Antibiotics- penicillin

penicillin and it's clinical implications

1. A ntibiotics ‘Start smart – then focus’

2. Classification

3. Penicillin NATURAL PENICILLIN : benzylpenicillin , phenoxymethyl penicillin PENICILLINASE RESISTANT PENICILLIN: Methicillin, Cloxacillin , Dicloxacillin AMINOPENICILLIN: Ampicillin, Amoxicillin CARBOXYPENICILLIN : Carbenicillin UREIDOPENCILLIN: Piperacillin

4. Mechanism of action Competitive inhibition of transpeptidase (penicillin binding protein) Inhibition of cell wall peptidoglycan synthesis Bacterial cell swells and burst due to hyperosmotic interior of cell

5. Antibacterial spectrum Natural penicillin : Treponema pallidum , meningococci , most streptococci Penicillinase resistant penicillin : MSSA, streptococci Aminopenicillins : streptococci, enterococci Carboxy and ureido penicillins : Pseudomonas aeruginosa , streptococci, enterococci

6. FORMS Pencillin V: oral solution tablets 250mg and 500 mg Penicillin G: Injectable 1 million units per 50 ml(aqueous) ; 600,000 units per 1 ml syringe(procaine)

7. INDICATIONS Syphilis- Benzathine Penicillin Gonorrhea Streptococcal infections Pneumococcal infections Meningococcal infections Diphtheria Prophylaxis: Rheumatic fever,

8. Syphilis For early syphilis(primary , secondary and early latent syphilis( <2 years): Benzathine penicillin G 2.4megaunits IM single dose For late syphilis(>2 years duration ): Benzathine penicillin 2.4 megaunits IM weekly for 3 weeks For neurosyphilis : Aqueous crystalline penicillin G 3-4 megaunits IV every 4 hourly for 10-14 days

9. Rheumatic fever(RF) prophylaxis Benzathine penicillin 1.2 MU IM 3 weekly or Oral penicillin V 250 mg BD

10. Adverse effects Rashes Allergy Seizures Encephalopathy Leucopenia, thrombocytopenia and coagulation deficiencies

11. AMINOPENCILLIN (Category B) AMPICILLIN Food interfere with absorption Oral absorption incomplete but adequate ADR: diarrhea frequent, rashes, hypersensitivity reaction. Interferes with deconjugation and enterohepatic circulation Dose: oral 250- 500mg x 6hrly iv or im 1-2 g x 4/6 hrly B lactamase inhibitor: salbactum AMOXICILLIN Food doesn’t interfere absorption ADR: same but diarrhea is less Dose : 500 mgX POX 8hrly B lactamase inhibitor: clavulonic acid

12. INDICATIONS Urinary tract infections Gonorrhea- Ampicillin 3.5g + Probenecid 1g Premature rupture of membrane Mastitis: dicloxacillin Respiratory tract infections Meningitis Cholecystitis Subacute Bacterial Endocarditis - Ampicillin 2g i.v . 6 hourly H. Pylori Septicemia and mixed infections

13. URINARY TRACT INFECTION Asymptomatic Bacteriuria 3-7 days treatment with Amoxicillin 500 mg x tds OR Ampicillin 250 mg x qid OR Nitrofurantoin 50-100 mg x qid Pyelonephritis 21 days treatment with above drugs

14. For respiratory tract infections Ampicillin: 250mg iv qid Amoxicillin: 500mg oral tds for 10- 14 days For prelabour rupture of membrane Inj. Ampicillin 1 g IV stat followed by 500 mg IV QID

15. Prophylactic antibiotic for bacterial endocarditis Antibiotic prophylaxis during labor and 48 hours after delivery is considered appropriate Iv ampicillin 2g and gentamicin 1.5 mg/kg(not exceeding 120 mg ) High risk patients are: Structural heart disease Rheumatic heart disease Cyanotic congenital heart disease presense of dental and respiratory tract infection genitourinary procedures and catheterization prosthetic heart valves Prior history of infective endocarditis cardiac transplant