The question concerns a 35-year-old man with Klinefelter syndrome and who had surgery for hyperpara

Fråga: The question concerns a 35-year-old man with Klinefelter syndrome and who had surgery for hyperparathyroidism a few years ago. Over the last few months, he has been treated with omeprazole 2x 20 mg daily because of stomach complaints. During the last month, he has experienced muscle pain, especially in his shoulders and neck, paresthesiae in his fingers and toes and tiredness. In spite of discontinuation of the drug one month ago, the symptoms have not resolved. He is not suspected of having polyneuropathy. Could this be a side-effect of omeprazole?

Sammanfattning: Paresthesia and myalgia have been reported as uncommon side-effects occurring with omeprazole therapy. Further information is scarce, with only a few published case reports available. Symptoms seem to occur within a few days or weeks after the treatment is started and usually to resolve after discontinuation of the drug. The mechanism has so far not been elucidated. In conclusion, it could be possible that the symptoms in the present case might be due to the omeprazole therapy.

Svar: Paresthesia is mentioned in FASS (1) as one of the uncommon side-effects of omeprazole. However, hardly any reports could be found in the literature.

One case report (2) describes a peripheral neuropathy, possibly caused by omeprazole, in a 73-year-old woman. The patient was treated with 20 mg daily for three months and developed numbness and paresthesiae in her lower limbs. Ankle jerks were absent. After discontinuation of the drug, the symptoms disappeared within 10 days.

Another case report (3) concerns a subacute myopathy in a 78-year-old woman receiving treatment with omeprazole 20-40 mg daily. After four weeks, she developed a slowly progressive weakness in the neck and proximal limb muscles, which resolved after discontinuation of the drug. When she was rechallenged with omeprazole, the muscle weakness appeared again after two weeks, in combination with abnormally elevated muscle enzymes. Both weakness and enzyme abnormalities resolved within 30 days after withdrawal of the drug. According to the manufacturer (4), it appeared from clinical studies that paresthesia develops in about 0.1 per cent and myalgia in about 0.2 per cent of patients treated with omeprazole. The mechanism is not known. So far, the manufacturer has received 60 reports of paresthesia and, in five of these cases, the symptoms had not resolved after discontinuation of the drug, at least not within 7-14 days, when the cases were reported.

The Swedish Adverse Drug Reactions Advisory Committee has received 14 reports of myalgia and/or arthralgia and four reports of paresthesia possibly caused by omeprazole. The wide variety of symptoms described usually occurred within a few days after treatment with omeprazole was started and disappeared after discontinuation. However, detailed information concerning the clinical outcome was not available in several reports. Sixty-three reports of paresthesia in connection with omeprazole have been received by the WHO. It is difficult to judge these reports, since they do not provide with any detailed information.

We recommend that the present case to be reported to SADRAC. 1 FASS 1993; page 568 2 Sellapah S: An unusual side effect of omeprazole: case report. Br J Gen Pract 1990; 40: 389 3 Garrote FJ, Lacambra C, del Ser T, Garcia Diaz B, Obeso G, Solis J: Subacute myopathy during omeprazole therapy. Lancet 1992; 340: 672 4 Personal communication, Vera Nilsson, Astra Hässle AB