Table 1.

Anti-myotonic drugs used to treat symptoms of NDM [64]

Anti-myotonic drugs	Dosage	Side effects	Monitoring
Mexiletine [65]	Start 150 mg BID with slow titration to 200–300 mg TID	GI distress, tremor, ataxia	LFTs, EKG
Ranolazine [66]	500–1000 mg BID	GI distress, dizziness, headache, prolonged QT interval, vasovagal syncope	Renal function periodically with creatinine clearance < 60 mL/min
Quinine [67]	200–1200 mg/day	Cardiac arrhythmias, hypersensitivity reactions, bone marrow suppression, liver damage, GI distress, visual disturbance	CBC with platelet count, LFTs, blood glucose, EKG, ophthalmologic evaluation
Procainamide [67, 68]	125–1000 mg/day	Rash, GI distress, positive ANA	EKG, creatinine, CBC, ANA
Phenytoin [67, 68]	300–400 mg/day	Gingival hypertrophy, agranulocytosis, pancytopenia, rash, cognitive impairment, liver damage	CBC, LFTs
Flecainide [69]	Start 100 mg/day, titrate to 100 mg BID	Cardiac arrhythmias, dizziness, rash	EKG, periodic drug serum concentrations
Carbamazepine [70]	20 mg/kg divided TID	Rash, agranulocytosis, pancytopenia, liver damage	LFTs, CBC, TSH
Acetazolamide [67, 71]	125 mg BID with slow titration to goal dose 250 mg TID	GI distress, electrolyte abnormalities (hypokalemia, hyponatremia), paresthesias, nephrolithiasis, rash, agranulocytosis	Serum electrolytes, LFTs, CBC
Lamotrigine [72, 73]	Start at 25 mg qday and titrate slowly to 300 mg qday	Headache, fatigue, and skin rash	LFTs, renal function as hepatic and renal impairment will drive dose reduction

ANA = antinuclear antibodies; BID = twice a day; CBC = complete blood count; GI = gastrointestinal; LFTs = liver function tests; NA = not applicable; TID = 3 times a day; TSH = thyroid-stimulating hormone