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.
Table 2 Common Adverse Reactions in the Fixed-Dose Monotherapy Trial - Treatment Period (Study 1) | Percentage of Patients Reporting Event |
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% |
GASTROINTESTINAL 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 3.
Table 3 Common Adverse Reactions in the Fixed-Dose Monotherapy Trial - Taper Period* (Study 1) | Percentage of Patients Reporting Event |
| 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 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.
Table 4 Common Adverse Reactions in the Flexible-Dose Adjunctive to Stimulant Therapy Trial - Treatment Period (Study 2) | Percentage of Patients Reporting Event |
Preferred Term | Clonidine Hydrochloride Extended-Release Tablets+STM (N=102) | PBO+STM (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% |
GASTROINTESTINAL 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 5.
Table 5 Common Adverse Reactions in the Flexible-Dose Adjunctive to Stimulant Therapy Trial - Taper Period* (Study 2) | Percentage of Patients Reporting Event |
| Preferred Term | Clonidine Hydrochloride Extended-Release Tablets+STM (N=102) | PBO+STM (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 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.