Drug use in porphyria: a therapeutic dilemma

Jose J, Saravu K, Shastry BA, Jimmy B
Correspondence: Mr Jimmy Jose, jimmy_jose2001@yahoo.com

ABSTRACT
One of the most frequent precipitating factors for attacks of porphyria is the administration of drugs. Use of drugs with porphyrinogenic potential often worsens the condition and often poses a therapeutic dilemma. A 23-year-old female patient presented to the casualty room with abdominal pain, chest pain and vomiting. Her past medical history was significant with episodes of generalised abdominal pain. The patient was initially treated for her abdominal pain and vomiting. She developed seizures and was treated with diazepam and phenytoin. Based on the positive investigation reports (positive urine porphyrins, elevated urine ALA and positive porphobilinogen) and symptoms, a diagnosis of acute intermittent porphyria (AIP) was done. Before the diagnosis of AIP was made, the patient was treated with drugs which are not considered to be safe in porphyric patients, such as phenytoin, metoclopramide, and diclofenac. The use of these drugs probably contributed to the initial worsening of the patient's clinical condition. After the diagnosis of AIP was made, the patient was treated with safer alternatives; gabapentin as the antiepileptic agent, promethazine as antiemetic, and propanalol as the antihypertensive agent. Withdrawal of the unsafe agents and symptomatic management with the safer alternatives contributed to the recovery of the patient. Along with the case report and the observations made on the various drugs used in the patient, the importance of the various information sources available on the safety potential of these agents is discussed. The observations with the drugs used in our case will be a useful addition to the existing information on the safety of these agents.

Keywords: acute intermittent porphyria, drug safety, porphyria
Singapore Med J 2008; 49(10): e272-e275