Cardura (doxazosin) had its fair share of side effects even before three doctors in England discovered another possible reaction that has never been recorded in any drugs reference work.
Cardura, produced by Pfizer, has been licensed for use in the UK and the US to treat hypertension (high blood pressure) and prostate problems.
Well documented reactions include fatigue, headache and dizziness, but apart from some instances of anxiety and insomnia, few cases of psychiatric disorders have been reported.
But doctors at the Wirral Hospital on Merseyside write in the British Medical Journal (BMJ 1997; 314: 1869) about a case of acute psychosis suffered by a 71 year old woman while she was taking the drug.
She had to be admitted to the hospital’s psychogeriatric ward after she began hearing noises coming from the walls of her house. This changed to hearing violent videos being played all night, and she had even called the police and environmental health officers to complain. She also heard her neighbours discussing her in a threatening manner. In the last 24 hours before she was admitted to hospital, she said she heard boxes being dragged across the floor of her bedroom and her son, who lives in America, being tortured.
Her psychosis started within a week or so of her doxazosin dosage being increased from 8 mg to 16 mg a day. The psychosis reduced when the dose was adjusted back to 8 mg.
More common reactions to the drug include pains through the body, hypotension (low blood pressure), palpitations, abdominal pain, diarrhea, edema (fluid building up in the tissues), sleepiness, respiratory disorder, urinary tract infection and increased sweating.
The doctors have reported the psychosis reaction to the Committee on Safety of Medicines, although currently only 4 per cent of effects from the drug are psychiatric symptoms.