20 Questions
What is the alternative to 3rd generation cephalosporin in treating bacterial meningitis?
Chloramphenicol
What is the effect of calcium on the absorption of tetracyclines?
Decreases absorption
What is the primary route of elimination of doxycycline?
Biliary excretion
Why are tetracyclines contraindicated in children under 8 years old?
Risk of deposition in the bone and teeth
What is the effect of taking tetracyclines with milk products?
Decreases absorption
Which of the following is NOT a contraindication for tetracyclines?
Adults over 60 years old
What is the primary mechanism of adverse effect of chloramphenicol in patients with low levels of G6PD?
Hemolytic anemia
What is the primary route of elimination of chloramphenicol from the body?
Hepatic conjugation with glucuronide
What is the advantage of using doxycycline in specific infections?
It has a long half-life
Why is the use of chloramphenicol limited?
It can cause aplastic anemia
What is the primary reason why clindamycin and broad-spectrum antimicrobials may induce pseudomembraneous colitis?
They disrupt the gut flora
Which of the following antibiotics is a protein synthesis inhibitor?
All of the above
What is the primary characteristic of chloramphenicol absorption?
Complete oral absorption
What is the primary distribution characteristic of chloramphenicol?
Widespread tissue distribution
What is the primary organ responsible for the elimination of macrolides?
Liver
Which of the following macrolides is not an inhibitor of the liver microsomal enzyme system?
Azithromycin
What is the main reason for contraindicating macrolides in patients with hepatic dysfunction?
Risk of hepatotoxicity
Which of the following is a characteristic of azithromycin's pharmacokinetics?
Long half-life
What is the main adverse effect of clindamycin?
Pseudomembranous colitis
What is the main indication for the use of clindamycin?
Anaerobic infections
Study Notes
Protein Synthesis Inhibitors
Chloramphenicol
- Adverse effects: gastrointestinal disturbance, diarrhea, hemolytic anemia, aplastic anemia, and gray baby syndrome
- Risk of drug interactions: inhibits liver microsomal enzymes (LME)
- Pharmacokinetics: lipophilic, completely absorbed orally, widely distributed, and eliminated through liver conjugation with glucuronide and renal tubule secretion
- Uses: restricted due to toxicity, but used for bacterial meningitis, anaerobic brain abscess, typhoid fever, and eye infections
Tetracyclines
- Broad spectrum antibiotics effective against Mycoplasma pneumonia, Chlamydia, Rickettsia, and Gram +ve and -ve bacteria
- Examples: doxycycline, minocycline
- Pharmacokinetics: incompletely absorbed orally, decreased by Ca2+, iron, antacids, and dairy products, and eliminated through metabolism, glucuronidation, and renal excretion
- Adverse effects: gastric discomfort, GIT disturbance, diarrhea, deposition in bone and primary dentition, hepatotoxicity, and phototoxicity
- Contraindications: renally impaired patients, pregnant or breastfeeding women, and children under 8 years old
Macrolides
- Effective against atypical pneumonia, Mycoplasma pneumonia, and Chlamydia
- Examples: erythromycin, clarithromycin, and azithromycin
- Pharmacokinetics: absorption decreased by food, concentrated in the liver, and eliminated through liver metabolism
- Adverse effects: epigastric pain, hepatotoxicity, and ototoxicity
- Contraindications: patients with hepatic dysfunction, and those with drug interactions due to LME inhibition
Clindamycin
- Used for anaerobic bacteria, bone infections, and beta-lactamase producing organisms
- Adverse effects: pseudomembranous colitis caused by overgrowth of C. difficile, treated with oral metronidazole or vancomycin
This quiz covers the pharmacology of chemotherapy, focusing on protein synthesis inhibitors, hepatotoxic antimicrobials, and pediatric considerations.
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