A 22-year-old male patient had been treated with Paraflex Comp (chlorzoxazone 125 mg, acetylsalicyl

Fråga: A 22-year-old male patient had been treated with Paraflex Comp (chlorzoxazone 125 mg, acetylsalicylic acid 500 mg, dextropropoxyphene napsylas 45 mg) 5-6 tablets per day for four weeks because of back pain. After 2.5 weeks of treatment, the patient began experiencing symptoms such as stomach pain, vomiting, a decrease in body weight of 5-6 kg, pain in all of his joints and fever. Paraflex Comp was stopped on September 9 and he was admitted to hospital. His liver function values were: ALAT 10, ASAT 1.5, ALP 5.0. The liver values were improved 3 days later (12/9): ALAT 6, ASAT 0.7. The patient also had haematuria. The patient was not taking any other drugs. Could this patient´s symptoms be caused by Paraflex Comp?

Sammanfattning: Nausea, vomiting and discomfort in the stomach are common side-effects of chlorzoxazone and dextropropoxyphen treatment. Reversible liver damage in relation to the treatment has also been well documented. The liver symptoms usually appear within 1-5 weeks after beginning the drug treatment and disappear rapidly when the treatment is discontinued. Fever and haematuria have been reported but seem to be rare. No documentation has been found concerning joint pain caused by the treatment.

Svar: The most common side-effects of chlorzoxazone are drowsiness, dizziness, nausea, vomiting and abdominal discomfort (1).

Liver damage caused by chlorzoxazone-dextropropoxyphen combination has been documented and discussed (2). The first case reported to the Swedish Adverse Drug Reactions Advisory Committee (SADRAC) concerning liver damage and treatment with this combination was in 1970. Through 1982, there were 13 reports for the combination and 10 reports for other preparations containing dextropropoxyphen or chlorzoxazone. Since liver injury has been documented for both drugs independently (2,3) an additive effect of the two drugs can not be excluded. The symptoms of the liver side-effects usually appear within 1-5 weeks after starting the treatment. In most cases, there was a marked increase of alkaline phosphatase together with a slight or pronounced increase of transaminases. Icterus occurred in many cases. Symptoms usually disappeared rapidly after discontinuation of the treatment and liver values normalized within a few weeks. Since eczema sometimes appeared together with the liver damage, and re-exposure to the drug again caused increased liver values, a mechanism of hypersensitivity has been suspected (2).

Among the reports to SADRAC, there have been 29 cases of liver side-effects, three cases of fever, 17 cases of gastrointestinal side-effects and one case of haematuria, where the connections between Paraflex Comp treatment and the side-effects have been judged possible, probable or not excluded. There are no reports of pain in the joints in relation to the treatment.

We recommend that this case be reported to SADRAC.