Description and Composition of Fanasil – pyrimethamine
Table of Contents
Fanasil – pyrimethamine is an antimalarial agent which acts by reciprocal potentiation of its two active pharmaceutical ingredients, Sulfadoxine 500 mg and pyrimethamine 25 mg achieved by a sequential blockage of two enzymes involved in the synthesis of folinic acid in the parasites. By virtue of this marked synergistic action, Sulfadoxine-pyrimethamine is also effective against strains that are resistant to such antimalarial drugs as Chloroquine and other 4-aminoquinoline derivatives or to pyrimethamine alone. It comes in tablets and Syrup dosage forms of Sulfadoxine 500 mg + pyrimethamine 25 mg per tablet and 5ml of the Syrup.
With sulfadoxine-pyrimethamine, the risk of resistance emerging is reduced to a minimum. One of the major advantages of Sulfadoxine-pyrimethamine is that it attacks the different stages of the life cycle of the malaria parasite.
Effective concentration are rapidly attained with a single dose and trophozoites and schizonts eliminated from the biood. The pre-erythrocytic stages are also affected, not however, the secondary exoerythrocytic forms, which may cause recurrence infection with Plasmodium vivax. In such cases, therefore, consideration should be given to following up treatment with sulfadoxine-pyrimethaminethe with primaquine to prevent recurrence. Sulfadoxine-pyrimethamine is compatible with other antimalarial drugs, particularly quinine and with antibiotics. It has no hypoglycemic effect and does not influence the action of antidiabetic agents.
Indications and Uses of Fanasil – pyrimethamine
What is the use of Fanasil – pyrimethamine?
It should also be used for Intermittent Preventive Treatment in Pregnancy (IPT). In combination with other antimalarials, it is used for treatment of falciparum malaria. Sulfadoxine-pyrimethamine has also been found effective in Infections with Toxoplasma gondii and in the prophylaxis of pneumonia due to Pneumocystis carinii.
Contraindications of Fanasil – pyrimethamine:
When should Fanasil – pyrimethamine not be taken?
Sulfadoxine-pyrimethamine is contraindicated in patients with hypersensitivity to sulfonamides. Fetal malformation has been observed in rats when Sulfadoxine-pyrimethamine was administered in early pregnancy. This was due to pyrimethamine, the folic acid antagonist contained in Sulfadoxine-pyrimethamine. Even though pyrimethamine is not known to cause fetal malformation in humans, Sulfadoxine-pyrimethamine should not be administered prophylactically in the first trimester of pregnancy. In already existing malaria infections, the risk of fetal damage from the disease must be balanced against the possible implications of the above-mentioned animal experiments. Sulfadoxine-pyrimethamine should not be employed in premature and newborn infants during the first weeks of life, in view of the immaturity of their enzyme systems. For the same reason, Sulfadoxine-pyrimethamine should not be administered prophylactically in the last two weeks of pregnancy. It is also contraindicated in cases of intolerance to sulfonamides.
Sulfadoxine-pyrimethamine belongs to the antifolate group of antimalarials. There is evidence that folic acid administered concurrently with Sulfadoxine-pyrimethamine can antagonize sulphadoxine action, therefore folic acid supplement should be delayed for one week after the use of Sulfadoxine-pyrimethamine to avoid inhibitory effect on the antimalarial action.
Dosage and administration of Fanasil – pyrimethamine
How should Fanasil – pyrimethamine be taken?
a. Intermittent Preventive Treatment of Malaria in Pregnancy.
One full treatment dose during the second and third trimesters. The last dose should be given not later than one month before the expected date of delivery. (Second trimester starts from sixteen weeks or when the pregnant woman notices the kicking of the baby)
b.As adjunct with other antimalarials:
10 – 20 kg : 1 tablet or 5 mL
21 – 30 kg : 1½ tablets or 7.5 mL
31 – less than 45 kg : 2 tablets or 10 mL
45 kg and above : 3 tablets or 15 mL
A tablet likewise 5ml of its Syrup has Sulfadoxine 500 mg + pyrimethamine 25 mg.
Sulfadoxine- pyrimethamine should be taken only in the doses recommended above. Sulfadoxine-pyrimethamine must not be used in the first trimester of pregnancy.
Side effects of Fanasil – pyrimethamine
What are the side effects of Fanasil – pyrimethamine ?
In the recommended dosage, Sulfadoxine-pyrimethamine is generally well tolerated. As with other drugs containing sulfonamides and/or pyrimethamine, the following side effects and hypersensitivity reactions may occur.
- Drug rash
- Pruritus and
- Slight hair loss been observed.
These reactions are usually mild and regress spontaneously on withdrawal of the drug.
In rare cases, particularly in hypersensitive patients, severe possibly life-threatening skin reactions such as:
- erythema multiforme,
- Stevens-Johnson syndrome and
- Lyell’s syndrome may occur
- Feeling of fullness
- Rarely vomiting,
There have been isolated reports of hepatitis occuring conjointly with administration of Sulfadoxine-pyrimethamine.
In rare cases, leukopenia (usually asymptomatic), rombocytopenia and megaloblastic anemia have been observed. In extremely rare cases, they take the form of agranulocytosis or purpura. As a rule, all these changes regress after withdrawal of the drug.
Other side effects:
- Fever and
- Polyneuritis may occasionally occur.
- Pulmonary infiltrates such as it occur in eosinophilic or allergic alveolitis have been reported in rare instances.
If symptoms such as cough or shortness of breath should occur under Sulfadoxine-pyrimethamine therapy, the drug should be discontinued.
Interactions of Fanasil – pyrimethamine:
What does Fanasil – pyrimethamine interact with?
Concurrent administration of Sulfadoxine-pyrimethamine with trimethoprim or trimethoprim-sulfonamide combinations can result in increased impairment of folic acid metabolism and the consequent hematological side effects, and should therefore be avoided. There have been reports which may indicate an increase in incidence and severity of adverse reactions when chloroquine is used with Sulfadoxine – pyrimethamine compared with the use of Sulfadoxine -pyrimethamine alone.
If skin reactions are observed, the drug should be withdrawn Immediately and a doctor consulted.
- Swidar® drug leaflet