The pill debossed with “IP 272” is a widely prescribed prescription antibiotic combination containing Sulfamethoxazole (800 mg) and Trimethoprim (160 mg), commonly referred to as Sulfamethoxazole/Trimethoprim Double Strength (SMZ-TMP DS) or by brand names such as Bactrim DS and Septra DS.
Pill Identification
Attribute – Visual / Technical Details
- Imprint – IP 272 (debossed on one side, often bisected)
- Active Ingredients – Sulfamethoxazole (800 mg) / Trimethoprim (160 mg)
- Strength Class – Double Strength (DS)
- Color – White
- Shape – Oval
- Size – 19 mm
- Manufacturer – Amneal Pharmaceuticals LLC
- Drug Class – Sulfonamides / Folate Antagonists
- Controlled Status – Non-controlled prescription drug
Mechanism of Action
Sulfamethoxazole and trimethoprim act synergistically to block two consecutive steps in the bacterial synthesis of tetrahydrofolic acid (essential for bacterial DNA, RNA, and protein synthesis):
- Sulfamethoxazole inhibits the enzyme dihydropteroate synthase, competing with para-aminobenzoic acid (PABA) to prevent the formation of dihydrofolic acid.
- Trimethoprim inhibits the enzyme dihydrofolate reductase (DHFR), blocking the reduction of dihydrofolic acid to tetrahydrofolic acid.
By attacking the metabolic pathway at two distinct stages, the combination achieves bactericidal action against susceptible bacterial strains at concentrations where either drug alone would only be bacteriostatic.
Common Indications and Dosage Guidance
- Note: Dosage depends on infection type, severity, patient age, and renal clearance. Always follow exact prescribing instructions.
- Uncomplicated Urinary Tract Infections (UTIs): 1 tablet (800/160 mg) every 12 hours for 3 to 7 days.
- Acute Otitis Media & Acute Exacerbations of Chronic Bronchitis: 1 tablet every 12 hours for 10 to 14 days.
- Traveler’s Diarrhea & Shigellosis: 1 tablet every 12 hours for 5 days.
- Bacterial Skin & Soft Tissue Infections (including community-acquired MRSA): 1 to 2 tablets every 12 hours for 7 to 10 days.
- Pneumocystis jirovecii Pneumonia (PCP/PCC):
- Prevention: 1 tablet daily or 1 tablet three times weekly.
- Treatment: High weight-based dosing split across 3 to 4 divided doses daily for 14 to 21 days.
Side Effects
Common Side Effects
- Gastrointestinal distress (nausea, vomiting, loss of appetite)
- Mild skin rash or itchiness
- Headache or dizziness
Severe Side Effects (Seek Immediate Medical Care)
- Severe Cutaneous Reactions: Stevens-Johnson Syndrome (SJS) or Toxic Epidermal Necrolysis (TEN) presenting as flu-like symptoms followed by a painful, spreading rash and blistering.
- Blood Dyscrasias: Agranulocytosis, aplastic anemia, leukopenia, or severe thrombocytopenia (unusual bruising or bleeding, weakness, persistent fever).
- Electrolyte Imbalance: Hyperkalemia (high blood potassium levels), which can cause irregular heart rhythms.
- Hepatic Dysfunction: Jaundice (yellowing of eyes/skin), dark urine, abdominal pain.
- Clostridioides difficile Diarrhea: Persistent, severe watery diarrhea.
- Renal Impairment: Interstitial nephritis or crystalluria (crystals in urine).
Precautions and Drug Interactions
- Hydration: Patients should maintain adequate fluid intake to reduce the risk of kidney stone formation or crystalluria.
- Photosensitivity: Increases skin sensitivity to sunlight. Avoid prolonged UV or direct sun exposure and apply broad-spectrum sunscreen.
- Renal Monitoring: Dosages must be reduced if creatinine clearance drops below 30 mL/min.
- Significant Drug Interactions:
- Warfarin: Inhibits warfarin metabolism, significantly increasing INR and bleeding risk.
- ACE Inhibitors / ARBs / Spironolactone: Compounds the risk of life-threatening hyperkalemia.
- Methotrexate: Increases methotrexate toxicity due to displacement from plasma proteins and reduced renal excretion.
- Sulfonylureas (e.g., Glipizide): Enhances hypoglycemic effects, risking severe low blood sugar.
- Phenytoin: Extends the half-life of phenytoin, increasing toxicity risk.
Warnings and Contraindications
- Sulfa Allergy: Contraindicated in individuals with known hypersensitivity to sulfonamides or trimethoprim.
- Infants: Contraindicated in pediatric patients under 2 months of age due to the risk of kernicterus (brain damage caused by severe jaundice).
- Pregnancy: Avoid during the first trimester (risk of neural tube defects from folate antagonism) and the late third trimester near delivery (risk of kernicterus in the newborn).
- Lactation: Excreted in breast milk; avoid nursing infants under 2 months or those with G6PD deficiency.
- Pre-existing Conditions: Use with extreme caution in patients with hepatic or renal impairment, severe allergies, asthma, G6PD deficiency (risk of hemolysis), or folate deficiency (e.g., chronic alcoholism or elderly patients).