30 Questions
What can interfere with the absorption of quinolones?
Dairy products, antacids, iron, zinc, or calcium supplements
What is the effect of sulfamethoxazole on the gut flora?
It increases the growth of Clostridium difficile
What is a common side effect of sulfonamides?
All of the above
Why should sulfonamides be used with caution in patients with G6PD deficiency?
Because of the risk of haemolysis
What is a precaution to be taken when using sulfamethoxazole in patients with renal impairment?
Reduce the dose of sulfamethoxazole
What is a contraindication for the use of sulfonamides?
Preterm infants and neonates
What is a characteristic of sulfonamide allergy?
Both anaphylaxis and Stevens-Johnson syndrome
What is a precaution to consider when co-administering tetracyclines with oral retinoids?
Increased risk of benign intracranial hypertension
Which of the following is a contraindication for aminoglycoside use?
History of treatment with ototoxic or nephrotoxic drugs
What is a common adverse reaction associated with quinolone use?
Rash
Which of the following is a precaution to consider when using quinolones in the elderly?
Increased risk of tendon damage
What is a contraindication for quinolone use in children?
Use is not recommended except in severe infections where benefit outweighs the risk of arthropathy
What is the result of an acid and base reaction in the context of antibiotics?
Salt formation
Which of the following antibiotics is not a beta-lactam antibiotic?
Aminoglycosides
What is a precaution to consider when co-administering aminoglycosides with neuromuscular blockers?
Increased risk of neuromuscular blockade
What is a precaution to consider when using tetracyclines in patients with hepatic impairment?
Hepatotoxicity is more likely
What is the estimated percentage of people who may experience cross-reactivity between penicillins, cephalosporins, and carbapenems?
5-10%
What is the main concern with the parenteral dosage form of Benzylpenicillin sodium?
High sodium content
What type of immune response is involved in severe skin rashes caused by penicillins?
B-cell mediated response
Why are all penicillins considered safe during pregnancy?
Because they are pumped into the renal tubule and eliminated
What is the estimated percentage of people who experience a rash as a side effect of penicillin allergy?
5-10%
What is the reason for reduced distribution of glycopeptides?
Due to their low water solubility
What is the name of the condition that occurs due to rapid infusion of vancomycin?
Red man syndrome
What is the mechanism of action of beta-lactam antibiotics?
Inhibit cell wall formation by inhibiting transpeptidase
What is the name of the enzyme that breaks down beta-lactam antibiotics?
Beta-lactamase
What is the name of the bacterium that is resistant to vancomycin?
VRSA
What is the name of the aminoglycoside that is known for its ototoxicity?
Gentamycin
What is the name of the glycopeptide that is commonly used in medical practice?
Vancomycin
What is the mechanism of action of glycopeptides?
Inhibit cell wall formation by binding to peptidoglycan
What is the name of the side effect that occurs due to the accumulation of aminoglycosides in the ears?
Ototoxicity
Study Notes
Quinolone Drug Interactions
- Dairy products, antacids, iron, zinc, or calcium supplements may interfere with the absorption of quinolones, so they should not be taken within 2 hours of a quinolone dose.
- Quinolones may increase the effects of caffeine, so caffeine intake may need to be reduced.
- Ciprofloxacin is an inhibitor of CYP3A4.
- Gatifloxacin and moxifloxacin do not appear to interact with hepatically metabolized drugs (e.g., theophylline, caffeine, warfarin).
Folate Inhibitors
- Trimethoprim and sulfamethoxazole are used in combination for synergistic effect.
- Adverse drug reactions (ADRs) of folate inhibitors include fever, nausea, vomiting, diarrhea, anorexia, rash, itch, sore mouth, hyperkalaemia, and thrombocytopenia.
- Rare ADRs include megaloblastic anaemia, methaemoglobinaemia, erythema, hypoglycaemia, hepatitis, crystalluria, urinary obstruction with anuria/oliguria, lowered mental acuity, depression, tremor, ataxia, Clostridium difficile-associated disease, and aseptic meningitis.
Sulfonamide Allergy
- Sulfonamide allergy, also known as "sulfur allergy," is caused by the arylamine-sulfonamide functional groups.
- Symptoms include fever, dyspnoea, cough, rash, eosinophilia, anaphylaxis, Stevens-Johnson syndrome, toxic epidermal necrolysis, serum sickness-like syndrome, lupus-like syndrome, pneumonitis, hepatitis, interstitial nephritis, systemic vasculitis, and pancytopenia.
- Cross-sensitivity between sulfonamides and related drugs (e.g., sulfonylureas, thiazides diuretics, frusemide, celecoxib) may occur.
Folate Inhibitor Precautions
- G6PD deficiency increases the risk of haemolysis with sulfonamides.
- Slow acetylator phenotype increases the risk of adverse effects with sulfonamides.
- Low urine pH increases the risk of crystalluria, and sulfamethoxazole is poorly soluble at low pH.
- Drugs that cause potassium retention (e.g., ACE inhibitors) may contribute to hyperkalaemia with TMP.
- Renal impairment increases the risk of hyperkalaemia or hypoglycaemia, and the dose of sulfamethoxazole should be reduced.
- Folate inhibitors are contraindicated in preterm infants and neonates.
Tetracycline Precautions
- Tetracyclines are contraindicated in children and pregnant women due to the risk of tooth discoloration and bone growth inhibition.
- Tetracyclines may increase the risk of benign intracranial hypertension with oral retinoids (e.g., isotretinoin, acitretin).
- Hepatic impairment increases the risk of hepatotoxicity with tetracyclines.
- Doxycycline and minocycline can be used with dose adjustment in renal impairment.
Aminoglycoside Precautions
- Aminoglycoside allergy, ototoxicity, and nephrotoxicity are increased in patients with a history of treatment with ototoxic or nephrotoxic drugs.
- Neuromuscular disease (e.g., myasthenia gravis) increases the risk of neuromuscular blockade with aminoglycosides.
- Hypocalcaemia, hypermagnesaemia, general anaesthesia, and large transfusions of citrated blood increase the risk of aminoglycoside toxicity.
- Dehydration increases the risk of toxicity, and renal impairment increases the risk of nephrotoxicity and ototoxicity.
Quinolone Precautions
- Quinolones are contraindicated in children and adolescents due to the risk of arthropathy.
- Quinolones may increase the risk of seizures in patients with epilepsy or a history of CNS disorders.
- Treatment with bupropion should be avoided due to the increased risk of seizures.
- Myasthenia gravis increases the risk of exacerbation with quinolones.
- G6PD deficiency increases the risk of haemolytic anaemia with quinolones.
- Prior or concomitant use of corticosteroids increases the risk of tendon damage with quinolones.
Quinolone ADRs
- Common ADRs include rash, itch, nausea, vomiting, diarrhea, abdominal pain, headache, dizziness, insomnia, depression, restlessness, tremors, arthralgia, arthritis, myalgia, tendonitis, crystalluria, and interstitial nephritis.
- Infrequent ADRs include hypoglycaemia, hyperglycaemia, blood dyscrasias, seizures, psychotic reactions, angioedema, anaphylaxis, pseudomembranous colitis, tendon rupture, Stevens-Johnson syndrome, hepatitis, peripheral neuropathy, and others.
This quiz covers the interactions of quinolone drugs with other substances, including dairy products, antacids, and caffeine. It also discusses the effects of quinolones on hepatically metabolized drugs.
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