Intuniv (Guanfacine Extended Release) 2 MG: Administration Guidelines and Side Effects
Primary Indication and Dosing
Intuniv (guanfacine extended release) 2 mg is FDA-approved for ADHD treatment in children and adolescents aged 6-17 years, with a typical starting dose of 1 mg daily, titrated by 1 mg weekly based on response and tolerability to a target range of 0.05-0.12 mg/kg/day or 1-7 mg daily. 1
Administration Guidelines
Dosing Schedule
- Start at 1 mg once daily, typically given in the morning or evening based on tolerability 1, 2
- Titrate by 1 mg increments weekly to achieve optimal symptom control 1
- Maximum dose: 7 mg daily (or 0.12 mg/kg/day) 1
- The 2 mg tablet represents a mid-range therapeutic dose in the titration schedule 1
Administration Instructions
- Can be administered morning or evening - both timing strategies show equivalent efficacy 2
- Swallow tablets whole; do not crush, chew, or break extended-release formulation 3
- May be taken with or without food 4
Pharmacokinetic Considerations
- Half-life: 14-18 hours in children and adolescents, supporting once-daily dosing 4
- Linear pharmacokinetics - dose increases produce proportional increases in drug exposure 4
- Higher plasma concentrations in children versus adolescents due to body weight differences 4
Common Side Effects
Most Frequent Adverse Events
- Somnolence/sedation (most common, dose-dependent) 5, 3, 4
- Dry mouth (47-60% in adult studies) 5
- Fatigue/weakness 5
- Headache 5, 6
- Dizziness 5, 6
- Constipation (10-16%) 5
- Insomnia 5, 4
- Blurred vision 4
- Altered mood 4
Cardiovascular Effects
- Modest decreases in blood pressure and heart rate are common but typically not clinically significant 3, 2
- Mean small decreases in pulse, systolic, and diastolic blood pressure observed in clinical trials 2
- Orthostatic hypotension is uncommon compared to other alpha-2 agonists 7
- Bradycardia may occur 5
Serious Adverse Effects and Monitoring
Critical Safety Concerns
- Sedation is the most significant adverse effect, particularly at higher doses (4 mg) 3, 4
- Cardiovascular monitoring required: baseline and periodic blood pressure and heart rate measurements 1, 2
- ECG monitoring recommended in patients with cardiac risk factors 2
Rare but Serious Events
Spontaneously reported serious events (without definitive causality) include 5:
- Acute renal failure
- Cardiac fibrillation
- Cerebrovascular accident
- Congestive heart failure
- Heart block
- Myocardial infarction
Discontinuation Guidelines
Withdrawal Syndrome Prevention
Never abruptly discontinue guanfacine - taper gradually to avoid rebound hypertension and withdrawal symptoms. 8, 9, 5
- Rebound hypertension risk is lower than with clonidine but still present 5, 7
- Withdrawal symptoms typically occur 2-4 days after discontinuation (delayed compared to clonidine) 5
- Blood pressure usually returns to baseline within 2-4 days when tapered appropriately 5
- Symptoms are generally mild when they occur 7
Special Populations
Pregnancy and Lactation
- Pregnancy: Limited data available - one study in 30 preeclamptic patients showed no malformations, though 20% had low birth weight infants 1
- Could be considered after risk-benefit discussion, though alternative agents preferred 1
- Lactation: Caution advised - no published breastfeeding data available 1
- Monitor infants for drowsiness and hypotonia if used during breastfeeding 1, 9
Combination Therapy
- Safe to combine with psychostimulants (methylphenidate, amphetamines) for ADHD 6, 2
- No pharmacokinetic drug-drug interactions with methylphenidate extended release 6
- Adjunctive therapy shows significantly greater ADHD symptom improvement versus stimulant monotherapy 2
- No new safety signals emerge when combined with stimulants 2
Clinical Pearls and Pitfalls
Common Pitfalls to Avoid
- Do not use as first-line hypertension treatment in older adults - reserved as last-line due to significant CNS effects 8, 9
- Most adverse events are mild to moderate and highest frequency occurs at 4 mg doses 4
- Sedation typically improves over time with continued treatment 5
- Sexual dysfunction is uncommon compared to other centrally-acting agents 7
Monitoring Schedule
- Baseline: Blood pressure, heart rate, ECG (if cardiac risk factors) 2
- During titration: Vital signs at each dose increase 4
- Ongoing: Periodic cardiovascular monitoring 1, 2
- Laboratory evaluations: As clinically indicated 2