(精选)β-内酰胺类抗生素(英文课件)β-lactam antibiotics教学课件.pptVIP

Clinical uses Mixed aerobic and anaerobic infections Carbapenem is the β lactam of choice for treatment of enterobacter infections. Pseudomonal infections Intraabdominal infections Febrile neutropenic patient Septicaemia. Meropenem Similar to imipenem but it is highly active against gram-negative aerobes . Not degraded by renal dehydropeptidase Adverse effects Nausea,vomiting,diarrhea Skin rash and reaction at the site of infusion High dose with imipenem in renal failure cause seizure Patients allergic to penicillin may be allergic to carbapenems . Monobactams Aztronam Active only against gram-negative aerobic bacteria. Given I.V. Similar to β-lactam in mechanism of action and adverse effects. Macrolides(MACROCYCLIC LACTONE RING 14-16 ATOMS) Erythromycin(14 atom lactone ring ) Is effective against Legionella,cornybacteria,gram-positive cocci,chlamydia,helicobacter Less effective on gram-negative organisms. Mechanism of action Inhibit protein synthesis via binding to 50 S ribosomal RNA subunit. Bactericidal at high conc.and bacteriostatic at low conc. Pharmacokinetics Destroyed by stomach acid and must be administered with enteric coating . Food interferes with absorption Half-life 1.5h Excreted mainly through bile,5%only in urine. Cross placenta not B.B.B. Clinical uses Drug of choice of corynebacterial infections Chlamydial infections Community acquired pneumonia Mycoplasma Legionella Penicillin allergic patients. Adverse effects Anorexia,nausea,vomiting,diarrhea. Liver toxicity especially with the estolate coat produce acute cholestatic hepatitis Drug interactions as it is cytochrome p450 inhibitor. Hypersensitivity reactions . Clarithromycin(14 atom lactone ring) Acid stable Mechanism of action as erythromycin Spectrum as erythromycin but more active against Mycobacterium avium complex.m.leprae.Toxoplasma gondii. Half –life 6h. Metabolised in liver (active metabolites ). Partially excreted in urine Drug interactions similar to erythromycin Has a lower fr