Pamaquine is an

8-aminoquinoline 8-Aminoquinoline is the 8-amino derivative of quinoline. Often abbreviated AQ, it is a pale yellow solid. It is structurally analogous to 8-hydroxyquinoline. Drug derivatives The derivatives primaquine, tafenoquine and pamaquine have been t ...

drug formerly used for the treatment of

malaria Malaria is a mosquito-borne infectious disease that affects humans and other animals. Malaria causes symptoms that typically include fever, tiredness, vomiting, and headaches. In severe cases, it can cause jaundice, seizures, coma, or deat ...

. It is closely related to

primaquine Primaquine is a medication used to treat and prevent malaria and to treat ''Pneumocystis'' pneumonia. Specifically it is used for malaria due to ''Plasmodium vivax'' and ''Plasmodium ovale'' along with other medications and for prevention if othe ...

Synonyms

*Plasmochin *Plasmoquine *Plasmaquine

Uses

Pamaquine is effective against the hypnozoites of the relapsing malarias (''

P. vivax ''Plasmodium vivax'' is a protozoal parasite and a human pathogen. This parasite is the most frequent and widely distributed cause of recurring malaria. Although it is less virulent than ''Plasmodium falciparum'', the deadliest of the five human ...

'' and ''

P. ovale ''Plasmodium ovale'' is a species of parasitic protozoon that causes tertian malaria in humans. It is one of several species of ''Plasmodium'' parasites that infect humans, including ''Plasmodium falciparum'' and ''Plasmodium vivax'' which are ...

''); and unlike primaquine, it is also very effective against the erythrocytic stages of all four human malarias. One small clinical trial of pamaquine as a causal

prophylactic Preventive healthcare, or prophylaxis, consists of measures taken for the purposes of disease prevention.Hugh R. Leavell and E. Gurney Clark as "the science and art of preventing disease, prolonging life, and promoting physical and mental hea ...

was disappointing (whereas primaquine is an extremely effective causal prophylactic). Pamaquine is more toxic and less efficacious than

; therefore, pamaquine is no longer routinely used, and of the two, only primaquine is currently recommended by the

World Health Organization The World Health Organization (WHO) is a specialized agency of the United Nations responsible for international public health. The WHO Constitution states its main objective as "the attainment by all peoples of the highest possible level o ...

Adverse effects

Like primaquine, pamaquine causes

haemolytic anaemia Hemolytic anemia or haemolytic anaemia is a form of anemia due to hemolysis, the abnormal breakdown of red blood cells (RBCs), either in the blood vessels (intravascular hemolysis) or elsewhere in the human body (extravascular). This most common ...

in patients with

G6PD deficiency Glucose-6-phosphate dehydrogenase deficiency (G6PDD), which is the most common enzyme deficiency worldwide, is an inborn error of metabolism that predisposes to red blood cell breakdown. Most of the time, those who are affected have no symptoms. ...

. Patients should therefore always be screened for G6PD deficiency prior to being prescribed pamaquine.

History

Pamaquine was the second synthetic antimalarial drug to be discovered (after

methylene blue Methylthioninium chloride, commonly called methylene blue, is a salt used as a dye and as a medication. Methylene blue is a thiazine dye. As a medication, it is mainly used to treat methemoglobinemia by converting the ferric iron in hemoglob ...

). It was synthesised by Schulemann, Schoenhoeffer and Wingler in 1924. In 1926, Roehl demonstrated that pamaquine was effective in treating malaria in birds, and introduced it into use in humans. Its development is of interest in the history of

pharmacotherapy Pharmacotherapy is therapy using pharmaceutical drugs, as distinguished from therapy using surgery (surgical therapy), radiation (radiation therapy), movement ( physical therapy), or other modes. Among physicians, sometimes the term ''medical th ...

because it was one of the early victories in validating the potential of applying

organic chemistry Organic chemistry is a subdiscipline within chemistry involving the science, scientific study of the structure, properties, and reactions of organic compounds and organic materials, i.e., matter in its various forms that contain carbon atoms.Clay ...

to the

synthesis Synthesis or synthesize may refer to: Science Chemistry and biochemistry *Chemical synthesis, the execution of chemical reactions to form a more complex molecule from chemical precursors **Organic synthesis, the chemical synthesis of organi ...

of chemicals that would fight infections with good specificity while presenting

adverse effect An adverse effect is an undesired harmful effect resulting from a Pharmaceutical drug, medication or other Surgery#Definitions, intervention, such as surgery. An adverse effect may be termed a "side effect", when judged to be secondary to a main ...

profiles small enough that benefit would outweigh harm, relative to the contemporary alternative of little to no

efficacious Efficacy is the ability to perform a task to a satisfactory or expected degree. The word comes from the same roots as '' effectiveness'', and it has often been used synonymously, although in pharmacology a distinction is now often made between ...

treatment for many debilitating diseases. In other words, it expanded the evidence that the hope for great potential of

antimicrobial chemotherapy Antimicrobial chemotherapy is the clinical application of antimicrobial agents to treat infectious disease. There are five types of antimicrobial chemotherapy: * Antibacterial chemotherapy, the use of antibacterial drugs to treat bacterial infecti ...

shown by

Paul Ehrlich Paul Ehrlich (; 14 March 1854 – 20 August 1915) was a Nobel Prize-winning German physician and scientist who worked in the fields of hematology, immunology, and antimicrobial chemotherapy. Among his foremost achievements were finding a cure ...

and others was worth pursuing with more research—and that early wins such as

arsphenamine Arsphenamine, also known as Salvarsan or compound 606, is a medication, drug that was introduced at the beginning of the 1910s as the first effective treatment for syphilis, relapsing fever, and African trypanosomiasis. This Organoarsenic chemist ...

were more than just isolated flukes. This was a time period when organic chemistry's largest economic applications included textile dyes, explosives, munitions, and chemical weapons but not yet pharmaceuticals. The fact that systematic, iterative experiments had eventually synthesized an antimalarial drug that was 30 times more effective than

quinine Quinine is a medication used to treat malaria and babesiosis. This includes the treatment of malaria due to '' Plasmodium falciparum'' that is resistant to chloroquine when artesunate is not available. While sometimes used for nocturnal leg ...

while being safe enough to use (relative to the bleak alternatives of the era) supported the concept of modern pharmaceutical research laboratories as it would develop in coming decades. A large trial of pamaquine performed by the

Royal Army Medical Corps The Royal Army Medical Corps (RAMC) is a specialist corps in the British Army which provides medical services to all Army personnel and their families, in war and in peace. The RAMC, the Royal Army Veterinary Corps, the Royal Army Dental Corps ...

and the British

Indian Medical Service The Indian Medical Service (IMS) was a military medical service in British India, which also had some civilian functions. It served during the two World Wars, and remained in existence until the independence of India in 1947. Many of its officer ...

in 1929 showed for the first time that it was possible to prevent relapse of vivax malaria. Prior to this, it was understood that patients with vivax malaria would suffer from relapses, but there was no treatment that could prevent the relapses from occurring. The relative weights of treatment benefit and harm change over decades as science advances. About a decade after pamaquine became available,

chloroquine Chloroquine is a medication primarily used to prevent and treat malaria in areas where malaria remains sensitive to its effects. Certain types of malaria, resistant strains, and complicated cases typically require different or additional medi ...

arrived, and about a decade after that,

arrived. Pamaquine is more toxic and less efficacious than

; therefore, pamaquine is no longer routinely used, and of the two, only primaquine is currently recommended by the

References

{{Antimalarials Antimalarial agents Quinolines Phenol ethers Diethylamino compounds