Open-label study of hemin for acute porphyria: clinical practice implications.

BACKGROUND: The acute porphyrias are rare inherited diseases characterized by acute episodes of life-threatening symptoms. Hemin was approved for treating these disorders in 1983. This open-label study of hemin therapy, conducted to demonstrate the safety of hemin manufactured in a new facility, is the largest to date and provides an overview of the use of hemin in clinical practice in the United States.
METHODS: During 8 months when hemin was available only through study participation, 130 patients with a clinical diagnosis of acute porphyria received hemin as regularly prescribed by their doctor. Laboratory information and data on use of hemin for acute and prophylactic treatment were analyzed from case report forms.
RESULTS: Hemin was administered to 111 patients for treatment of 305 acute attacks and to 40 patients for prophylaxis (usually by weekly or biweekly infusions). Diagnostic laboratory findings reported for 69 patients were confirmatory in only 26. Hemin was regarded as effective for all attacks in 73% of patients. Doses for acute attacks were less than the recommended 3-4 mg/kg/day in 20% of patients. Among 31 patients who received hemin prophylaxis for >1 month, 68% did not require subsequent hemin treatment for acute attacks. Most adverse events were attributed to porphyria and not treatment, and were more common in patients treated for acute attacks rather than prophylaxis.
CONCLUSIONS: Safety and perceived efficacy of hemin were consistent with previous studies. Physician education is needed regarding use of diagnostic tests and recommended dosing. Preventive regimens are common and deserve further study.