Antimicrobials

Question 1

name the S/E of tetracyclines

Answer 1

epigastric distress (to drink plenty of fluids and avoid administration just before bed time), brown-yellow discolouration of teeth (+/- enamel hypoplasia, temporary stunting of growth) in children <8yo, photosensitivity +/- severe sunburn , superinfection with prolonged usage (CDAD when use > 2 months, oral thrush), nephrotoxicity and hepatotoxicity, vestibular dysfunction with tinnitus/ dizziness/vertigo (esp. for minocycline)

Question 2

name the drug interactions for tetracyclines

Answer 2

trivalent/divalent cation containing products, incl. antacids and dairy products (reduce tetracyclines absorption), oral SU (hypoglycemia), digoxin / lithium / theophylline (toxicity), warfarin (bleeding), oral contraceptives (reduces its efficacy), penicillins (reduce its efficacy)

Question 3

name the contraindications for tetracyclines

Answer 3

pregnancy (category D), lactation, children <8yo

Question 4

name the S/E of aminoglycosides

Answer 4

ototoxicity (vestibular and auditory; elderly more susceptible and deafness may be irreversible), nephrotoxicity (elderly more susceptible), neuromuscular paralysis, hypersensitivity (rash + contact dermatitis for topically applied neomycin)

Question 5

name the contraindications for aminoglycosides

Answer 5

renal impairment, hearing impairment, myasthenia gravis, pregnancy (category D), concomitant use with other nephrotoxic / ototoxic / neuromuscular blocking agnets, intestinal obstruction/ulcerative gastrointestinal disease (for neomycin only)

Question 5

name the S/E of macrolides

Answer 5

gastric distress (more with erythromycin than clarithromycin and azithromycin), QTc prolongation, ototoxicity (high IV doses of erythromycin has been associated with transient deafness and azithromycin has been associated with irreversible hearing loss), hepatotoxicity (cholestatic jaundice)

Question 6

name the contraindications of macrolides

Answer 6

use with caution in patients who have pro-arrythmic conditions, and hepatic dysfunction

Question 7

name the drug interactions of macrolides

Answer 7

CYP450 inhibitor, thus potentiates the effect of digoxin, corticosteroids, warfarin (erythromycin and clarithromycin only)

Question 8

name the S/E of clindamycin

Answer 8

gastric distress / vomiting / diarrhoea, skin rashes, CDAD (as C. difficile is alw resistant to clindamycin)

Question 9

name the contraindications of clindamycin

Answer 9

patients with pseudomembranous colitis / ulcerative colitis

Question 10

name the S/E of linezolid

Answer 10

bone marrow suppression, incl. thrombocytopenia for prolonged use (>10 days), serotonin syndrome (due to linezolid’s non-selective monamine oxidase inhibitory activity; may be precipitated by SSRI, MAOi, tyramine rich foods), gastrointestinal effects incl. nausea and diarrhoea, irreversible peripheral neuropathy and optic neuritis (causing blindness)

Question 11

name the drug interactions of linezolid

Answer 11

contraindicated within 2 weeks use of MAOi, avoid concurrent administration with SSRI and avoid tyramine rich foods

Question 11

name the S/E of fluoroquinolones

Answer 11

gastric distress incl. N/V/D, headache/lightheadedness/dizziness, dysglycemia, tendonitis/tendon rupture, aortic dissection/aortic aneurysm rupture, arthropathy in children <18yo, peripheral neuropathy, QTc prolongation, photosensitivity, increased risk of CDAD esp with ciprofloxacin

Question 12

name the contraindications of fluoroquinolones

Answer 12

caution in patients with diabetes, elderly, CNS disorders e.g. epilepsy, aortic blockages / aneurysms / HTN / blood vessel disorders, patients with myasethensia gravis, pro-arrhythmic conditions, pregnancy, lactation, children <18yo, G6PD deficiency

Question 13

name the drug interactions of fluoroquinolones

Answer 13

CYP450 inhibitor, hence potentiates the effects of cyclosporines, warfarin, digoxin, corticosteroids; avoid administration with polyvalent cations

Question 14

name the S/E of co-trimoxazole

Answer 14

hypersensitivity from rash to angioedema and SJS, crystalluria +/- nephrotoxicity, N/V hence to take after food, photosensitivity, myelosupression due to folate acid deficiency (anemia, leukopenia, granulocytopenia, thrombocytopenia), hyperkalemia, hepatotoxicity

Question 15

name the contraindications of co-trimoxazole

Answer 15

avoid in patients with hx of hypersensitivity to sulfa drugs, patients with folic acid deficiency, first / last trimester of pregnancy / when at term (due to folate acid deficiency + kernicterus), lactation (due to kernicterus), in infants <2 months old (due to kernicterus), avoid in G6PD deficiency

Question 16

name the S/E of nitrofurantoin

Answer 16

hypersensitivity incl. fever and chills, gastric distress incl. N/V/D hence to take after food (also increases absorption), colours urine brown, headache, pulmonary toxicity (pulmonary fibrosis), hepatotoxicity (cholestatic jaundice and hepatocellular damage) and /or neuropathy (elderly are more susceptible, esp. if poor renal function and prolonged treatment duration), hemolytic anemia and other hematopoietic disturbances in patients with G6PD deficiency

Question 17

name the contraindications of nitrofurantoin

Answer 17

patients with severe renal impairment (CrCL <30mL/min), G6PD deficiency, last trimester of pregnancy / at term / lactation / infant <2 months old (G6PD of infant unknown)

Question 18

name the S/E of metronidazole

Answer 18

gastric distress incl. N/V/abdominal cramps, epigastric distress, metallic taste in mouth, oral yeast infection, nervous system effects incl. convulsive seizures, optic neuropathy, peripheral neuropathy (rare but neccesitates discontinuation of drug; to avoid alcohol)

Question 19

name the contraindications of metronidazole

Answer 19

caution in severe hepatic dysfunction, avoid in first trimester of pregnancy (but category B for pregnancy)

Question 20

name the S/E of penicillins

Answer 20

hypersensitivity, GI symptoms (N/V, CDAD), neurotoxicity (convulsions and coma)

Question 21

name the S/E of cephalosporins

Answer 21

hypersensitivity, GI symptoms (V/D, CDAD)

Question 22

name the S/E of carbapenems

Answer 22

hypersensitivity, GI symptoms (V/D, CDAD), neurotoxicity (seizures at high IV doses & in renally impaired)

Question 23

name the S/E of aztreonam

Answer 23

generally well tolerated, but can cause occasional skin rashes and elevated transaminases

Question 24

name the S/E of vancomycin

Answer 24

thrombophlebitis with fever and chills, red man syndrome +/- hypotension (can be prevented by prolonging infusion duration to 1-2h), nephrotoxicity, ototoxicity