Interaction : Riamet and Akurit 4

Availability in Hospital Keningau:

• Riamet (Artemether 20mg + Lumenfantrine 120mg)
• Akurit-4 (Rifampicin 150mg, Isoniazid 75mg, Pyrazinamide 400mg & Ethambutol HCl 275mg)

Interaction:

• Oral administration of Rifampicin (600mg) daily, a strong CYP3A4 inducer with Riamet Tablets (6 dose regimen over 3 days) in 6 HIV-1 and Tuberculosis co-infected adults without Malaria resulted in significant decreases in Arthemeter (89%) ,DHA (85%) and Lumenfantrine (68%) when compared to exposure values after Riamet alone.
• Concomitant use of strong inducers such as Rifampicin, Carbamazepine, Phenytoin, St John’s Wart is contraindicated with Riamet.

Alternatives:

• A study was done on the effect of combined therapy (rifampicin and quinine) in patients with acute uncomplicated P.Falciparum Malaria. Interestingly, they observed that the parasite clearance was faster with the combination.
• This could be because of the rifampicin antimalarial effect rather than a drug interaction as rifampicin can take several days to induce CYP3A4 activity that is responsible for quinine metabolism.
• After the second day of rifampicin treatment, quinine pre-dose plasma concentrations decreased progressively throughout the treatment period, leading to a fall in quinine activity that may have been the reason for a malaria recrudescence rate five times higher in this group.
• In those patients who are already on rifampicin for the treatment of TB, quinine doses must be increased.

*Quninie Sulphate 300mg is available in Hospital Keningau

References:

1. Riamet ® Product leaflet
2. Mims Malaysia
3. Sousa, M., Pozniak, A., & Boffito, M. (2008). Pharmacokinetics and pharmacodynamics of drug interactions involving rifampicin, rifabutin and antimalarial drugs. Journal of Antimicrobial Chemotherapy, 62(5), 872-878.