Jasoprim

Indications

Primaquine is an antimalarial medicine. It is used after standard treatment of Plasmodium vivax or Plasmodium ovale malaria to kill the dormant liver stages (hypnozoites) and prevent relapse, which is called radical cure. A single low dose is also used in falciparum malaria to stop the infection from spreading to mosquitoes. It is sometimes used, with Clindamycin, for a type of pneumonia (Pneumocystis) under specialist care.

How It Works

Primaquine is an 8-aminoquinoline. It is thought to damage the parasite's energy-producing structures (mitochondria) through reactive oxygen products. It is active against the liver forms and the sexual blood forms (gametocytes) of the parasite, but works poorly on the blood forms that cause fever, so it is given together with or after another antimalarial.

Dosage and Administration

Dosing follows national malaria guidelines and is based on body weight, as prescribed. For vivax radical cure in adults, a common regimen is 15 mg (base) once daily for 14 days, given after or with Chloroquine or an artemisinin combination. A single low dose is used for falciparum transmission blocking. Take with food to reduce stomach upset. Complete the full course. A G6PD test is recommended before the 14-day course.

Interactions

• Medicines that can break down red blood cells or suppress the bone marrow (such as Dapsone, Sulfonamides, Nitrofurantoin): higher risk of haemolysis or low blood counts.
• Quinacrine: should not be used together.
• Medicines that prolong the QT interval (such as some antiarrhythmics, antipsychotics, Macrolide and Fluoroquinolone antibiotics, Quinine): use with care.

Contraindications

• Severe G6PD deficiency (a common inherited enzyme deficiency), because it can cause dangerous breakdown of red blood cells.
• Pregnancy.
• Breastfeeding an infant who is G6PD deficient or whose G6PD status is unknown.
• Conditions with a tendency to low white cells, such as active rheumatoid arthritis or lupus, and use with Quinacrine.
• Allergy to Primaquine.

Side Effects

Common effects include stomach cramps, nausea, vomiting and heartburn, which are reduced by taking it with food. It may cause mild anaemia, and rarely methaemoglobinaemia (bluish lips), low white cell counts or irregular heartbeat.

Get urgent medical help if you notice dark (red, brown or black) urine, yellow eyes or skin, sudden paleness, weakness, breathlessness or a fast heartbeat (signs of haemolysis); bluish lips or fingers; fever or sore throat; or signs of a severe allergic reaction.

Pregnancy and Lactation

Primaquine must not be used in pregnancy, because the unborn baby's G6PD status is unknown and it could cause haemolysis in the baby; radical cure is delayed until after delivery and breastfeeding, with weekly Chloroquine prevention in the meantime if advised. Breastfeeding women can take it only if the infant has been tested and has normal G6PD activity.

Precautions and Warnings

Testing for G6PD deficiency before treatment is strongly advised. People with mild G6PD deficiency may be treated with a special weekly schedule under close medical supervision. Stop and seek help at once if urine darkens. Blood counts may be checked during treatment. Tell your doctor if you have heart rhythm problems.

Overdose

Overdose may cause stomach pain, vomiting, haemolysis, methaemoglobinaemia with blue skin, and heart rhythm problems. Seek emergency medical help.

Therapeutic Class

Antimalarial, 8-aminoquinoline.

Storage

Store below 30°C in a dry place, away from light and out of the reach of children.