Week 10 - Sulfonamides, Trimethoprim, Nitrofurantoin Flashcards
Sulfonamides and Trimethoprim: examples
Sulfamethoxazole, Trimethoprim
Sulfonamides and Trimethoprim: activity
Gram (+) AND gram (-)
E. coli, toxoplasma gondil, PCP
Sulfonamides and Trimethoprim: indications
UTI, including suppression, MRSA, PCP pneumonia
Sulfonamides and Trimethoprim: MOA
Competitively inhibits dihydrofolate synthetase (necessary for conversion of PABA to dihydrofolic acid)
Inhibiting this pathway prevents folic acid synthesis which is important for some bacteria to survive
Sulfonamides and Trimethoprim: ADR
- Crystalluria –> maintain hydration
- Hypersensitivity
- Hemolytic anemia
- Kernicterus (brain damage)
Sulfonamide and Trimethoprim: caution and contraindications
- Avoid in patients with sulfa allergy
- Avoid in patients with G6PD
- Caution in folate deficiency
- Caution in renal impairment
- Alternative agents should be used in pregnancy and lactation
- Avoid in pediatrics <2 months
Nitrofurantoin: activity
Gram (+) AND gram (-) that cause UTIs (e. coli)
Bacteriostatic at [low], bactericidal at [high]
Nitrofurantoin: indications
Uncomplicated UTIs, including long-term suppression of UTIs
Nitrofurantoin: MOA
Activated by bacteria to reactive intermediates that inactivate or alter bacterial ribosomes, leading to inhibition of protein synthesis, aerobic energy metabolism, DNA, RNA, and cell wall synthesis
Nitrofurantoin: ADR
HA, nausea, rash, urine discoloration
Rare: hepatic dysfunction, agranulocytosis, hemolytic anemia, peripheral neuropathy, hypersensitivity reaction
Nitrofurantoin: caution and contraindications
- Avoid if creatinine clearance <30 mL/min
- Caution if creatinine clearance <60 mL/min
- Avoid in G6PD
- Avoid in pregnancy at term (38-42 weeks)
- Avoid in lactation when infant is <1 month (risk for hemolytic anemia)
Sulfonamides, Trimethoprim, Nitrofurantoin: monitoring
- Long term use –> CBC (can cause myelosuppression)
- Chest x-ray in patients who develop cough when on nitrofurantoin
