What are the side effects of Adalat XL (nifedipine)?

Side Effects of Adalat XL (Nifedipine)

The most common side effect of Adalat XL (nifedipine) is peripheral edema, which is dose-dependent and occurs in 18-29% of patients, followed by headache, flushing, dizziness, and potential reflex tachycardia due to its potent vasodilatory effects. 1

Common Side Effects

Nifedipine, a dihydropyridine calcium channel blocker, causes side effects primarily related to its vasodilatory action:

• Peripheral edema: Dose-related with frequency of 18% on 30 mg daily, 22% on 60 mg daily, and 29% on 90 mg daily 1
• Cardiovascular effects:
  • Headache (15% vs 10% on placebo)
  • Flushing (10% vs 3% on placebo)
  • Dizziness (10% vs 4% on placebo)
  • Palpitations and reflex tachycardia 2
• Gastrointestinal effects:
  • Nausea (4% vs 2% on placebo)
  • Constipation (reported in <3% of patients) 1

Less Common Side Effects

The following side effects occur with an incidence of 3% or less:

• Musculoskeletal: Leg cramps
• Respiratory: Epistaxis (nosebleeds), rhinitis
• Urogenital: Impotence, urinary frequency
• Dermatologic: Rash 1

Rare but Serious Side Effects

Rare adverse events reported with nifedipine include:

• Allergic reactions: Anaphylactic reaction, Stevens-Johnson syndrome, toxic epidermal necrolysis, urticaria
• Hepatic: Allergenic hepatitis, jaundice
• Hematologic: Anemia, leukopenia, thrombocytopenia
• Neurological: Syncope, transient blindness at peak plasma levels, tremor, paranoid syndrome 1

Precautions and Contraindications

Nifedipine should be used with caution or avoided in:

1. Patients with significantly impaired left ventricular function due to potential negative inotropic effects 3, 4
2. Patients with atrioventricular conduction abnormalities 4
3. Patients with heart failure with reduced ejection fraction 4

Drug Interactions

Important interactions to be aware of:

• Beta-blockers: Nifedipine should not be used without concomitant beta-blocker therapy in certain cardiac conditions, though caution is advised due to potential additive hypotensive effects 3, 4
• Digoxin: Nifedipine may increase serum digoxin levels, though the clinical significance is uncertain 4, 2
• Magnesium sulfate: Combination may increase risk of uncontrolled hypotension 4

Monitoring Recommendations

When taking Adalat XL, patients should be monitored for:

• Blood pressure: Check in both sitting and standing positions to detect orthostatic changes 4
• Peripheral edema: Particularly in elderly patients 4
• Cardiovascular status: Watch for signs of hypotension or tachycardia 2

Comparison with Other Calcium Channel Blockers

Nifedipine differs from non-dihydropyridine calcium channel blockers (verapamil, diltiazem) in its side effect profile:

• Nifedipine: More likely to cause vasodilatory symptoms (headache, flushing, peripheral edema) and reflex tachycardia; minimal effect on cardiac conduction 4, 2
• Verapamil/Diltiazem: More likely to cause conduction disturbances, bradycardia, and constipation; stronger negative inotropic effects 4, 2

Clinical Pearls

• Peripheral edema with nifedipine is dose-dependent and may be reduced by combining with ACE inhibitors 4
• The vasodilatory side effects (headache, flushing) often diminish with continued therapy 2
• When switching between different formulations of nifedipine (e.g., Adalat CC and Procardia XL), blood pressure, heart rate, and adverse effects should be monitored 2-4 weeks after the exchange 5