Proguanil

Proguanil

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Proguanil

Proguanil, also known as chlorguanide and chloroguanide, is a medication used to treat and prevent malaria. It is often used together with chloroquine or atovaquone. When used with chloroquine the combination will treat mild chloroquine resistant malaria. It is taken by mouth

Proguanil

Therapeutic indications

Proguanile is an effective antimalarial agent. It is recommended for the prevention and suppression of malaria.

Posology and method of administration

Oral use

Non-immune subjects entering a malarious area are advised to begin treatment with Proguanile 1 week before, or if this is not possible, then at least 2 days before entering the malarious area. The daily dose of Proguanile should be continued throughout exposure to risk and for 4 weeks after leaving the area.

Adults:

Two tablets (200 mg) daily.

Paediatric population:

Under 1 year:    1/4 tablet (25 mg) daily

1 to 4 years:        1/2 tablet (50 mg) daily

5 to 8 years:        1 tablet (100 mg) daily

9 to 14 years:     1 1/2 tablets (150 mg) daily

Over 14 years:   Adult dose daily

The daily dose is best taken with water, after food, at the same time each day.

Provided the tablet fragment gives the minimum amount specified, precise accuracy in children’s dosage is not essential since the drug possesses a wide safety margin.

For a young child, the dose may be administered crushed and mixed with milk, honey or jam.

Older people: There are no special dosage recommendations for the elderly, but it may be advisable to monitor elderly patients so that optimum dosage can be individually determined.

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Pharmacodynamics

Proguanil is a biguanide derivative that is converted to an active metabolite called cycloguanil. It exerts its antimalarial action by inhibiting parasitic dihydrofolate reductase enzyme. It has causal prophylactic and suppressive activity against P. falciparum and cures the acute infection. It is also effective in suppressing the clinical attacks of vivax malaria. However it is slower compared to 4-aminoquinolines.

Mechanism of action

Proguanil inhibits the dihydrofolate reductase of plasmodia and thereby blocks the biosynthesis of purines and pyrimidines, which are essential for DNA synthesis and cell multiplication. This leads to failure of nuclear division at the time of schizont formation in erythrocytes and liver.

Interaction with other medicinal products and other forms of interaction

Antacids

Antacids may reduce the absorption of proguanil, so should be taken at least 2-3 hours apart.

Anticoagulants

Proguanil can potentiate the anticoagulant effect of warfarin and related anticoagulants through a possible interference with their metabolic pathways. Caution is advised when initiating or withdrawing malaria prophylaxis with Proguanile in patients on continuous treatment with anticoagulants.

Live oral typhoid vaccination (Ty21a strain)

Proguanil should be stopped 3 days before and should not be started until 3 days after receiving live oral typhoid vaccination (Ty21a strain).

Boosted protease-inhibitors

When given with boosted protease-inhibitors, reduction in proguanil exposure has been observed. This combination should be avoided when possible.

Fertility, pregnancy and lactation

Pregnancy: There are limited data available from the use of proguanil in pregnant women.

Proguanile should not be used during pregnancy unless, in the judgement of the physician, potential benefit outweighs the risk.

Malaria in pregnant women increases the risk of maternal death, miscarriage, still-birth and low birth weight with the associated risk of neonatal death. Although travel to malarious areas should be avoided during pregnancy, if this is unavoidable effective prophylaxis is therefore strongly advised in pregnant women.

Proguanil is a dihydrofolate reductase inhibitor and adequate folate supplements should be given to pregnant women taking proguanil.

Lactation: Although Proguanile is excreted in breast milk, the amount is insufficient to confer any benefit on the infant. Separate chemoprophylaxis for the infant is required.

Side effects

Proguanil is generally well tolerated, and most people do not experience side effects. However, common side effects include abdominal pain, nausea, headache, and fever. Taking proguanil with food may lessen these side effects

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