Drug Guide

Generic Name

Sulfamethoxazole

Brand Names Gantanol, Gantanol-ds, Urobak

Classification

Therapeutic: Antibacterial, Sulfonamide

Pharmacological: Sulfonamide Antibiotic

FDA Approved Indications

  • Urinary tract infections (UTIs)
  • Otitis media
  • Bronchitis caused by susceptible bacteria
  • Traveler's diarrhea (in combination with trimethoprim)

Mechanism of Action

Sulfamethoxazole inhibits bacterial dihydropteroate synthase, blocking folic acid synthesis which is essential for bacterial growth.

Dosage and Administration

Adult: Typically, 400 mg every 12 hours for UTIs; dosage varies based on infection severity and site.

Pediatric: Dose determined based on weight, usually 8-12 mg/kg/day divided into two doses.

Geriatric: Adjust based on renal function and indication; monitor closely for adverse effects.

Renal Impairment: Dose adjustment required; usually reduce frequency or dose depending on degree of impairment.

Hepatic Impairment: Use with caution; no specific dose adjustments, but monitor liver function.

Pharmacokinetics

Absorption: Well absorbed from the gastrointestinal tract.

Distribution: Widely distributed, including into body fluids and tissues.

Metabolism: Minimal hepatic metabolism, metabolites are excreted renally.

Excretion: Primarily excreted unchanged in the urine.

Half Life: approximately 10 hours.

Contraindications

  • Hypersensitivity to sulfonamides or other sulfa drugs.
  • Severe hepatic or renal impairment without proper dose adjustment.

Precautions

  • Use with caution in patients with folate deficiency, elderly, or those on other medications affecting renal function.
  • Pregnancy Category C; avoid near term due to risk of kernicterus in neonates.
  • Lactation: Crosses into breast milk; risk of bilirubin displacement.

Adverse Reactions - Common

  • Rash (Common)
  • Nausea, vomiting (Common)
  • Loss of appetite (Common)

Adverse Reactions - Serious

  • Stevens-Johnson syndrome, toxic epidermal necrolysis (Rare)
  • Hematologic reactions (e.g., agranulocytosis, aplastic anemia) (Rare)
  • Crystalluria and renal damage (Rare)

Drug-Drug Interactions

  • Methotrexate (increased toxicity)
  • Warfarin (increased anticoagulant effect)
  • Methicillin (competes for renal excretion)

Drug-Food Interactions

N/A

Drug-Herb Interactions

N/A

Nursing Implications

Assessment: Monitor for signs of allergic reactions, hematologic changes, renal function, and liver function.

Diagnoses:

  • Risk for allergic reaction
  • Impaired renal function

Implementation: Administer with plenty of water to prevent crystalluria. Monitor blood counts.

Evaluation: Assess resolution of infection, monitor for adverse effects.

Patient/Family Teaching

  • Complete full course of therapy.
  • Report any signs of rash, fever, jaundice, or unusual bleeding.
  • Drink plenty of fluids to reduce risk of crystalluria.
  • Use sunscreen; photosensitivity may occur.

Special Considerations

Black Box Warnings:

  • Hypersensitivity reactions, including Stevens-Johnson syndrome, and toxic epidermal necrolysis, which can be life-threatening.

Genetic Factors: G6PD deficiency may predispose to hemolytic anemia with sulfonamides.

Lab Test Interference: False increases in serum creatinine levels due to interference with measurement.

Overdose Management

Signs/Symptoms: Nausea, vomiting, dizziness, seizures, renal failure.

Treatment: Supportive care, hydration, and correction of electrolyte imbalances. Hemodialysis may be considered in severe cases.

Storage and Handling

Storage: Store at room temperature, protected from light.

Stability: Stable until expiration if kept properly.

🛡️ 5 Critical Medication Safety Tips for Nurses

1

Triple-Check High-Risk Medications

Always have another nurse verify insulin, heparin, warfarin, and chemotherapy drugs. These "high-alert" medications cause the most serious errors. Check concentration, dose calculation, and pump settings twice.

2

Know Look-Alike, Sound-Alike Drugs

Common mix-ups: hydromorphone/morphine, Celebrex/Celexa, Zyprexa/Zyrtec. Always use BOTH generic and brand names, read labels twice, and use barcode scanning when available. One wrong letter can be fatal.

3

Assess Before AND After Giving Meds

Check vitals before cardiac meds, pain levels before analgesics, and blood glucose before insulin. Always reassess within 30 minutes to evaluate effectiveness and watch for adverse reactions.

4

Watch for Drug Interactions

Common dangerous combinations: warfarin + aspirin (bleeding), ACE inhibitors + potassium (hyperkalemia), digoxin + diuretics (toxicity). Always check drug interactions before administering new medications.

5

Educate Your Patients

Teach patients medication names, purposes, major side effects, and what to report. Informed patients catch errors and improve compliance. Always encourage questions - an educated patient is a safer patient.

⚡ Remember: When in doubt, don't give it out! It's always safer to double-check than regret later.

⚠️ Medical Disclaimer

This drug guide is for educational purposes only and is NOT intended for clinical use. Always consult current prescribing information, healthcare providers, and institutional protocols before administering any medication. Do not use this information for patient care decisions.