|Systematic (IUPAC) name|
|Biological half-life||6 hours|
|ATC code||P01BA03 (WHO)|
|Molar mass||259.347 g/mol[[Script error: No such module "String".]]|
Primaquine (or primaquine phosphate) is a medication used in the treatment of malaria and Pneumocystis pneumonia. It is a member of the 8-aminoquinoline group of drugs that includes tafenoquine and pamaquine.
Primaquine is mainly used to treat the P. vivax or P. ovale malaria. Once the parasite has been eliminated from the bloodstream, the remaining hypnozoites must be removed from the liver and this is done by administering a 14 day course of primaquine. This process is called a radical cure.
If primaquine is not administered to patients with proven P. vivax or P. ovale infection, there is a very high likelihood of relapse within weeks or months (sometimes years).
When attempting a radical cure, primaquine requires the presence of quinine or chloroquine in order to work. If primaquine is given alone, the cure rate is only 21%. It is not known if other antimalarials such as mefloquine are likewise able to potentiate the effect of primaquine.
Primaquine is not routinely used to prevent malaria in travelers, and is only used as such when no other alternatives are appropriate. Primaquine is the recommended prophylactic agent by the Centers for Disease Control and Prevention (CDC) in some instances.
Primaquine is also sometimes used presumptively to prevent malaria in people who have gone to areas where P. vivax or P. ovale are endemic (called terminal prophylaxis), but this controversial practice is not common outside of the U.S.
Primaquine is also used in the treatment of Pneumocystis pneumonia (PCP), a fungal infection commonly occurring in people with AIDS and, more rarely, in those taking immunosuppressive drugs. To treat PCP effectively it is usually combined with clindamycin.
Side effects of primaquine administration include nausea, vomiting and stomach cramps. Other known adverse effects that occasionally occur are headache, visual disturbances and intense itching. Primaquine has also been shown to cause hemolytic anemia in people of African or Mediterranean descent; this was a plot point in the M*A*S*H episode "The Red/White Blues", in which Lebanese-American Max Klinger and Jewish-American Orderly Goldman developed anemia while taking primaquine, confusing the doctors who thought it was only a possibility if he were of African descent.
Primaquine causes methemoglobinemia in all patients who take it (levels of up to 18% are reported, normal level is <1%), but this seldom causes symptoms and is always self-limiting. Dangerous levels of methemoglobinemia only occur in patients with glucose-6-phosphate dehydrogenase deficiency.
Primaquine should not be administered to anyone with glucose-6-phosphate dehydrogenase deficiency because there can be a severe reaction with hemolytic anemia. Primaquine is contraindicated in pregnancy, because the Glucose-6-phosphate dehydrogenase status of the fetus would be unknown. Primaquine should not be given to patients with NADH methemoglobin reductase deficiency.
Primaquine doses are always expressed as base, not as salt (15 mg base=26.3 mg phosphate salt).
- Plasmodium vivax: 30 mg once daily for 14 days (note that older authorities quote 15 mg instead);
- Plasmodium ovale: 15 mg once daily for 14 days.
The FDA licensed dose in the U.S. is 15 mg once daily, but this is not the dose recommended by the CDC for P. vivax; the FDA decision in 1952 to limit the primaquine dose to 15 mg was motivated by the fact that G-6-PD testing was not routinely available, 15 mg was known to be effective against the P. vivax strains found in Korea (in the US, the main use of primaquine at that time was to treat soldiers returning from war), and because 15 mg of primaquine is not likely to cause hemolysis in G-6-PD deficient patients. Primaquine is not licensed in the UK, but is available on a named-patient basis.
The dose of primaquine in primary malaria prophylaxis is 30 mg once daily, starting the day before travel and continuing for 7 days after returning. It needs only to be given for seven days after returning because primaquine is active against liver schizonts (the exoerythrocytic stages) and is therefore a causal prophylactic. In children, the dose is 0.6 mg/kg/day (the maximum daily dose is 30 mg).
Manufacturing and availability
Primaquine was first tested on humans during the Stateville Penitentiary Malaria Study in 1944. Primaquine was licensed for use in the USA by the FDA in 1952 and is available as a generic drug from a variety of manufacturers.
Primaquine is not licensed for use in the United Kingdom. It is available on a named patient basis only from certain pharmaceutical providers. Primaquine tablets available in the UK contain 7.5 mg primaquine base (13.2 mg phosphate salt). Primaquine tablets available in the U.S. contain 15 mg base (26.3 mg phosphate salt).
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- Mihaly GW, Ward SA, Edwards G; et al. (1985). "Pharmacokinetics of primaquine in man. I. studies of the absolute bioavailability and effects of dose size". Br J Clin Pharmacol. 19 (6): 745–50. PMC . PMID 4027117.
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- Alving AS, Arnold J, Hockwald RS; et al. (1955). "Potentiation of the curative action of primaquine in vivax malaria by quinine and chloroquine". J Lab Clin Med. 46 (2): 301–6. PMID 13242948.
- Hill DR, Baird JK, Parise ME; et al. (2006). "Primaquine: Report from CDC expert meeting on malaria chemoprophylaxis I". Am J Trop Med Hyg. 75 (3): 402–15. PMID 16968913.
- Health Information for Travelers to Argentina, Centers for Disease Control and Prevention
- Clayman CB, Arnold J, Hockwold RS; et al. (1952). "Toxicity of primaquine in caucasians". JAMA. 149: 1563–68.
- Cohen RJ, Sachs JR, Wicker DJ, Conrad ME. (1968). "Methemoglobinemia provoked by malarial chemoprophylaxis in Vietnam". N Engl J Med. 279 (21): 1127–31. doi:10.1056/NEJM196811212792102. PMID 5686480.
- Coleman MD, Coleman NA. (1996). "Drug-induced methaemoglobinaemia. Treatment issues". Drug Saf. 14 (6): 394–405. doi:10.2165/00002018-199614060-00005. PMID 8828017.
- Baird JK, Hoffman SL. (2004). "Primaquine therapy for malaria". Clin Infect Dis. 39 (9): 1336–45. doi:10.1086/424663. PMID 15494911.