Acute intermittent porphyria (AIP) is a rare autosomal dominant condition caused by a defect in porphobilinogen deaminase, an enzyme involved in the biosynthesis of haem. The results in the toxic accumulation of delta aminolaevulinic acid and porphobilinogen. It characteristically presents with abdominal and neuropsychiatric symptoms in 20-40-year-olds. AIP is more common in females (5:1)

Common Drug Causes

Drugs are important causes of acute attacks of intermittent porphyria. More commonly noted drugs include:

• Antibiotics
  • Cephalosporins
  • Macrolides
  • Tetracycline
  • Trimethoprim
  • Sulphonamides
  • Chloramphenicol
  • Metronidazole
  • Rifampicin
  • Nitrofurantoin
• Alcohol
• Hormonal contraceptives
• Tricyclic antidepressants
• Anaesthetic agents
• Benzodiazepines
• Statins
• ACE-Is

PC

The classical presentation is a combination of abdominal, neurological and psychiatric symptoms:

• abdominal: abdominal pain, vomiting
• neurological: motor neuropathy
• psychiatric: e.g. depression
• hypertension and tachycardia common