Applicant/PHRC: Hetero Drugs South Africa (Pty) Ltd.
Product proprietary name: Hetovanil 62,5/25 mg and Hetovanil 250/100 mg
Dosage form and strength: Film coated tablets. Each contains 62,5 mg or 250 mg of Atovaquone and 25
mg or 100 mg of Proguanil HCl.
4.9 Overdose
There is insufficient experience to predict the consequences or suggest specific management of
atovaquone/proguanil overdose. However, in the reported cases of atovaquone overdose, the
observed effects were consistent with known undesirable effects of the medicine. If overdose
occurs, the patient should be monitored and standard supportive treatment applied.
5 PHARMACOLOGICAL PROPERTIES
5.1 Pharmacodynamic properties
Pharmacotherapeutic group: Antiprotozoals, antimalarials,
ATC code: P01B B51
PHARMACOLOGICAL CLASSIFICATION:
A 20.2.6 Medicines against protozoa
Mechanism of Action
The constituents of HETOVANIL, atovaquone and proguanil hydrochloride, interfere with two
different pathways involved in the biosynthesis of pyrimidines required for nucleic acid replication.
The mechanism of action of atovaquone against P. falciparum is via inhibition of mitochondrial
electron transport, at the level of the cytochrome bc1 complex, and collapse of mitochondrial
membrane potential. One mechanism of action of proguanil, via its metabolite cycloguanil, is
inhibition of dihydrofolate reductase, which disrupts deoxythymidylate synthesis. Proguanil also has
antimalarial activity independent of its metabolism to cycloguanil, and proguanil, but not
cycloguanil, is able to potentiate the ability of atovaquone to collapse mitochondrial membrane
potential in malaria parasites. This latter mechanism may explain the synergy seen when
atovaquone and proguanil are used in combination.
Microbiology
Atovaquone has potent activity against Plasmodium spp (in vitro IC50 against P. falciparum 0,23-
1,43 ng/mL).
May 2022
Initial:K.B
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