Oxamniquine

'Oxamniquine' is "an anthelmintic with schistosomicidal activity against Schistosoma mansoni, but not against other Schistosoma spp. Oxamniquine causes worms to shift from the mesenteric veins to the liver where the male worms are retained; the female worms return to the mesentery, but can no longer release eggs. (From Martidale, The Extra Pharmacopoeia, 31st ed, p121)" more...

History

In 1979, Pfizer at Sandwich was presented with the Queen’s Award for Technological Achievement in recognition of the outstanding contribution made to tropical medicine by MANSIL™ (oxamniquine).

Pharmacokinetics

Peak plasma concentrations are achieved 1 to 3 hours after a dose and the plasma half-life is 1 to 2.5 hours.

It is extensively metabolised to inactive metabolites, principally the 6-carboxy derivative, which are excreted in the urine. About 70% of a dose of oxamniquine is excreted as the 6-carboxy metabolite within 12 hours of a dose; traces of the 2-carboxy metabolite have also been detected in the urine.

Mode of Action

Is a semisynthetic tetrahydroquinoline and possibly acts by DNA binding resulting in contraction and paralysis of the worms and eventual detachment from terminal venules in the mesentry and death.

Uses

For treatment of schistomiasis. According to one systematic review it is equally effective as praziquantel (for treating S. mansoni).

Contraindications and Precautions

Pregnancy

Side Effects

It is generally well tolerated following oral doses. Dizziness with or without drowsiness occurs in at least a third of patients, beginning up to 3 hours after a dose and usually lasting for up to 6 hours. Headache and gastrointestinal effects such as nausea, vomiting, and diarrhoea are also common.

Allergic-type reactions including urticaria, pruritic skin rashes, and fever may occur. Liver enzyme values have been raised transiently in some patients. Epileptiform convulsions have been reported, especially in patients with a history of convulsive disorders. Hallucinations and excitement have occurred rarely.

A reddish discoloration of urine, probably due to a metabolite of oxamniquine, has been reported.

Dosage

Oral, 15 mg per kg of body weight two times a day for one day.

Brandnames

• Vansil; (Pfizer) 250 mg capsules, syrup 250 mg/5ml
• Mansil; 250 mg Tablets

External References

• AHFS Database

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