Drug reference

Sulfadiazine

Sulfonamide · Antiparasitic

Also known as Sodium sulfadiazine

SulfonamideAntiparasiticATC null

CDSCO approvedSchedule H

EXCRETION

—

not curated

INTERACTIONS

12 major

SEVERE in our sources

PREGNANCY

Administered to pregnant mothers after the first 12-14 weeks of pregnancy in combination with pyrimethamine and folinic acid if fetal Toxoplasma gondii infection is detected.

FDA category + note

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Mechanism

Sulfadiazine is an antifolate drug, commonly used in combination with pyrimethamine and folinic acid for its therapeutic effects. As a weak acid with a pKa of 6.5, its ionization is pH-dependent, influencing its ability to diffuse across lipid membranes and distribute throughout the body.

Indications

ToxoplasmosisToxoplasmic encephalitisAcute acquired toxoplasmosis in pregnancy (to prevent transmission to the fetus, if fetal infection is detected, administered to the mother after the first 12-14 weeks of pregnancy)Congenital toxoplasmosisToxoplasmosis (in combination with pyrimethamine)Nocardia spp. infections (alternative to TMP-SMX)Acute toxoplasmosistoxoplasmosis (with other agents)Prophylaxis for meningococcal meningitis (during an epidemic)combination with trimethoprim (cotrimazine) for uses similar to cotrimoxazoleCNS toxoplasmosis (in combination with pyrimethamine and folinic acid)

Dosing

Adult: 1 g daily in divided doses, doses to be taken after meals, then increased if necessary up to 3 g daily in divided doses (max. per dose 1 g), dose to be increased over 1 week Maintenance of remission of mild ulcerative colitis ▶ ▶ BY MOUTH ▶ Adult: Maintenance 500 mg twice daily, dose to be taken after food l INTERACTIONS l SIDE-EFFECTS → Appendix 1: olsalazine .…

Pharmacokinetics

Peak effect

3 to 6 h

Half-life

4-8 hr

Protein binding

About 55% bound to plasma protein

Metabolism

20-40% acetylated (acetylated derivative is less soluble in acidic urine)

Excretion

rapidly excreted in urine

Contraindications

risk of crystalluria

Side effects

Common

NauseaVomitingAnorexiaBone marrow suppressionHypersensitivity reactionscrystalluria (acetylated derivative is less soluble)Hypersensitivity reactions (allergy usually associated with sulfonamide moiety)Gastrointestinal effectsgi disturbancesallergic skin reactionscrystalluria

Serious

Crystalluria (especially in dehydrated patients)
Kernicterus (in neonates due to bilirubin displacement)
Haemolysis (in G-6-PD deficient patients)
Nephrotoxicity
Hematologic effects (leukopenia, thrombocytopenia, granulocytopenia)
Risk in third trimester of pregnancy
severe skin reactions (toxic epidermal necrolysis, erythema multiforme, stevens-johnson syndrome)
agranulocytosis
aplastic anemia
hypersensitivity of the respiratory tract
hepatitis
interstitial nephritis
hypoglycemia
aseptic meningitis

Pregnancy & lactation

Pregnancy

Administered to pregnant mothers after the first 12-14 weeks of pregnancy in combination with pyrimethamine and folinic acid if fetal Toxoplasma gondii infection is detected.