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Trimethoprim - Coggle Diagram
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Trimethoprim
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MOA
- Trimethoprim is diaminopyrimidine related pyrimethamine (folate antagonist)
- it selectively inhibits bacterial dihydrofolate reductase
Pharmacokinetics
- Given orally
- Fully absorbed in GIT
- Widely distributed in tissues and body fluid
- Half-life: 10hrs
- High conc in lungs and kidneys
- Concentrated in acidic prostate tissues & vaginal fluids
- It is a weak base
- Treat UTI & RTI
- Partly metabolized in liver, excreted in urine
Spectrum of activity
- Bacteriostatic
- Active against aerobic gram-ve and few gram+ve bac.:
- Salmonlla typhi
- Serratia
- Enterobacter
- Pneumocystis
- Sulfonamide-resistant strains of Staph. aureus, Pyogenes, Shigella, E. coli, influenzae, gonococci, meningococci
- Combination: sulfonamide/trimethoprim - bacteriocidal
Adverse effects
- nausea, vomiting, skin rash
- folate deficiency - resulting megaloblastic anemia
- *can be prevented by folinic acid
Use
- Urinary tract infections & Prostatic infections
- single dose therapy with 4 tabs for acute cystitis
- courses 3-10days
- Respiratory tract infections: chronic bronchitis, facio-maxillary infections, H. influenza
- caused by: Pneumocystis jiroveci, Nocardia asteroides
- Typhoid
- Bacterial diarrhea & dysentery
- Pneumonia - Pneumocystis jiroveci
- Chancroid - bacterial sexually transmitted infection
- bacterial prostatitis and vaginitis
Resistance
- Mutational or plasmid mediadated acquisition of DHFRase having low affinity
- Combinations reduced responsiveness over 20% originally sensitivity
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