Antibiotics: Aminoglycosides - Gentamicin

Aminoglycosides - Gentamicin

• Bactericidal agent effective against serious Gram-negative aerobic bacilli infections.
• Mechanism: Inhibits protein synthesis and irreversibly binds to bacterial ribosomes, causing misreading of genetic code and cell death.
• Indicated for pseudomonas and various other Gram-negative infections.
• Administration: IM or IV route with rapid onset; peak effect occurs within 30-90 mins and half-life of 2-3 hours, metabolized in the liver.
• Contraindications include known allergies, renal/hepatic disease, hearing loss, active herpes/mycobacterial infections, and specific neuromuscular conditions.
• Use caution in pregnancy; frequent urine function tests are necessary due to kidney excretion.
• High risk of nephrotoxicity and ototoxicity; use amikacin only if essential.
• Adverse effects include sinusitis, dizziness, rash, fever, and potential nephrotoxicity.
• Drug interactions: Synergistic with penicillins/cephalosporins; avoid potent diuretics and certain anesthetics to prevent increased neuromuscular blockade.

Carbapenems - Ertapenem

• Bactericidal antibiotic targeting cell membrane synthesis in susceptible bacteria.
• Used for community-acquired pneumonia, complex GU and intra-abdominal infections, and skin infections.
• Administered IV/IM once daily; rapid onset with peak in 30-120 mins, half-life of 4 hours, and excreted unchanged in urine.
• Contraindications include known allergies, seizure disorders, and meningitis; caution in pregnancy and renal function monitoring is essential.
• Adverse effects may include headache, dizziness, nausea, vomiting, pseudomembranous colitis, and injection site pain.
• Careful consideration required when used alongside valproic acid to avoid decreased serum levels and increased seizure risk.

Cephalosporins - Cefaclor

• Inhibits bacterial cell wall synthesis resulting in cell death.
• Indicated for respiratory infections, UTIs, otitis media, and typhoid fever.
• Administered orally; peak effect achieved in 20-60 mins, duration of action is 8-10 hours, half-life of 30-60 mins.
• Contraindications include allergies to cephalosporins/penicillins due to cross-sensitivity; caution advised for liver or kidney impairment and in pregnancy/lactation.
• Possible adverse effects include nausea, vomiting, diarrhea, rash, and risk of colitis.
• Drug interactions: Increased nephrotoxicity risk when used with aminoglycosides, and can enhance anticoagulant effects leading to bleeding.

Fluoroquinolones - Ciprofloxacin

• Disrupts DNA replication in Gram-negative bacteria, inhibiting cell reproduction.
• Treats respiratory, dermatological infections, typhoid fever, and post-anthrax exposure.
• Available orally and IV; peak effect varies (60-90 mins orally; 30 mins IV) with half-life of 3.5-4 hours.
• Contraindications include allergy to the drug, pregnancy, and renal dysfunction.
• Adverse effects include headache, dizziness, nausea, hypotension, and rash.
• Drug interactions: Reduced effectiveness with certain antacids and supplements; caution with drugs that increase QTc interval and parenteral penicillins.

Sulfonamides - Cotrimoxazole

• Inhibits two consecutive steps in protein and nucleic acid synthesis, preventing cellular multiplication.
• Indicated for UTIs and pneumonia caused by susceptible strains.
• Combination of sulfamethoxazole and trimethoprim administered orally; rapidly absorbed, peak effect in 1-4 hrs.
• Contraindications: Allergies to sulfonamides, pregnancy, and certain diuretics; caution in patients with renal disease.
• Adverse effects include gastrointestinal disturbances, bone marrow suppression, and skin reactions.
• Drug interactions: Increased hypoglycemia risk with antidiabetic medications and nephrotoxic risk when combined with cyclosporine.

Tetracycline

• Inhibits protein synthesis in bacteria, potentially toxic at high concentrations.
• Caution advised in pregnancy; safer alternatives may include isoniazid.
• Adverse effects include peripheral neuropathy, gastrointestinal issues, and liver toxicity.
• Drug interactions: Increased liver toxicity risk when combined with certain antibiotics; decreased effectiveness when combined with rifampin or rifabutin.

Ketolides - Telithromycin

• Binds bacterial ribosomes altering protein function, leading to cell death.
• Effective against resistant strains of bacteria; approved for community-acquired pneumonia treatment.
• Administered orally with rapid onset; peak at 0.5-4 hours and half-life of 10 hours.
• Contraindications include allergies and known prolonged QT interval or certain arrhythmias; use caution in liver/kidney impairments.
• Adverse effects: Headache, dizziness, gastrointestinal disturbances, and superinfections.
• Drug interactions: Avoid with certain statins and antiarrhythmics due to risk of serious adverse effects.

This quiz focuses on the antibiotic Gentamicin, a bactericidal agent effective against serious infections caused by Gram-negative bacteria. It explores therapeutic actions, pharmacokinetics, and the specific indications for use, including pseudomonas infections.