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2010-11-17 12:42:02
Pharm Exam antibiotics antifungals

Pharm Exam 4, pt 4: antibiotics and antifungals
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  1. Drug/bug pair: Nafcillin (a PCN)
    treats: MMSA (methicillin sensitive staphylococcus aureus)
  2. Drug/bug pair: Amoxicillin (an aminopenicillin)
    treats: H. influenzae
  3. Drug/bug pair: Piperacillin (a ureidopenicillin)
    treats: pseudomonas
  4. What drugs act against cell walls?
    Penicillins and cephalosporins. (both have beta-lactam groups)
  5. When should a pt's allergies be assessed?
    Before ever administration of antibiotics/antifungals.
  6. What penicillins should ONLY be given IM?
    Procain penicillin and benzathine penicillin.
  7. Important facts about hypersensitivity reactions.
    • Non-dose related (aka allergy)
    • closely monitor for 15-30 min after initial dose of PCNs, esp for rash/urticaria
    • thrombocytopenia may occur
  8. Important facts about direct tissue toxicity.
    • Dose related (can occur to anyone if dose is high enough).
    • Monitor for twitching/seizures (often seen in pts who receive large doses of anti-pseudomonal PCNs who can't eliminate drug)
    • High doses may decrease ability of platelets to function properly resulting in bleeding tendencies (count is normal)
    • Procaine PCN may cause acute psychotic rxns.
  9. Patient related variables important to PCNs
    • allergy to PCN or cephalosporin
    • renal dysfunction
  10. Which generations of cephalosporins work against pseudomonas?
    Third (only ceftazidime) and fourth generations.
  11. What are common clinical uses of cephalosporins?
    • - most community-aquired and nosocomial infections (due to wide range of activity)
    • - CNS infections (3rd and 4th gens only)
    • - skin infections (1st gen esp)
  12. Toxicity concerns related to cephalosporins.
    • - hypersensitivity/allergic reactions (non-dose related) - approach is same as for PCNs (monitor for rash/urticaria 15-30 min)
    • - direct tissue toxicity (dose related) - same as PCNs (twitching/seizures/poor platelet function)
  13. Administration considerations for cephalosporins.
    • - assess for allergy prior to administration
    • - monitor for phlebitis at site of injection
  14. What antibiotic should be considered for hightly resistant organisms or pts at risk for highly resistant organisms?
    • Carbapenems.
    • Broad spectrum: gram +/-, anerobes
    • No atypical coverage (mycoplasma, Legionella, chlamydia)
  15. Toxicities of Carbapenems.
    seizures (decrease seizure threshold)
  16. Drug/bug pair: azithromycin
    treats: mycoplasma (an atypical)
  17. What are atypical organisms?
    mycoplasma, Legionella, and Chlamydia pneumonia
  18. What drugs are macrolides?
    erythromycin, clarithromycin, and azithromycin
  19. Drug/bug pair: azithromycin
    treats: Chlamydia (and mycoplasma)

    better than Doxycyclin because of short course of treatment (despite increased cost)
  20. Toxicities of macrolides (eryth, clarith, and azith)
    • primarily dose related
    • GI - D/N/abdominal pain (esp with eryth)
    • prolongation of QT interval (less with azith)
  21. Drug interactions with macrolids (eryth, clarith, azith)
    Theophylline, carbamazepine, cyclosporine (clearance is reduced due to interaction with p450 enzyme).
  22. Drugs that are fluoroquinolones.
    ciprofloxacin and levofloxacin

    - cover all atypicals (Legionella, chlamydia, mycoplasma)
  23. Toxicities of fluoroquinolones.
    • - cartilege damage in beagles, not recommended in children (except cipro for tx of gonorrhea in adolescents)
    • - tendonitis and tendon rupture (stop drug if pain develops)
    • - decreased seizure threshold
  24. Trimethoprim plus sulfamethoxazole
    • aka bactrim (a sulfonamide)
    • treats: otitis media when ampicillin resistant influenza is suspected; community and hospital aquired infections, good MRSA activity
    • does not treat streptococcal (no coverage)
  25. Drug/bug pair: trimethoprim plus sulfamethoxazole (bactrim)
    treats: pneumocystis carinii (PCP)
  26. Administration consideration for sulfonamides.
    • - maintain adequate fluid intake to prevent crystaluria
    • - displacement of bilirubin may lead to kernicterus in newborns (avoid use in pregnacy/breastfeeding/infants <6wks)
  27. Toxicities of trimethoprim (in bactrim)
    • megaloblastic anemia (sx of folic acid deficiency); treat with folinic acid
    • hyperkalemia and renal insufficiency (esp when treating PCP)
  28. Drug/bug pair: metronidazole (flagyl)
    treats: c.diff (and trichomoniasis)
  29. Drug/bug pair: metronidazole (flagyl)
    treats: trichomoniasis (and c.dif)
  30. Administration considerations for metronidazole:
    Do not infuse iwht other IV drugs if possible.
  31. Toxicities of metronidazole:
    • nausea
    • antabuse-like effects (inhibits alcohol dehydrogenase)
    • interacts with warfarin
  32. Drug/bug pair: clindamycin
    Staph (including MRSA)
  33. Toxicities of clindamycin.
    Psudomembranous colitis: diarrhea involving superinfections of C.dif which produces a toxin. Treat wiht oral metronidazole or vancomycin.
  34. Aminoglycosides
    • ex. gentamycin
    • used for wide range of aerobic gram-neg organims (serious, usually nosocomial)
    • poorly absorbed orally
  35. Toxicities of aminoglycosides:
    • - nephrotoxicity (monitor serum creatinine)
    • - ototoxicity (cochlear or vestibular)
  36. Drug/bug pair: vancomycin
    treats: MRSA - methacillin resistant staph aureus
  37. Administration considerations for vancomycin.
    • Not absorbed orally (oral therapy only effective for c.diff colitis)
    • Give IV doses slowly to avoid hypotension.
    • IM route causes tissue necrosis.
  38. Toxicities related to vancomycin.
    • Nephrotoxicity (at concentrations >20mg/dl)
    • phlebitis
    • red man's syndrom (histamine rxn to too fast administration, prevent w/benadryl)

    monitor troughs (correlate to efficacy and toxicity)
  39. Tetracyclines
    • treats: STIs (gonorrhea, syphilis) and acne
    • give with full glass of water
    • dairy/iron/antacids decrease absorption
    • may have dental effects in children (do not use for <8y/o)
  40. Chloramphenicol
    • antibiotic
    • treats: salmonella, PID/chlamydia
    • be very careful with dose
    • monitor for blood dyscrasias: RBC then WBC then platelets decrease
  41. Drug/bug pair: Linezolid
    • treats: VRE
    • given IV/PO