Medication	Dosage
Topical agents
Capsaicin cream (Zostrix)	Apply to affected area three to five times daily.
Lidocaine (Xylocaine) patch	Apply to affected area every 4 to 12 hours as needed.
Tricyclic antidepressants
Amitriptyline (Elavil)	10 to 25 mg orally at bedtime; increase dosage by 25 mg every 2 to 4 weeks until response is adequate, or to maximum dosage of 150 mg per day.
Nortriptyline (Pamelor)	10 to 25 mg orally at bedtime; increase dosage by 25 mg every 2 to 4 weeks until response is adequate, or to maximum dosage of 125 mg per day.
Imipramine (Tofranil)	25 mg orally at bedtime; increase dosage by 25 mg every 2 to 4 weeks until response is adequate, or to maximum dosage of 150 mg per day.
Desipramine (Norpramin)	25 mg orally at bedtime; increase dosage by 25 mg every 2 to 4 weeks until response is adequate, or to maximum dosage of 150 mg per day.
Anticonvulsants
Phenytoin (Dilantin)	100 to 300 mg orally at bedtime; increase dosage until response is adequate or blood drug level is 10 to 20 μg per mL (40 to 80 μmol per L).
Carbamazepine (Tegretol)	100 mg orally at bedtime; increase dosage by 100 mg every 3 days until dosage is 200 mg three times daily, response is adequate or blood drug level is 6 to12 μg per mL (25.4 to 50.8 μmol per L).
Gabapentin (Neurontin)	100 to 300 mg orally at bedtime; increase dosage by 100 to 300 mg every 3 days until dosage is 300 to 900 mg three times daily or response is adequate. (Drug levels for clinical use are not available.)