Pregabalin induced balance disorder, asthenia, edema, and constipation in an elderly adult: A case report.

Background: Pregabalin is widely used to treat neuropathic pain associated with postherpetic neuralgia. To our knowledge, this is the first report on simultaneously occurring dose-related adverse drug reactions (ADRs) of balance disorder, asthenia, peripheral edema, and constipation in an elderly patient after pregabalin.

Case Summary: A 76-year-old female with a history of postherpetic neuralgia was prescribed pregabalin (300 mg daily). After taking pregabalin for 7 d, the patient developed balance disorder, weakness, peripheral pitting edema (2+), and constipation. On days 8-14, the pregabalin dose was reduced to 150 mg/d based on creatinine clearance. The patient's peripheral edema improved significantly with the disappearance of all other adverse symptoms. On day 15, the pregabalin dose was increased to 225 mg/d to relieve pain. Unfortunately, the symptoms mentioned earlier gradually reappeared after 1 wk of pregabalin treatment. However, the complaints were not as severe as when taking 300 mg/d pregabalin. The patient consulted her pharmacist by telephone and was advised to reduce the dose of pregabalin to 150 mg/d and add acetaminophen (0.5 g, q6h) to relieve pain. The patient's ADRs gradually improved over the following week.

Conclusion: Older patients should be prescribed a lower initial dose of pregabalin. The dose should be titrated to the maximum tolerable dose to avoid dose-limiting ADR. Dose reduction and the addition of acetaminophen may help limit ADR and improve pain control.