Pharmacology resources

1. Age

2. Hepatic function: Drugs avoided in hepatic failure- Erythromycin, Tetracyclines, Pyrazinamide, Pefloxacin, Nalidixic acid

3. Renal function: Drugs avoided in renal failure- Tetracyclines (except Doxycycline), Nalidixic acid.

4. Site of Infection: Pus, penetration barriers

5. Drug allergy

6. Immunocompromised patients

7. Pregnancy: Safe- β lactams, Erythromycin

8. Lactation: Safe- Cephalosporins, Erythromycin

9. Genetic: Primaquine, sulfonamides, fluoroquinolones can cause haemolysis in G6PD deficient patients.

Drug related factors

1. Spectrum

2. Type of activity

3. Sensitivity of organism

4. Relative toxicity: Erythromycin/Clindamycin, β lactam/Aminoglycoside

5. Pharmacokinetics:

• Concentration dependant- Fluoroquinolones, Aminoglycoside
• Time dependant- β lactams, Glycopeptides, Macrolides
• Good tissue penetration- Fluoroquinolones
• High CSF conc.- Cefuroxime, Certriaxone, chloramphenicol, ciprofloxacin
• Poor CSF conc.- Penicillins, Aminoglycosides.

6. Route of administration:

• i.v. only- Aminoglycosides, Penicillin G, vancomycin, ceftriaxone, 4^th generation cephalosporins.

7. Clinical evidence

8. Cost.

Based on clinical diagnosis

1. Clinical diagnosis is sufficient- e.g. syphilis, diphtheria, tetanus, cholera, trachoma, trush, tuberculosis, leprosy, amoebiasis, herpes simplex.

2. Good guess about type of organism- e.g. tonsillitis, URTI, otitis media, boils, etc.

3. Based on culture and sensitivity report- e.g. meningitis, bronchopneumonia, osteomyelitis, UTI, wound infection.

• Acute- empirical therapy;
• Chronic- wait for report.