UROPLUS SS
Clinical safety rating: caution
Comprehensive clinical and safety monograph for UROPLUS SS (UROPLUS SS).
Uroplus SS contains sulfamethoxazole and trimethoprim. Sulfamethoxazole inhibits bacterial dihydrofolic acid synthesis by competing with para-aminobenzoic acid (PABA) for dihydropteroate synthase. Trimethoprim inhibits bacterial dihydrofolate reductase, blocking reduction of dihydrofolate to tetrahydrofolate. The sequential blockade of folic acid metabolism produces bactericidal activity.
| Metabolism | Sulfamethoxazole is metabolized primarily via N-acetylation to N4-acetyl-sulfamethoxazole. Trimethoprim undergoes O-demethylation and N-oxidation. Both are primarily excreted in urine. |
| Excretion | Renal: 70–80% as unchanged drug; fecal: 10–20% via biliary elimination; minimal hepatic metabolism. |
| Half-life | Terminal elimination half-life is 18–24 hours, allowing once-daily dosing; steady-state achieved in 3–5 days. |
| Protein binding | 60–70% bound primarily to albumin and alpha-1-acid glycoprotein. |
| Volume of Distribution | 0.35–0.45 L/kg, indicating distribution into total body water and moderate tissue penetration. |
| Bioavailability | Oral: 85–92% due to extensive absorption; intravenous: 100%. |
| Onset of Action | Oral: clinical effect observed within 2–4 hours; intravenous: within 30 minutes. |
| Duration of Action | Approximately 24 hours, supporting once-daily administration; drug concentrations remain above MIC for 12–24 hours post-dose. |
| Molecular Weight | 250.28 Da (sulfamethoxazole component) |
4 grams orally once daily as a single dose or in divided doses for 10 to 14 days for urinary tract infections.
| Dosage form | TABLET |
| Renal impairment | GFR 30-50 mL/min: 4 grams every 18 hours; GFR 15-29 mL/min: 4 grams every 24 hours; GFR <15 mL/min: 4 grams every 48 hours; hemodialysis: 4 grams after each dialysis session. |
| Liver impairment | No specific adjustment recommended; use with caution in severe hepatic impairment (Child-Pugh C) due to limited data. |
| Pediatric use | Children 2 years and older: 50 mg/kg orally once daily (max 4 grams) for 10 to 14 days; children under 2 years: not recommended. |
| Geriatric use | No specific dose adjustment based on age alone; monitor renal function and adjust dose according to creatinine clearance. |
| 1st trimester | Avoid. UROPLUS SS contains sulfonamides which may cause teratogenic effects; first trimester exposure is associated with congenital malformations. |
| 2nd trimester | Caution. Sulfonamides cross placenta; risk of kernicterus in neonates if used near term. |
| 3rd trimester | Contraindicated. Sulfonamides displace bilirubin from albumin, increasing risk of kernicterus in the newborn. |
Clinical note
Comprehensive clinical and safety monograph for UROPLUS SS (UROPLUS SS).
| Placental transfer | Sulfonamides readily cross the placenta with fetal concentrations reaching 50-90% of maternal levels. |
| Breastfeeding | Sulfonamides are excreted in breast milk. Risk of kernicterus in neonates with G6PD deficiency or if infant is <1 month old. Use only if benefit outweighs risk. |
■ FDA Black Box Warning
None
| Serious Effects |
Hypersensitivity to sulfonamidesPorphyriaSevere hepatic or renal impairmentPregnancy at termInfants <2 months of age
| Precautions | Risk of severe hypersensitivity reactions (Stevens-Johnson syndrome, toxic epidermal necrolysis), hematologic toxicity (agranulocytosis, aplastic anemia), hepatic necrosis, renal toxicity (crystalluria, interstitial nephritis), hyperkalemia in elderly, and increased risk of kernicterus in neonates. |
| Food/Dietary | Avoid alcohol (potential disulfiram-like reaction). Take with food if GI upset occurs. Maintain adequate fluid intake (≥2 L/day) to prevent crystalluria. No specific food restrictions but avoid high-potassium foods if hyperkalemia risk (e.g., bananas, oranges, potatoes). |
Loading safety data…
| Lactation Rating |
| L3 (Moderately Safe) |
| Teratogenic Risk | UROPLUS SS (sulfamethoxazole/trimethoprim) is contraindicated in pregnancy due to teratogenic risks. Sulfamethoxazole crosses the placenta and may cause kernicterus in the newborn if used near term. Trimethoprim is a folate antagonist and may increase risk of neural tube defects, cardiovascular malformations, and oral clefts in first trimester. Use in second and third trimester is associated with increased risk of preterm birth, low birth weight, and neonatal jaundice. Risk is highest in first trimester and near term. |
| Fetal Monitoring | Monitor maternal CBC, renal function, and urinalysis. Assess for hypersensitivity reactions. In neonates, monitor bilirubin levels and signs of kernicterus. Perform ultrasound for fetal growth if used beyond first trimester. Consider folate supplementation. |
| Fertility Effects | Trimethoprim may reduce dihydrofolate reductase activity, potentially affecting spermatogenesis and oocyte maturation. Reversible impairment of fertility has been reported in animal studies at high doses. Clinical relevance in humans is uncertain but may cause transient reduction in fertility. |
| Clinical Pearls | UROPLUS SS is a combination of sulfamethoxazole and trimethoprim (co-trimoxazole) used for urinary tract infections. Monitor renal function and avoid in severe renal impairment (CrCl <15 mL/min). Caution in elderly, folate deficiency, or sulfonamide allergy. Increased risk of hyperkalemia with high-dose trimethoprim, especially in patients on ACE inhibitors or potassium-sparing diuretics. Photosensitivity possible; advise sun protection. Use with caution in G6PD deficiency. |
| Patient Advice | Take with a full glass of water to prevent crystalluria. · Complete the full course even if symptoms improve. · Avoid prolonged sun exposure; use sunscreen and protective clothing. · Report rash, sore throat, fever, or unusual bruising/bleeding immediately. · Do not take if allergic to sulfa drugs or trimethoprim. · May cause dizziness; avoid driving if affected. |