Pyritinol

General information

Pyritinol (pyridoxine disulfide or pyrithioxine) is a sulfhydryl-containing compound, a dimer of 5-thiopyridoxine. It was used from 1961 onwards as a psychostimulant of doubtful efficacy, but apparently without adverse reactions, and then largely abandoned. When it was re-introduced in some countries for rheumatoid arthritis, adverse reactions were registered in 25% of patients.

Cross-allergy with d -penicillamine has been hypothesized to explain the apparently higher frequency of adverse reactions to pyritinol in patients with rheumatoid arthritis [ ].

In usual doses, 600–800 mg/day, pyritinol has a profile of adverse reactions reminiscent of that of penicillamine [ , ]. Some 40% of users have adverse reactions, leading to withdrawal in about 23% of the total. The most common are non-specific rashes and stomatitis; in addition, pemphigus, lichen planus, and photosensitivity have occurred. Gastrointestinal symptoms (diarrhea, gastralgia, nausea, loss of taste) can occur, but are less frequent than with penicillamine. Thrombocytopenia, reversible extramembranous glomerulonephritis with nephrotic syndrome [ ], a myasthenia-like picture, and acute polymyositis with positive rechallenge have also been described [ ].

In a collaborative study of the French Pharmacovigilance Centers there were 23 reports of suspected reactions to pyritinol, including four cases of pemphigus, three of agranulocytosis (but other drugs taken were oxyphenbutazone or clomipramine), two of nephrosis, and two of a lupus-like syndrome [ ].

Drug studies