The starting dosage of ONYDA XR is 0.1 mg orally once daily at bedtime with or without food [see Clinical Pharmacology ( 12.3 )]. Titrate the dose of ONYDA XR in increments of 0.1 mg per day at weekly intervals depending on clinical response up to the maximum recommended dosage of 0.4 mg once daily at bedtime.

Doses of ONYDA XR higher than 0.4 mg once daily were not evaluated in clinical trials for ADHD and are not recommended.

When ONYDA XR is added to a CNS stimulant, adjust the dose of the CNS stimulant depending on the clinical response to ONYDA XR.

Instruct patients to read the “Instructions for Use” for complete administration instructions.

• Use the oral dosing dispenser and bottle adapter provided with ONYDA XR.
• Ensure that the bottle adapter is firmly inserted into the bottle before first use and keep the adapter in place for the duration of the usage of the bottle.
• Gently shake ONYDA XR with a smooth up and down motion (to avoid foaming) for at least 10 seconds before each administration.
• Discard any unused ONYDA XR remaining in the bottle after 60 days of first opening the bottle.

For patients switching from another clonidine product, discontinue that treatment, and titrate with ONYDA XR using the titration schedule [see Dosage and Administration ( 2.1 )]. Do not substitute for other clonidine products on a milligram-per-milligram basis because of differing pharmacokinetic profiles [see Clinical Pharmacology ( 12.3 )].

When discontinuing ONYDA XR, taper the total daily dose in decrements of no more than 0.1 mg every 3 to 7 days to avoid rebound hypertension [see Warnings and Precautions ( 5.3 )].

If a dose of ONYDA XR is missed, skip that dose and take the next dose as scheduled. Do not take more than the prescribed total daily amount of ONYDA XR in any 24-hour period.

Treatment with ONYDA XR 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 ONYDA XR 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 [see Drug Interactions ( 7 )].

Somnolence and sedation were commonly reported adverse reactions in clinical studies with clonidine hydrochloride extended-release tablets. 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 reaction. 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 plus a stimulant versus 7% treated with placebo plus a stimulant reported somnolence.

Before using ONYDA XR with other centrally active depressants (such as phenothiazines, barbiturates, or benzodiazepines), consider the potential for additive sedative effects [see Drug Interactions ( 7 )]. Caution patients against operating heavy equipment or driving until they know how they respond to treatment with ONYDA XR. Advise patients to avoid use with alcohol.

Abrupt discontinuation of ONYDA XR can cause rebound hypertension. In adults with hypertension, sudden cessation of clonidine extended-release formulation treatment in the 0.2 to 0.6 mg per 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 pediatric patients with ADHD have been conducted; however, to minimize the risk of rebound hypertension, gradually reduce the dose of ONYDA XR in decrements of no more than 0.1 mg every 3 to 7 days. Patients should be instructed not to discontinue ONYDA XR therapy without consulting their physician due to the potential risk of withdrawal effects.

In patients who have developed localized contact sensitization to clonidine transdermal system, continuation of clonidine transdermal system or use of oral ONYDA XR therapy may be associated with the development of a generalized skin rash.

In patients who develop an allergic reaction from clonidine transdermal system, use of ONYDA XR may also elicit an allergic reaction (including generalized rash, urticaria, or angioedema).

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 intravenous (IV) atropine, IV isoproterenol, and temporary cardiac pacing while taking clonidine. Titrate ONYDA XR slowly and monitor vital signs frequently in patients with cardiac conduction abnormalities or patients concomitantly treated with other sympatholytic drugs.

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 safety of ONYDA XR for the treatment of ADHD in pediatric patients 6 years and older is based upon adequate and well-controlled studies of clonidine hydrochloride extended-release tablets (referred to as “clonidine hydrochloride extended-release” in this section). The safety results of these adequate and well-controlled studies of clonidine hydrochloride extended-release tablets are presented below.

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

A third clonidine hydrochloride extended-release ADHD clinical study (Study 3) evaluated 135 pediatric patients 6 to 17 years of age in a 40-week placebo-controlled randomized‑withdrawal study.

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

Study 1 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 in pediatric patients 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 Reactions Leading to Discontinuation of clonidine hydrochloride extended-release: 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 1.

Table 1:  Common Adverse Reactions Occurring in ≥2%of Patients Treated with Clonidine Hydrochloride Extended-Release Tablets and Greater than the Rate of Placebo in the Fixed-Dose Monotherapy Trial -Treatment Period (Study 1)

Preferred Term	Clonidine hydrochloride extended-release tablets 0.2 mg/day N=76 (%)	Clonidine hydrochloride extended-release tablets 0.4 mg/day N=78 (%)	Placebo N=76 (%)
PSYCHIATRIC DISORDERS Somnolence* Nightmare Emotional Disorder Aggression Tearfulness Enuresis Sleep Terror Poor Quality Sleep	38 4 4 3 1 0 3 0	31 9 4 1 3 4 0 3	4 0 1 0 0 0 0 1
NERVOUS SYSTEM DISORDERS Headache Insomnia Tremor Abnormal Sleep-Related Event	20 5 1 3	13 6 4 1	16 1 0 0
GASTRO-INTESTINAL DISORDERS Upper Abdominal Pain Nausea Constipation Dry Mouth	15 4 1 0	10 5 6 5	12 3 0 1
GENERAL DISORDERS Fatigue† Irritability	16 9	13 5	1 4
CARDIAC DISORDERS Dizziness Bradycardia	7 0	3 4	5 0
INVESTIGATIONS Increased Heart Rate	0	3	0
METABOLISM AND NUTRITION DISORDERS Decreased Appetite	3	4	4

* Somnolence includes the terms "somnolence" and "sedation".

† Fatigue includes the terms "fatigue" and "lethargy".

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 2.

Table 2:  Common Adverse Reactions Occurring in ≥2% of Patients Treated with Clonidine Hydrochloride Extended-Release Tablets and Greater than the Rate of Placebo in the Fixed-Dose Monotherapy Trial -Taper Period* (Study 1)

Preferred Term	Clonidine hydrochloride extended-release tablets 0.2 mg/day N=76 (%)	Clonidine hydrochloride extended-release tablets 0.4 mg/day N=78 (%)	Placebo N=76 (%)
Abdominal Pain Upper	0	6	3
Headache	5	2	3
Gastrointestinal Viral	0	5	0
Somnolence	2	3	0
Heart Rate Increased	0	3	0
Otitis Media Acute	3	0	0

* Taper Period: 0.2 mg dose, week 8; 0.4 mg dose, weeks 6-8; Placebo dose, weeks 6-8

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

Study 2 was a short-term, randomized, double-blind, placebo-controlled study of a flexible dose of clonidine hydrochloride extended-release as adjunctive therapy to a psychostimulant in pediatric patients 6 to 17 years of age who met DSM-IV criteria for ADHD hyperactive or combined inattentive/hyperactive subtypes, during which clonidine hydrochloride extended‑release was initiated at 0.1 mg/day and titrated up to 0.4 mg/day over a 3-week period. Most clonidine hydrochloride extended-release 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 Reactions Leading to Discontinuation: There was one patient in the clonidine hydrochloride extended-release + stimulant (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 3.

Table 3:   Common Adverse Reactions Occurring in ≥2% of Patients Treated with Clonidine Hydrochloride Extended-Release Tablets and Greater than the Rate of Placebo in the Flexible-Dose Adjunctive to Stimulant Therapy Trial -Treatment Period (Study 2)

Preferred Term	Clonidine hydrochloride extended-release tablets + Stimulant N=102 (%)	PBO+Stimulant N=96 (%)
PSYCHIATRIC DISORDERS Somnolence+ Aggression Affect Lability Emotional Disorder	19 2 2 2	7 1 1 0
GENERAL DISORDERS Fatigue† Irritability	14 2	4 7
NERVOUS SYSTEM DISORDERS Headache Insomnia	7 4	12 3
GASTRO-INTESTINAL DISORDERS Upper Abdominal Pain	7	4
RESPIRATORY DISORDERS Nasal Congestion	2	2
METABOLISM AND NUTRITION DISORDERS Decreased Appetite	6	3
CARDIAC DISORDERS Dizziness	5	1

  ⁺Somnolence includes the terms: "somnolence" and "sedation"

^† Fatigue includes the terms "fatigue" and "lethargy"

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 4.

Table 4:  Common Adverse Reactions Occurring in ≥2% of Patients Treated with Clonidine Hydrochloride Extended-Release Tablets and Greater than the Rate of Placebo in the Flexible-Dose Adjunctive to Stimulant Therapy Trial -Taper Period⁺ (Study 2)

Preferred Term	Clonidine hydrochloride extended-release tablets + Stimulant N=102 (%)	Placebo+Stimulant N=96 (%)
Nasal Congestion	4	2
Headache	3	1
Irritability	3	2
Throat Pain	3	1
Gastroenteritis Viral	2	0
Rash	2	0

⁺Taper Period: weeks 6-8

Adverse Reactions Leading to Discontinuation

Thirteen percent (13%) of patients receiving clonidine hydrochloride extended-release discontinued from the pediatric monotherapy study due to adverse reactions, compared to 1% in the placebo group. The most common adverse reactions leading to discontinuation of clonidine hydrochloride extended-release monotherapy treated patients were 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 0.2 mg/day and -8.8 mmHg on clonidine hydrochloride extended-release 0.4 mg/day. The maximum placebo-subtracted mean change in diastolic blood pressure was -4.0 mmHg on clonidine hydrochloride extended-release 0.2 mg/day and -7.3 mmHg on clonidine hydrochloride extended-release 0.4 mg/day. The maximum placebo-subtracted mean change in heart rate was ‑4.0 beats per minute on clonidine hydrochloride extended-release 0.2 mg/day and -7.7 beats per minute on clonidine hydrochloride extended-release 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 0.2 mg/day and -5.6 mmHg on clonidine hydrochloride extended-release 0.4 mg/day. The maximum placebo-subtracted mean change in diastolic blood pressure was +3.3 mmHg on clonidine hydrochloride extended-release 0.2 mg/day and -5.4 mmHg on clonidine hydrochloride extended-release 0.4 mg/day. The maximum placebo-subtracted mean change in heart rate was -0.6 beats per minute on clonidine hydrochloride extended-release 0.2 mg/day and -3.0 beats per minute on clonidine hydrochloride extended-release 0.4 mg/day.

The following adverse reactions have been identified during post-approval use of clonidine hydrochloride extended-release tablets (and excludes those already mentioned in Section 6.1). 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.

Psychiatric: hallucinations

Cardiovascular: Q-T prolongation

Pregnancy Exposure Registry

There is a pregnancy exposure registry that monitors pregnancy outcomes in women exposed to ADHD medications, including ONYDA XR, during pregnancy. Healthcare providers are encouraged to advise patients to register by calling the National Pregnancy Registry for Psychiatric Medications at 1-866-961-2388 or visiting online at 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.

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 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 ONYDA XR and any potential adverse effects on the breastfed child from ONYDA XR or from the underlying maternal condition. Exercise caution when ONYDA XR is administered to a nursing woman.

Clinical Considerations

Monitor breastfeeding infants exposed to ONYDA XR through breast milk for symptoms of hypotension and/or bradycardia such as sedation, lethargy, tachypnea, and poor feeding.

Infertility

Findings in animal studies revealed that ONYDA XR may impair fertility in females and males of reproductive potential [see Nonclinical Toxicology ( 13.1 )].

The safety and efficacy of clonidine hydrochloride extended-release in the treatment of ADHD have been established in pediatric patients 6 to 17 years of age. Use of clonidine hydrochloride extended-release 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.

The impact of renal impairment on the pharmacokinetics of clonidine in pediatric patients has not been assessed. The initial dosage of ONYDA XR 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 ONYDA XR following dialysis.

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.

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.

Immediate-release clonidine hydrochloride, extended-release clonidine hydrochloride tablets, and ONYDA XR have different pharmacokinetic characteristics. Dose substitution on a milligram for milligram basis will result in differences in exposures [see Dosage and Administration ( 2.3 )].

Absorption

Following a single 0.2 mg dose of ONYDA XR in 20 healthy adult subjects under fasting conditions in a crossover study, the median (range) time to peak plasma concentrations (T_max) for clonidine was 7.50 (4 –17) hours after dosing. Peak concentration (C_max) was 95.6% of the C_max of clonidine extended-release tablet 0.1 mg administered at 0 and 12 hours under fasting conditions. The relative bioavailability of ONYDA XR compared with an equal dose of clonidine extended-release tablet was 96.1%.

After oral administration of 0.2 mg of ONYDA XR once daily over 5 days under fasted conditions in healthy adult subjects, the peak steady state plasma concentration (C_max.ss) was 107.9%, and steady state relative bioavailability (AUC_t, ss) was 97.7% compared with 0.1 mg of clonidine extended-release tablet administered twice daily under fasting conditions. The minimum concentration at steady state (Cmin,ss) of ONYDA XR was about 26% lower than that of the equal dose of clonidine extended-release tablet.

Following oral administration of an immediate release formulation in healthy adult subjects, plasma clonidine concentration peaks in approximately 3 to 5 hours.

A comparison across studies suggests that the C_max is 50% lower for clonidine hydrochloride extended-release tablets compared to immediate-release clonidine hydrochloride.

Effect of Food

Food had no effect on plasma exposures of clonidine after administration of ONYDA XR (see Figure 1).

Figure 1:       Mean Clonidine Concentration-Time Profiles After Single Dose Administration

  

Elimination

The plasma half-life of immediate-release clonidine ranges from 12 to 16 hours. The half-life increases up to 41 hours in patients with severe impairment of renal function.

Metabolism

About 50% of the absorbed dose is metabolized in the liver.

Excretion

Following oral administration about 40% to 60% of the absorbed dose is recovered in the urine as unchanged drug in 24 hours. Although studies of the effect of renal impairment and studies of clonidine excretion have not been performed with ONYDA XR, results are expected to be similar to those of the immediate-release formulation.

Specific Populations

Pediatric patients                                                                                   

Plasma clonidine concentrations in pediatric patients 6 to 17 years (0.1 mg twice daily and 0.2 mg twice daily of clonidine hydrochloride extended-release tablets) with ADHD are greater than those of adults with hypertension, with pediatric patients 6 to 17 years receiving higher doses on a mg/kg basis. Body weight normalized clearance (CL/F) in pediatric patients aged 6 to 17 years 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" events (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.

Drug Interaction Studies

Alcohol: In an in vitro alcohol-induced dose dumping study, a significantly faster and more variable ONYDA XR drug release was observed in the presence of 20% alcohol, but not with 5% or 10% alcohol, when compared to 0% alcohol.

Carcinogenesis

Clonidine hydrochloride 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 1,620 (male rats), 2,040 (female rats), or 2,500 (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 2,000 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.