Guanfacine (Page 2 of 6)

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 may worsen sinus node dysfunction and atrioventricular (AV) block, especially in patients taking other sympatholytic drugs. Titrate guanfacine 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 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 extended-release tablets. 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 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 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 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 (mg)

Adverse Reaction Term

Placebo

(N = 149)

1 mg*

(N = 61)

2 mg

(N = 150)

3 mg

(N = 151)

4 mg

(N = 151)

All Doses of Guanfacine (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 and > rate than in placebo) in Fixed Dose Studies 1 and 2

GUANFACINE (mg)

Adverse Reaction Term

Placebo

(N = 149)

1 mg*

(N = 61)

2 mg

(N = 150)

3 mg

(N = 151)

4 mg

(N = 151)

All Doses of Guanfacine (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 and > rate than in placebo) in Fixed Dose Studies 1 and 2

GUANFACINE(mg)

Adverse Reaction Term

Placebo

(N = 149)

1 mg*

(N = 61)

2 mg

(N = 150)

3 mg

(N = 151)

4 mg

(N = 151)

All Doses of Guanfacine (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 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, stomach discomfort), rash (rash, rash generalized, rash papular), dyspepsia, increased weight, bradycardia (bradycardia, sinus bradycardia), asthma (asthma, bronchospasm, wheezing), agitation, anxiety (anxiety, nervousness), sinus arrhythmia, blood pressure increased (blood pressure increased, blood pressure diastolic increased), and first degree atrioventricular block.

* The lowest dose of 1 mg used in Study 2 was not randomized to patients weighing more than 50 kg.

a: The abdominal pain term includes abdominal pain, abdominal pain lower, abdominal pain upper, and abdominal tenderness.

b: The nightmare term includes abnormal dreams, nightmare, and sleep terror.

c: The enuresis term includes enuresis, nocturia, and urinary incontinence.

d: The affect lability term includes affect lability and mood swings.

Monotherapy Flexible Dose Trials

Table 6: Percentage of Patients Experiencing Most Common (≥ 5% and at least twice the rate for placebo) Adverse Reactions in the Monotherapy Flexible Dose Study 4

GUANFACINE

Adverse Reaction Term

Placebo

(N = 112)

AM

(N = 107)

PM

(N = 114)

All Doses of Guanfacine (N = 221)

Somnolencea

15%

57%

54%

56%

Abdominal Painb

7%

8%

19%

14%

Fatigue

3%

10%

11%

11%

Irritability

3%

7%

7%

7%

Nausea

1%

6%

5%

5%

Dizziness

3%

6%

4%

5%

Vomiting

2%

7%

4%

5%

Hypotensionc

0%

6%

4%

5%

Decreased Appetite

3%

6%

3%

4%

Enuresisd

1%

2%

5%

4%

a: The somnolence term includes somnolence, sedation, and hypersomnia.

b: The abdominal pain term includes abdominal pain, abdominal pain lower, abdominal pain upper, and abdominal tenderness

c: The hypotension term includes hypotension, diastolic hypotension, orthostatic hypotension, blood pressure decreased, blood pressure diastolic decreased, blood pressure systolic decreased).

d: The enuresis term includes enuresis, nocturia, and urinary incontinence.

Table 7: Adverse Reactions Leading to Discontinuation (≥ 2% for all doses of Guanfacine and > rate than in placebo) in Monotherapy Flexible Dose Study 4

GUANFACINE

Adverse Reaction Term

Placebo

(N = 112)

AM

(N = 107)

PM

(N = 114)

All Doses of Guanfacine (N = 221)

n (%)

n (%)

n (%)

n (%)

Total patients

0 (0%)

8 (7%)

7 (6%)

15 (7%)

Somnolencea

0 (0%)

4 (4%)

3 (3%)

7 (3%)

Adverse reactions leading to discontinuation in ≥ 2% in any dose group but did not meet this criteria in all doses combined: fatigue

a: The somnolence term includes somnolence, sedation, and hypersomnia.

Table 8: Other Common Adverse Reactions (≥ 2% for all doses of Guanfacine and > rate than in placebo) in the Monotherapy Flexible Dose Study 4

GUANFACINE

Adverse Reaction Term

Placebo

(N = 112)

AM

(N = 107)

PM

(N = 114)

All Doses of Guanfacine (N = 221)

Headache

11%

18%

16%

17%

Insomniaa

6%

8%

6%

7%

Diarrhea

4%

4%

6%

5%

Lethargy

0%

4%

3%

3%

Constipation

2%

2%

4%

3%

Dry Mouth

1%

3%

3%

3%

Adverse reactions ≥ 2% for all doses of guanfacine and > rate in placebo in any dose group but did not meet this criteria in all doses combined: affect lability (affect lability, mood swings), increased weight, syncope/loss of consciousness (loss of consciousness, presyncope, syncope), dyspepsia, tachycardia (tachycardia, sinus tachycardia), and bradycardia (bradycardia, sinus bradycardia).

a: The insomnia term includes insomnia, initial insomnia, middle insomnia, terminal insomnia, and sleep disorder.

Table 9: Percentage of Patients Experiencing Most Common (≥ 5% and at least twice the rate for placebo) Adverse Reactions in the Monotherapy Flexible Dose Study 5

Adverse Reaction Term

Placebo (N = 155)

All Doses of Guanfacine (N = 157)

Somnolencea

23%

54%

Insomniab

6%

13%

Hypotensionc

3%

9%

Dry Mouth

0%

8%

Postural Dizziness

2%

5%

Bradycardiad

0%

5%

a: The somnolence term includes somnolence, sedation, and hypersomnia.

b: The insomnia term includes insomnia, initial insomnia, middle insomnia, terminal insomnia, and sleep disorder.

c: The hypotension term includes hypotension, diastolic hypotension, orthostatic hypotension, blood pressure decreased, blood pressure diastolic decreased, blood pressure systolic decreased).

d: The bradycardia term includes bradycardia and sinus bradycardia.

There were no specific adverse reactions ≥2% in any treatment group that led to discontinuation in the monotherapy flexible dose study (Study 5).

Table 10: Other Common Adverse Reactions (≥2% for all doses of guanfacine and > rate than in placebo) in the Monotherapy Flexible Dose Study 5

Guanfacine

Adverse Reaction Term

Placebo (N = 155)

All Doses of Guanfacine (N = 157)

Headache

18%

27%

Fatigue

12%

22%

Dizziness

10%

16%

Decreased Appetite

14%

15%

Abdominal Paina

8%

12%

Irritability

4%

7%

Anxietyb

3%

5%

Rashc

1%

3%

Constipation

0%

3%

Increased Weight

2%

3%

Abdominal/Stomach Discomfortd

1%

2%

Pruritus

1%

2%

Adverse reactions ≥2% for all doses of guanfacine and >rate in placebo in any dose group but did not meet this criteria in all doses combined: nausea, diarrhea, vomiting, and depression (depressed mood, depression, depressive symptom).

a: The abdominal pain term includes abdominal pain, abdominal pain lower, abdominal pain upper, and abdominal tenderness.

b: The anxiety term includes anxiety and nervousness.

c: The rash term includes rash, rash generalized, and rash papular.

d: The abdominal/stomach discomfort term includes abdominal discomfort, epigastric discomfort, and stomach discomfort.

Adjunctive Trial

Table 11: Percentage of Patients Experiencing Most Common (≥ 5% and at least twice the rate for placebo) Adverse Reactions in the Short-Term Adjunctive Study 3

GUANFACINE + stimulant

Adverse Reaction Term

Placebo+ stimulant

(N = 153)

AM

(N = 150)

PM

(N = 152)

All Doses (N = 302)

Somnolencea

7%

18%

18%

18%

Insomniab

6%

10%

14%

12%

Abdominal Painc

3%

8%

12%

10%

Fatigue

3%

12%

7%

10%

Dizziness

4%

10%

5%

8%

Decreased Appetite

4%

7%

8%

7%

Nausea

3%

3%

7%

5%

a: The somnolence term includes somnolence, sedation, and hypersomnia.

b: The insomnia term includes insomnia, initial insomnia, middle insomnia, terminal insomnia, and sleep disorder.

c: The abdominal pain term includes abdominal pain, abdominal pain lower, abdominal pain upper, and abdominal tenderness.

There were no specific adverse reactions ≥ 2% in any treatment group that led to discontinuation in the short-term adjunctive study (Study 3).

Table 12: Other Common Adverse Reactions (≥ 2% for all doses of Guanfacine and > rate than in placebo) in the Short-Term Adjunctive Study 3

GUANFACINE + stimulant

Adverse Reaction Term

Placebo

(N = 153)

AM

(N = 150)

PM

(N = 152)

All Doses of Guanfacine

(N = 302)

Headache

13%

21%

21%

21%

Diarrhea

1%

4%

3%

4%

Hypotensiona

0%

4%

2%

3%

Constipation

0%

2%

3%

2%

Affect Labilityb

1%

3%

2%

2%

Dry Mouth

0%

1%

3%

2%

Bradycardiac

0%

1%

3%

2%

Postural Dizziness

0%

1%

3%

2%

Rashd

1%

1%

2%

2%

Nightmaree

1%

2%

1%

2%

Tachycardiaf

1%

2%

1%

2%

Adverse reactions ≥ 2% for all doses of guanfacineand > rate in placebo in any dose group but did not meet this criteria in all doses combined: irritability, vomiting, asthma (asthma, bronchospasm, wheezing), and enuresis (enuresis, nocturia, urinary incontinence).

a: The hypotension term includes hypotension, diastolic hypotension, orthostatic hypotension, blood pressure decreased, blood pressure diastolic decreased, blood pressure systolic decreased.

b: The affect lability term includes affect lability and mood swings.

c: The bradycardia term includes bradycardia and sinus bradycardia.

d: The rash term includes rash, rash generalized, and rash papular.

e: The nightmare term includes abnormal dreams, nightmare, and sleep terror.

f: The tachycardia term includes tachycardia and sinus tachycardia.

Effects on Blood Pressure and Heart Rate

In the monotherapy pediatric, short-term, controlled trials (Studies 1 and 2), the maximum mean changes from baseline in seated systolic blood pressure, diastolic blood pressure, and pulse were −5.4 mmHg, −3.4 mmHg, and −5.5 bpm, respectively, for all doses combined (generally one week after reaching target doses). For the respective fixed doses 1 mg/day, 2 mg/day, 3 mg/day or 4 mg/day the maximum mean changes in seated systolic blood pressure were -4.3 mmHg, -5.5 mmHg, -5.4 mmHg and -8.2 mmHg. For these respective fixed doses the maximum mean changes in seated diastolic blood pressure were -3.4 mmHg, -3.3 mmHg, -4.4 mmHg and -5.4 mmHg. For these respective fixed doses the maximum mean changes in seated pulse were -4.8 bpm, -3.1 bpm, -6.5 bpm and -8.6 bpm. Decreases in blood pressure and heart rate were usually modest and asymptomatic; however, hypotension and bradycardia can occur. Hypotension was reported as an adverse reaction for 7% of the guanfacine group and 3% of the placebo group. This includes orthostatic hypotension, which was reported for 1% of the guanfacine group and none in the placebo group. These findings were generally similar in the monotherapy flexible dose trials (Studies 4 and 5). In the adjunctive trial, hypotension (3%) and bradycardia (2%) were observed in patients treated with guanfacine as compared to none in the placebo group. In long-term, open-label studies, (mean exposure of approximately 10 months), maximum decreases in systolic and diastolic blood pressure occurred in the first month of therapy. Decreases were less pronounced over time. Syncope occurred in 1% of pediatric patients in the clinical program. The majority of these cases occurred in the long-term, open-label studies.

Discontinuation of Treatment

Blood pressure and pulse may increase above baseline values following discontinuation of guanfacine. In five studies of children and adolescents [see Clinical Studies (14)] , increases in mean systolic and diastolic blood pressure averaging approximately 3 mmHg and increases in heart rate averaging 5 beats per minute above original baseline were observed upon discontinuation with tapering of guanfacine. In a maintenance of efficacy study, increases in blood pressure and heart rate above baseline slowly diminished over the follow up period, which ranged between 3 and 26 weeks post final dose; the estimated average time to return to baseline was between six and twelve months. In this study, the increases in blood pressure and pulse were not considered serious or associated with adverse events. However, individuals may have larger increases than reflected by the mean changes.

In postmarketing experience, following abrupt discontinuation of guanfacine, rebound hypertension and hypertensive encephalopathy have been reported [see Warnings and Precautions (5.4) and Adverse Reactions (6.2)].

Effects on Height, Weight, and Body Mass Index (BMI)

Patients taking guanfacine demonstrated similar growth compared to normative data. Patients taking guanfacine had a mean increase in weight of 0.5 kg compared to those receiving placebo over a comparable treatment period. Patients receiving guanfacine for at least 12 months in open-label studies gained an average of 8 kg in weight and 8 cm (3 in) in height. The height, weight, and BMI percentile remained stable in patients at 12 months in the long-term studies compared to when they began receiving guanfacine.

Other Adverse Reactions Observed in Clinical Studies

Table 13 includes additional adverse reactions observed in short-term, placebo-controlled and long-term, open-label clinical studies not included elsewhere in section 6.1, listed by organ system.

Table 13: Other adverse reactions observed in clinical studies

Body System

Adverse Reaction

Cardiac

Atrioventricular block

General

Asthenia, chest pain

Immune System Disorders

Hypersensitivity

Investigations

Increased alanine amino transferase

Nervous system

Convulsion

Renal

Increased urinary frequency

Vascular

Hypertension, pallor

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