Dosing and uses of Sulfadiazine
Adult dosage forms and strengths
tablet
- 500mg
Load
2-4 g PO
Maintenance
2-4 g/day divided 3-6x/day PO
Prophylaxis of Recurrent Rheumatic Fever
>30 kg: 1 g/day
<30 kg: 500 mg/day
Toxoplasmosis
Given with Pyrimethamine & Folinic Acid
1-1.5 g QID us. for 3-4 weeks
Prophylaxis (in patients with HIV): 0.5-1 g q6hr with pyrimethamine (25-75 mg/day PO) & folinic acid (10-25 mg/day PO)
Other Information
Asymptomatic meningococcal carriers: 1 g BID x2 days
Monitor: renal function, CBC
Other Indications & Uses
Burkholderia pseudomallei, Chlamydia trachomatis,Nocardia asteroides & brasiliensis, Mycobacterium smegmatis, Mycobacterium chelonae, Mycobacterium fortuitum
First Line:Mycobacterium smegmatis, Nocardia asteroides & brasiliensis
Pediatric dosage forms and strengths
tablet
- 500mg
Load (>2 Months Old)
75 mg/kg PO Or
2 g/sq.meter PO
Maintenance (>2 Months Old)
150 mg/kg/day divided q4- 6hr PO, Or
4 g/sq. meter/day divided q4 -6hr PO
No more than 6 g/day
Toxoplasmosis
Given with pyrimethamine and folinic acid
100-200 mg/kg/day divided q6hr PO x3-4 weeks
Infants <2 months old: 25 mg/kg/day divided QID PO
Prophylaxis (in patients with HIV): 85-120 mg/kg/day divided BID, TID or QID with pyrimethamine (1 mg/kg or 15 mg/sq.meter daily-maximum dose 25 mg) & folinic acid (5 mg every third day)
Congenital Toxoplasmosis
Given with pyrimethamine and folinic acid
100 mg/kg/day divided q6hr PO x 12 months
Other Information
Prophylaxis of recurrent rheumatic fever: see Adult Dosing
Monitor: renal function, CBC
Sulfadiazine adverse (side) effects
>10%
Diarrhea (33%)
Headache (33%)
Reversible oligospermia (33%)
Anorexia
Gastric distress
Nausea
Photosensitivity
Vomiting
1-10%
Allergic reactions-rash
Aplastic anemia
Dizziness
Hypersensitivity
Itching
Thyroid fuction disturbance
Franulocytopenia
Thrombocytopenia
Frequency not defined
Lyell's syndrome
Sstevens Johnson syndrome
Rash
Fever
Granulocytopenia
Hemolytic anemia
Leukopenia
Hepatitis
Jaundice
Hematuria
Acute nephropathy
Intestinal nephritis
Warnings
Contraindications (additional)
Should not be used for group A beta-hemolytic strep infections
Documented megaloblastic or folate deficiency anemia, obstructive uropathy
Cautions (additional)
Drink 250 mL water w/ each dose & frequently throughout day while taking sulfadiazine
Adverse Drug Reactions
Lyell's syndrome, stevens Johnson syndrome, itching, rash, photosensitivity, thyroid function disturbance, anorexia, diarrhea, nausea, vomiting, dizziness, fever, headache, aplastic anemia, granulocytopenia, hemolytic anemia, leukopenia, thrombocytopenia, hepatitis, jaundice, hematuria, acute nephropathy, intestinal nephritis
Pregnancy and lactation
Pregnancy category: C
Lactation: enters breast milk; risk of kernicterus if infant <2 mo
Pregnancy categories
A: Generally acceptable. Controlled studies in pregnant women show no evidence of fetal risk.
B: May be acceptable. Either animal studies show no risk but human studies not available or animal studies showed minor risks and human studies done and showed no risk.
C: Use with caution if benefits outweigh risks. Animal studies show risk and human studies not available or neither animal nor human studies done.
D: Use in LIFE-THREATENING emergencies when no safer drug available. Positive evidence of human fetal risk.
X: Do not use in pregnancy. Risks involved outweigh potential benefits. Safer alternatives exist.
NA: Information not available.
Pharmacology of Sulfadiazine
Absorption: well absorbed
Distribution: sulfadiazine is distributed into most body tissues; appears to cross cell membranes freely; at a plasma concentration of 100 mcg/mL
Protein Bound: approximately 32-56%
Elimination: largely in urine; urinary concentrations usually are 10-25 times those attained in serum
Mechanism of action
Exerts bacteriostatic action through competitive antagonism with para-aminobenzoic acid (PABA). Microorganisms that require exogenous folic acid and do not synthesize folic acid are not susceptible to the action of sulfonamides
