Toxoplasmosis is caused by infection with the protozoan parasite Toxoplasma gondii. Toxoplasmosis in immunocompetent individuals is usually asymptomatic and if symptomatic infection does occur it is usually self-limiting. Very rarely myocarditis or encephalitis may occur. Patients with impaired immunity may develop serious complications such as encephalitis, myocarditis, and pneumonitis.

The treatment of choice is a combination of pyrimethamine and sulphadiazine. Calcium folinate should also be given every third day during treatment to counteract megaloblastic anaemia. Treatment is ideally continued for several weeks after clinical cure. Prolonged even life long, maintenance therapy should be considered for AIDS patients since the tissue cyst forms of T.gondii will not have been affected by the initial treatment.

Congenital toxoplasmosis is not a problem in women who have toxoplasma antibody before conception but primary toxoplasmosis during early pregnancy is serious because of the risk of transplacental transmission, which may result in foetal death or congenital toxoplasmosis.

Pyrimethamine
Tablet, 25mg

Indications: - pyrimethamine is indicated in combination with sulfapyrimedine - type sulfonamide in the treatment of toxoplasmosis caused by Toxoplasma gondii.

Cautions: - pregnancy and breast-feeding, hepatic function impairment and in those patients hypersensitive to pyrimethamine.

Drug interactions - bone marrow depressants, folate antagonists.

Contraindications - pregnancy (14 or 16 weeks), hypersensitivity, history of seizures disorders, anaemia and bone marrow depression.

Side effects: - Atrophic glossitis (pain, burning, or inflammation of the tongue, change in or loss of taste), blood dyscrasias, specifically agranulocytosis (fever, sore throat), megaloblastic anaemia (unusual tiredness, or weakness), or thrombocytopenia (unusual bleeding or bruising), GIT disturbance (anorexia, Nausea, vomiting, diarrhoea), Hypersensitivity (skin rash).

Dose and Administration:

Toxoplasmosis (in second and third trimesters of pregnancy), by mouth, adult 25mg daily for 3-4 weeks

Toxoplasmosis in NEONATES, by mouth, 1 mg/kg daily; duration of treatment depends on whether neonate has overt disease-continue for 6 months, or is without overt disease but, born to mother infected during pregnancy-treat for 4 weeks, followed by further courses if infection confirmed.

Toxoplasmosis in immunodeficiency, by mouth, Adult, 200mg in divided doses on first day, then 75-100mg daily for at least 6 weeks, followed by a suppressive dose of 25-50mg daily.

Chorioretinitis, by mouth, Adult 75mg daily for 3 days then 25mg daily for 4 weeks; in unresponsive patients, 50 mg daily for a further 4 weeks

Note: for the treatment of toxoplasmosis, pyrimethamine must always be taken with sulfadiazine. Take with meals and continue medicine with full time of treatment.

Storage: - at room temperature in a tight, light-resistant container.

Sulphadiazine
Tablet, 500mg

Indications: - toxoplasmosis (with pyrimethamine); rheumatic fever

Cautions: - hepatic and renal impairment; maintain adequate fluid intake (to avoid crystalluria); avoid in blood disorders (unless under specialist supervision); monitor blood counts and discontinue immediately if blood disorder develops; rashes - discontinue immediately; elderly; asthma, G6PD deficiency; pregnancy - avoid in first trimester, but may be given thereafter if danger of congenital transmission; breast feeding; see also interactions.

Drug interactions: - ciclosporin, glibenclamide, pyrimethamine & co-trimoxazole (increased risk of antifolate effect), Warfarin

Contraindications: - hypersensitivity to sulfonamides, severe renal failure or severe hepatic impairment, porphyria.

Side effects: - nausea, vomiting, diarrhea, headache, hypersensitivity reactions including rashes, pruritus, photosensitivity reactions, exfoliative dermatitis, and erthema nodosum; rarely, erythemamultiforme and toxic epidermal necrolysis; crystalluria resulting in haematuria, oliguria, anuria, blood disorders including granulocytopenia, agranulocytosis, aplastic anaemia, purpura - discontinue immediately, liver damage, pancreatitis, antibiotic - associated colitis, eosinophilia, cough and shortness of breath, pulmonary infiltrates, aseptic meningitis, depression, convulsions, ataxia, tinnitus, and electrolyte disturbances.

Dose and Administrations: -

Toxoplasmosis (in second and third trimesters of pregnancy), by mouth, Adult 3g daily in 4 divided doses.

Toxoplasmosis in neonates, by mouth, 85mg/kg daily in 2 divided doses; duration of treatment depends on whether the neonate has overt disease continue for 6 months, or is without overt disease but born to mother infected during pregnancy - treat for 4 weeks, followed by further courses, if infection confirmed.

Toxoplasmosis in immunodeficiency, by mouth, Adult, 4 - 6g daily in 4 divided doses for at least 6 weeks followed by a suppressive dose of 2 - 4g daily.

Note: - For the treatment of toxoplasmosis, Sulfadiazine must always be taken with pyrimethamine.

Storage: - below 30°C in a tight container, protect from light.