with or without food. Swallow tablets whole. Do not crush, chew, or break tablets because this will increase the rate of clonidine release.

Due to the lack of controlled clinical trial data and differing pharmacokinetic profiles, substitution of clonidine hydrochloride extended-release tablets for other clonidine products on a mg-per-mg basis is not recommended [see Clinical Pharmacology (12.3)].

2.2 Dose Selection

The dose of clonidine hydrochloride extended-release tablets, administered either as monotherapy or as adjunctive therapy to a psychostimulant, should be individualized according to the therapeutic needs and response of the patient. Dosing should be initiated with one 0.1 mg tablet at bedtime, and the daily dosage should be adjusted in increments of 0.1 mg/day at weekly intervals until the desired response is achieved. Doses should be taken twice a day, with either an equal or higher split dosage being given at bedtime (see Table 1).

 Table 1 Clonidine hydrochloride extended-release tablets Dosing Guidance

Doses of clonidine hydrochloride extended-release tablets higher than 0.4 mg/day (0.2 mg twice daily) were not evaluated in clinical trials for ADHD and are not recommended.

When clonidine hydrochloride extended-release tablets is being added-on to a psychostimulant, the dose of the psychostimulant can be adjusted depending on the patient's response to clonidine hydrochloride extended-release tablets.

2.3 Discontinuation

When discontinuing clonidine hydrochloride extended-release tablets, the total daily dose should be tapered in decrements of no more than 0.1 mg every 3 to 7 days to avoid rebound hypertension [see Warnings and Precautions (5.3)].

2.4 Missed Doses

If patients miss a dose of clonidine hydrochloride extended-release tablets, they should skip that dose and take the next dose as scheduled. Do not take more than the prescribed total daily amount of clonidine hydrochloride extended-release tablets in any 24-hour period.

Clonidine hydrochloride extended-release tablets are available as 0.1 mg strength extended-release tablets. The 0.1 mg tablets are white or off white, non-scored, round biconvex with debossing on one side. Clonidine hydrochloride extended-release tablets must be swallowed whole and never crushed, cut or chewed.

Clonidine hydrochloride extended-release tablets are contraindicated in patients with a history of a hypersensitivity reaction to clonidine. Reactions have included generalized rash, urticaria, and angioedema [see Adverse Reactions (6)].

5.1 Hypotension/Bradycardia

Treatment with clonidine hydrochloride extended-release tablets can cause dose-related decreases in blood pressure and heart rate [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 clonidine hydrochloride 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. In patients that completed 5 weeks of therapy in a controlled, fixed dose pediatric monotherapy study, 31% of patients treated with 0.4 mg/day and 38% treated with 0.2 mg/day versus 4% of placebo treated patients reported somnolence as an adverse event. In patients that completed 5 weeks of therapy in a controlled flexible dose pediatric adjunctive to stimulants study, 19% of patients treated with clonidine hydrochloride extended-release tablets +stimulant versus 7% treated with placebo+stimulant reported somnolence. Before using clonidine hydrochloride extended-release tablets with other centrally active depressants (such as phenothiazines, barbiturates, or benzodiazepines), consider the potential for additive sedative effects. Caution patients against operating heavy equipment or driving until they know how they respond to treatment with clonidine hydrochloride extended-release tablets. Advise patients to avoid use with alcohol.

5.3 Rebound Hypertension

Abrupt discontinuation of clonidine hydrochloride extended-release tablets can cause rebound hypertension. In adults with hypertension, sudden cessation of clonidine hydrochloride extended- release formulation treatment in the 0.2 to 0.6 mg/day range resulted in reports of headache, tachycardia, nausea, flushing, warm feeling, brief lightheadedness, tightness in chest, and anxiety. In adults with hypertension, sudden cessation of treatment with immediate-release clonidine has, in some cases, resulted in symptoms such as nervousness, agitation, headache, and tremor accompanied or followed by a rapid rise in blood pressure and elevated catecholamine concentrations in the plasma.

No studies evaluating abrupt discontinuation of clonidine hydrochloride extended-release tablets in children with ADHD have been conducted; however, to minimize the risk of rebound hypertension, gradually reduce the dose of clonidine hydrochloride extended-release tablets in decrements of no more than 0.1 mg every 3 to 7 days. Patients should be instructed not to discontinue clonidine hydrochloride extended-release tablets therapy without consulting their physician due to the potential risk of withdrawal effects.

5.4 Allergic Reactions

In patients who have developed localized contact sensitization to clonidine transdermal system, continuation of clonidine transdermal system or substitution of oral clonidine hydrochloride extended-release tablets therapy may be associated with the development of a generalized skin rash.

In patients who develop an allergic reaction from clonidine transdermal system, substitution of oral clonidine hydrochloride extended-release tablets may also elicit an allergic reaction (including generalized rash, urticaria, or angioedema).

5.5 Cardiac Conduction Abnormalities

The sympatholytic action of clonidine may worsen sinus node dysfunction and atrioventricular (AV) block, especially in patients taking other sympatholytic drugs. There have been post-marketing reports of patients with conduction abnormalities and/or taking other sympatholytic drugs who developed severe bradycardia requiring IV atropine, IV isoproterenol, and temporary cardiac pacing while taking clonidine. Titrate clonidine hydrochloride extended-release tablets slowly and monitor vital signs frequently in patients with cardiac conduction abnormalities or patients concomitantly treated with other sympatholytic drugs.

The following serious adverse reactions are described in greater detail elsewhere in labeling:

• Hypotension/bradycardia [see Warnings and Precautions (5.1)]
• Sedation and somnolence [see Warnings and Precautions (5.2)]
• Rebound hypertension [see Warnings and Precautions (5.3)]
• Allergic reactions [see Warnings and Precautions (5.4)]
• Cardiac Conduction Abnormalities [see Warnings and Precautions (5.5)]

6.1 Clinical Trial 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.

Two clonidine hydrochloride extended-release tablets ADHD clinical studies (Study 1, CLON-301 and Study 2, CLON-302) evaluated 256 patients in two 8-week placebo-controlled studies. 

A third clonidine hydrochloride extended-release tablets ADHD clinical study (Study 3, SHN-KAP-401) evaluated 135 children and adolescents in a 40- week placebo-controlled randomized-withdrawal study.

Study 1: Fixed-dose clonidine hydrochloride extended-release tablets Monotherapy

Study 1 (CLON-301) was a short-term, multi-center, randomized, double-blind, placebo-controlled study of two fixed doses (0.2 mg/day or 0.4 mg/day) of clonidine hydrochloride extended-release tablets in children and adolescents (6 to 17 years of age) who met DSM-IV criteria for ADHD hyperactive or combined inattentive/hyperactive subtypes.

Most Common Adverse Reactions (incidence of >=5% and at least twice the rate of placebo): somnolence, fatigue, irritability, insomnia, nightmare, constipation, dry mouth.

Adverse Events Leading to Discontinuation of clonidine hydrochloride extended-release tablets –Five patients (7%) in the low dose group (0.2 mg), 15 patients (20%) in the high dose group (0.4 mg), and 1 patient in the placebo group (1%) reported adverse reactions that led to discontinuation. The most common adverse reactions that led to discontinuation were somnolence and fatigue.

Commonly observed adverse reactions (incidence of >=2% in either active treatment group and greater than the rate on placebo) during the treatment period are listed in Table 2.

Commonly observed adverse reactions (incidence of >=2% in either active treatment group and greater than the rate on placebo) during the taper period are listed in Table 3.

Study 2: Flexible-dose clonidine hydrochloride extended-release tablets as Adjunctive Therapy to Psychostimulants

Study 2 (CLON-302) was a short-term, randomized, double-blind, placebo-controlled study of a flexible dose of clonidine hydrochloride extended-release tablets as adjunctive therapy to a psychostimulant in children and adolescents (6 to 17 years) who met DSM-IV criteria for ADHD hyperactive or combined inattentive/hyperactive subtypes, during which clonidine hydrochloride extended-release tablets were initiated at 0.1 mg/day and titrated up to 0.4 mg/day over a 3-week period. Most clonidine hydrochloride extended-release tablets treated patients (75.5%) were escalated to the maximum dose of 0.4 mg/day.

Most Common Adverse Reactions (incidence of >=5% and at least twice the rate of placebo): somnolence, fatigue, decreased appetite, dizziness.

Adverse Events Leading to Discontinuation – There was one patient in the CLON+STM group (1%) who discontinued because of an adverse event (severe bradyphrenia, with severe fatigue).

Commonly observed adverse reactions (incidence of >=2% in the treatment group and greater than the rate on placebo) during the treatment period are listed in Table 4.

Commonly observed adverse reactions (incidence of >=2% in the treatment group and greater than the rate on placebo) during the taper period are listed in Table 5.

Adverse Reactions Leading to Discontinuation

Thirteen percent (13%) of patients receiving clonidine hydrochloride extended-release tablets discontinued from the pediatric monotherapy study due to adverse events, compared to 1% in the placebo group. The most common adverse reactions leading to discontinuation of clonidine hydrochloride extended-release tablets monotherapy treated patients were from somnolence/sedation (5%) and fatigue (4%).

Effect on Blood Pressure and Heart Rate

In patients that completed 5 weeks of treatment in a controlled, fixed-dose monotherapy study in pediatric patients, during the treatment period the maximum placebo-subtracted mean change in systolic blood pressure was -4.0 mmHg on clonidine hydrochloride extended-release tablets 0.2 mg/day and -8.8 mmHg on clonidine hydrochloride extended-release tablets 0.4 mg/day. The maximum placebo-subtracted mean change in diastolic blood pressure was -4.0 mmHg on clonidine hydrochloride extended-release tablets 0.2 mg/day and -7.3 mmHg on clonidine hydrochloride extended-release tablets 0.4 mg/day. The maximum placebo-subtracted mean change in heart rate was -4.0 beats per minute on clonidine hydrochloride extended-release tablets 0.2 mg/day and -7.7 beats per minute on clonidine hydrochloride extended-release tablets 0.4 mg/day.

During the taper period of the fixed-dose monotherapy study the maximum placebo-subtracted mean change in systolic blood pressure was +3.4 mmHg on clonidine hydrochloride extended-release tablets 0.2 mg/day and -5.6 mmHg on clonidine hydrochloride extended-release tablets 0.4 mg/day. The maximum placebo-subtracted mean change in diastolic blood pressure was +3.3 mmHg on clonidine hydrochloride extended-release tablets 0.2 mg/day and -5.4 mmHg on clonidine hydrochloride extended-release tablets 0.4 mg/day. The maximum placebo-subtracted mean change in heart rate was -0.6 beats per minute on clonidine hydrochloride extended-release tablets 0.2 mg/day and -3.0 beats per minute on clonidine hydrochloride extended-release tablets 0.4 mg/day.

6.2 Postmarketing Experience

The following adverse reactions have been identified during post-approval use of clonidine hydrochloride extended-release tablets. 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.

These events exclude those already mentioned in 6.1:

Psychiatric: hallucinations

Cardiovascular: Q-T prolongation

The following have been reported with other oral immediate release formulations of clonidine:

Table 6 Clinically Important Drug Interactions

8.1 Pregnancy

Pregnancy Exposure Registry

There is a pregnancy exposure registry that monitors pregnancy outcomes in women exposed to ADHD medications, including clonidine hydrochloride 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 or visiting https://womensmentalhealth.org/adhd-medications/.

Risk Summary

Prolonged experience with clonidine in pregnant women over several decades, based on published literature, including controlled trials, a retrospective cohort study and case reports, have not identified a drug associated risk of major birth defects, miscarriage, and adverse maternal or fetal outcomes. In animal embryofetal studies, increased resorptions were seen in rats and mice administered oral clonidine hydrochloride from implantation through organogenesis at 10 and 5 times, respectively, the maximum recommended human dose (MRHD) given to adolescents on a mg/m2 basis. No developmental effects were seen in rabbits administered oral clonidine hydrochloride during organogenesis at doses up to 3 times the MRHD (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 background risk of major birth defects and miscarriages in clinically recognized pregnancies is 2 to 4% and 15 to 20%, respectively.

Data

Animal Data

Oral administration of clonidine hydrochloride to pregnant rabbits during the period of embryo/fetal organogenesis at doses of up to 80 mcg/kg/day (approximately 3 times the oral maximum recommended daily dose [MRHD] of 0.4 mg/day given to adolescents on a mg/m2 basis) produced no developmental effects. In pregnant rats, however, doses as low as 15 mcg/kg/day (1/3 the MRHD given to adolescents on a mg/m2 basis) were associated with increased resorptions in a study in which dams were treated continuously from 2 months prior to mating and throughout gestation. Increased resorptions were not associated with treatment at the same or at higher dose levels (up to 3 times the MRHD) when treatment of the dams was restricted to gestation days 6-15. Increases in resorptions were observed in both rats and mice at 500 mcg/kg/day (10 and 5 times the MRHD in rats and mice, respectively) or higher when the animals were treated on gestation days 1-14; 500 mcg/kg/day was the lowest dose employed in this study.

8.2 Lactation

Risk Summary

Based on published lactation studies, clonidine hydrochloride is present in human milk at relative infant doses ranging from 4.1 to 8.4% of the maternal weight-adjusted dosage. Although in most cases, there were no reported adverse effects in breastfed infants exposed to clonidine, there is one case report of sedation, hypotonia, and apnea in an infant exposed to clonidine through breast milk. If an infant is exposed to clonidine hydrochloride through breastmilk, monitor for symptoms of hypotension and bradycardia, such as sedation, lethargy, tachypnea and poor feeding (see Clinical Considerations).The developmental and health benefits of breastfeeding should be considered along with the mother's clinical need for clonidine hydrochloride extended-release tablets and any potential adverse effects on the breastfed child from clonidine hydrochloride extended-release tablets or from the underlying maternal condition. Exercise caution when clonidine hydrochloride extended-release tablets are administered to a nursing woman.

Clinical Considerations

Monitor breastfeeding infants exposed to clonidine hydrochloride extended-release tablets through breast milk for symptoms of hypotension and/or bradycardia such as sedation, lethargy, tachypnea, and poor feeding.

8.3 Females and Males of Reproductive Potential

Infertility

Based on findings in Animal studies revealed that clonidine hydrochloride extended-release tablets may impair fertility in females and males of reproductive potential [see Nonclinical Toxicology (13.1)].

8.4 Pediatric Use

The safety and efficacy of clonidine hydrochloride extended-release tablets in the treatment of ADHD have been established in pediatric patients 6 to 17 years of age. Use of clonidine hydrochloride extended-release tablets in pediatric patients 6 to 17 years of age is supported by three adequate and well-controlled studies; a short-term, placebo-controlled monotherapy trial, a short- term adjunctive therapy trial and a longer-term randomized monotherapy trial [see Clinical Studies (14)]. Safety and efficacy in pediatric patients below the age of 6 years has not been established.

Juvenile Animal Data

In studies in juvenile rats, clonidine hydrochloride alone or in combination with methylphenidate had an effect on bone growth at clinically relevant doses and produced a slight delay in sexual maturation in males at 3 times the maximum recommended human dose (MRHD) for clonidine and methylphenidate.

In a study where juvenile rats were treated orally with clonidine hydrochloride from day 21 of age to adulthood, a slight delay in onset of preputial separation (delayed sexual maturation) was seen in males treated with 300 mcg/kg/day, which is approximately 3 times the MRHD of 0.4 mg/day on a mg/m2 basis.  The no-effect dose was 100 mcg/kg/day, which is approximately equal to the MRHD. There was no drug effects on fertility or on other measures of sexual or neurobehavioral development.

In a  study where juvenile rats were treated with clonidine alone (300 mcg/kg/day) or in combination with methylphenidate (10 mg/kg/day in females and 50/30 mg/kg/day in males; the dose was lowered from 50 to 30 mg/kg/day in males due to self-injurious behavior during the first week of treatment) from day 21 of age to adulthood, decreases in bone mineral density and mineral content were observed in males treated with 300 mcg/kg/day clonidine alone and in combination with 50/30 mg/kg/day methylphenidate and a decrease in femur length was observed in males treated with the combination at the end of the treatment period. These doses are approximately 3 times the MRHD of 0.4 mg/day clonidine and 54 mg/day methylphenidate on a mg/m2 basis. All these effects in male were not reversed at the end of a 4-week recovery period. In addition, similar findings were seen in males treated with a lower dose of clonidine (30 mcg/kg/day) in combination with 50 mg/kg/day of methylphenidate and a decrease in femur length was observed in females treated with clonidine alone at the end of the recovery period. These effects were accompanied by a decrease in body weight gain in treated animals during the treatment period but the effect was reversed at the end of the recovery period. A delay in preputial separation (sexual maturation) was observed in males treated with the combination treatment of 300 mcg/kg/day clonidine and 50/30 mg/kg/day methylphenidate. There was no effect on reproduction or sperm analysis in these males.

8.6 Renal Impairment

The impact of renal impairment on the pharmacokinetics of clonidine in children has not been assessed. The initial dosage of clonidine hydrochloride extended-release tablets should be based on degree of impairment. Monitor patients carefully for hypotension and bradycardia, and titrate to higher doses cautiously. Since only a minimal amount of clonidine is removed during routine hemodialysis, there is no need to give supplemental clonidine hydrochloride extended-release tablets following dialysis.

9.1 Controlled Substance

Clonidine hydrochloride extended-release tablets is not a controlled substance and has no known potential for abuse or dependence.

12.1 Mechanism of Action

Clonidine stimulates alpha2-adrenergic receptors in the brain. Clonidine is not a central nervous system stimulant. The mechanism of action of clonidine in ADHD is not known.

12.2 Pharmacodynamics

Clonidine is a known antihypertensive agent. By stimulating alpha2-adrenergic receptors in the brain stem, clonidine reduces sympathetic outflow from the central nervous system and decreases peripheral resistance, renal vascular resistance, heart rate, and blood pressure.

12.3 Pharmacokinetics

Single-dose Pharmacokinetics in Adults

Immediate-release clonidine hydrochloride and clonidine hydrochloride extended-release tablets have different pharmacokinetic characteristics; dose substitution on a milligram for milligram basis will result in differences in exposure. A comparison across studies suggests that the Cmax is 50% lower for clonidine hydrochloride extended-release tablets compared to immediate-release clonidine hydrochloride.

Following oral administration of an immediate release formulation, plasma clonidine concentration peaks in approximately 3 to 5 hours and the plasma half- life ranges from 12 to 16 hours. The half-life increases up to 41 hours in patients with severe impairment of renal function. Following oral administration about 40-60% of the absorbed dose is recovered in the urine as unchanged drug in 24 hours.

About 50% of the absorbed dose is metabolized in the liver. Although studies of the effect of renal impairment and studies of clonidine excretion have not been performed with clonidine hydrochloride extended-release tablets, results are likely to be similar to those of the immediate release formulation.

The pharmacokinetic profile of clonidine hydrochloride extended-release tablets administration was evaluated in an open-label, three-period, randomized, crossover study of 15 healthy adult subjects who received three single-dose regimens of clonidine: 0.1 mg of clonidine hydrochloride extended-release tablets under fasted conditions, 0.1 mg of clonidine hydrochloride extended-release tablets following a high fat meal, and 0.1 mg of clonidine hydrochloride immediate-release tablets under fasted conditions. Treatments were separated by one-week washout periods.

Mean concentration-time data from the 3 treatments are shown in Table 7 and Figure 1. After administration of clonidine hydrochloride extended-release tablets, maximum clonidine concentrations were approximately 50% of the clonidine hydrochloride immediate-release tablets maximum concentrations and occurred approximately 5 hours later relative to clonidine hydrochloride immediate-release tablets. Similar elimination half-lives were observed and total systemic bioavailability following clonidine hydrochloride extended-release tablets was approximately 89% of that following clonidine hydrochloride immediate-release tablets.

Food had no effect on plasma concentrations, bioavailability, or elimination half-life.

Multiple-dose Pharmacokinetics in Children and Adolescents

Plasma clonidine concentrations in children and adolescents (0.1 mg bid and 0.2 mg bid) with ADHD are greater than those of adults with hypertension with children and adolescents receiving higher doses on a mg/kg basis. Body weight normalized clearance (CL/F) in children and adolescents was higher than CL/F observed in adults with hypertension. Clonidine concentrations in plasma increased with increases in dose over the dose range of 0.2 to 0.4 mg/day. Clonidine CL/F was independent of dose administered over the 0.2 to 0.4 mg/day dose range. Clonidine CL/F appeared to decrease slightly with increases in age over the range of 6 to 17 years, and females had a 23% lower CL/F than males. The incidence of "sedation-like" AEs (somnolence and fatigue) appeared to be independent of clonidine dose or concentration within the studied dose range in the titration study. Results from the add-on study showed that clonidine CL/F was 11% higher in patients who were receiving methylphenidate and 44% lower in those receiving amphetamine compared to subjects not on adjunctive therapy.

13.1 Carcinogenesis, Mutagenesis and Impairment of Fertility

Carcinogenesis

Clonidine HCl was not carcinogenic when administered in the diet of rats (for up to 132 weeks) or mice (for up to 78 weeks) at doses of up to 1620 (male rats), 2040 (female rats), or 2500 (mice) mcg/kg/day. These doses are approximately 20, 25, and 15 times, respectively, the maximum recommended human dose (MRHD) of 0.4 mg/day on a mg/m2 basis.

Mutagenesis

There was no evidence of genotoxicity in the Ames test for mutagenicity or mouse micronucleus test for clastogenicity.

Impairment of Fertility

In a reproduction study fertility of female rats appeared to be adversely affected at dose levels of 500 and 2000 mcg/kg/day (10 and 40 times the MRHD on a mg/ m2 basis). Lower doses have not been adequately evaluated and a no adverse effect level could not be established.