Pharm Exam 2

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Pharm Exam 2
2011-10-04 05:42:59
Immune System Anti infectives Antiretrovirals

Antibiotics and Antivirals required for Exam 2
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  1. Chemotherapy
    Using drugs to fight agents
  2. selective toxicity
    • toxic only to targeted microbe
    • not toxic to host
  3. narrow spectrum antibiotic
    • very specific antibiotic
    • fights just certain bacteria
  4. broad spectrum antibiotic
    • not specific
    • fights a wide variety of bacteria
  5. Gram neg bacteria
    Has an outer membrane
  6. classification of antibiotics
    drugs work on:
    • cell wall synthesis
    • cell membrane permeability
    • protein synthesis
    • synthesis of nucleic acids
    • antimetabolites (disrupts metabolism rxns)
    • viral enzyme inhibitors
  7. Antibiotic Resistance
    • Result of overuse of antibiotics
    • Spontaneous mutation
    • Conjugation: transfer of resistance factors between bacteria
    • Food and animal industry
  8. Conjugation
    • Transfer of extrachromosomal DNA is transferred from one bacterium to another.
    • Need 2 DNA strands: one codes for resistance + one which codes for DNA transfer=R factor
    • The donor transfer the resistance gene (s) to another
    • Primarily seen among Gram neg bacteria
    • Normal flora can transfer resistance to pathogens
    • Frequently confers multiple drug resistance
  9. Resistant forms of Staphylococcus aureus & Staphylococcus epidermis
    • Methicillin-resistant S. aureus (MRSA)
    • Methicillin-resistan S. epidermis (MRSE)
    • Tx: vancomycin (Vancocin)
  10. Combination therapy cont.
    • Additive: sum of the effects of each drug
    • Potentiative: (synergistic) The effect is greater than the sum of the parts
    • Antagonistic: usually seen when a bactericidal and a bacteriostatic drug are given together. Bactericidal drugs usually work only against actively growing microbes. If the bacteriostatic has suppressed growth, bactericidal job doesnt work well.
  11. Suprainfections/Superinfections
    • Secondary infection
    • Caused by opportunistic infection resistant to current abx tx
    • Normal flora keep each other in check.
    • Sometimes abx kill off good bacteria, other bacteria which may be drug resistant flourish
  12. Suprainfection: C. diff
    • Antibiotic associated colitis
    • Caused by a toxin from C. diff growth following antibiotics (e.g., ampicillin, cephalosporins, clindamycin)
    • S/S: fever, abd cramping, watery diarrhea, blood or mucous in stools
    • Tx: metronidazole (Flagyl) PO or vancomycin (Vancocin) PO
    • Very sick patients
    • Tough to treat
    • Long course
  13. Combination therapy
    • Used for complicated or sever infection
    • Synergy-increased effect
    • Prevents resistance (but could lead to increased resistance)
    • Ex: treatment for TB
  14. Indications for Antibiotic combinations
    • Initial therapy for a severe infection
    • Mixed infections
    • prevention of resistance
    • decreased toxicity
    • enhanced antibacterial action
  15. Prophylactic use
    • Surgery (cardiac, abdominal)
    • Bacterial endocarditis (often treated before dental procedures)
    • Patients that are immunosuppressed (HIV+, neutropenia (low white cell count), recurrent UTI)
  16. Misuse of antibiotics
    • Untreatable infection
    • Fever of unknown origin
    • Improper dosage
    • Lack of ID of organism
    • Omission of surgical drain
  17. Nursing implications
    • Assess s/s of infection
    • Obtain history of sensitivity
    • Observe for anaphylaxis
    • Culture and sensitivity before first dose
    • Administer ATC (around the clock=before bed, when you get up, 8 hrs later)
  18. culture & sensitivity (C/S)
    • Get sample from wound
    • Lab grows bacteria and treats with several antibiotics
    • Give general antibiotics while waiting for cultures to grow
    • Treat with specific antibiotic
  19. Penicillins
    • Weaken bacterial cell wall
    • Have beta lactam ring
    • Weaken cell wall, causing up take of excessive water and rupture
    • Bactericidal
    • Bacterial resistance: inability of penicillins to reach their target (particularly in gram neg bacteria); inactivation of penicillins by bacterial enzymes
  20. Penicillinases (Beta-Lactamases)
    • Enzymes that render penicillins and other b-l abx inactive
    • Penicillins are combined with beta-lactamase inhibitors: antimicrobial spectrum is extended
  21. Beta lactamase inhibitors
    inhibits beta lactamase
  22. Beta lactamase inhibitors (examples)
    • Clavulanic acid
    • Sulbactam
  23. Penicillin G (Benzylpenicillin)
    Allergy: penicillins are the most common cause of drug allergies
  24. Penicillinase-resistant penicillin
    nafcillin (Unipen)
  25. Broad spectrum penicillins (aminopenicillins)
    • aminopenicillin: amoxicillin (Amoxil)
    • beta-lactamase: ampicillan/sulbactam (Unasyn), amoxicillin/clavulanate (Augmentin)
    • Adverse effects: rash, diarrhea
  26. Extended spectrum penicillins (antipseudomonal penicillins)
    Beta-lactamase: ticarcillin clavulanate (Timentin)
  27. Penicillin ADRs
    Allergy: Anaphylaxsis, diarrhea, rash (most common)
  28. Penicillin allergy tx
    • Epinephrine
    • Corticosteroids
    • Antihistamines
    • Respiratory support
  29. Penicillins (interactions)
    • Probenecid-used with gonorrhea; inhibits excretion in kidneys of penicillin resulting in higher conc
    • Do not admix (same IV bag) pen & aminoglycosides (e.g., tobramycin, gentamycin)
    • Oral contraceptives-my decrease efficacy of oral contraceptives (e.g., ampicillin)
  30. Cephalosporins
    • Most widely used antibiotics
    • Beta lactam antibiotics
    • Similar to penicillin in structure
    • Bactericidal
    • Usually given parenterally (poor PO absorption)
  31. Cephalosporins - ADR
    • Allergy (linked to penicillin allergy, don't give to people with severe pen allergy)
    • Bleeding
    • Thrombophlebitis - inflammation of vein often with blood clots
  32. Cephalosporins: generations
    • 1st-4th generations
    • Increasing generations leads to:
    • increasing activity against gram neg bacteria & anerobes
    • increasing resistance to destruction by beta-lactamase (2nd)
    • increasing ability to reach CSF (3rd and 4th): able to get by blood/brain barrier
  33. Cephalexin
    • 1st generation cephalosporin
    • Keflex
  34. Cefoxitin
    • 2nd generation Cephalosporin
    • Mefoxin
  35. Cefotaxime
    • 3rd generation Cephalosporin
    • Claforan
  36. Cefapime
    • 4th generation Cephalosporin
    • Maxipime
  37. Cephalosporins: precautions and ADRs
    • Pseudomembranous colitis
    • Increased risk of bleeding with higher does and longer durations (may give Vit K prophalatic)
  38. Carbapenems
    • Beta lactam abx: broad spectrum
    • Cross sensitivity: penicillins and Cephalosporins
    • Caution: renal failure
    • Use sparingly! Only with folks for whom other abx do not work
    • Imipenem or impenem/cilastatin (Primaxin): broadest coverage of all abx
  39. Carbapenem (e.g.)
    Imipenem or impenem/cilastatin (Primaxin): broadest coverage of all abx
  40. Vancomycin
    • Action: cell wall synthesis (bacteriostatic)
    • Uses: SEVERE infections (c.diff, MRSA)
    • Lyphocin
  41. Vancomycin: ADR
    • Ototoxicity (long duration or high doses)
    • Thrombophlebitis
    • Allergy
    • Nephrotoxicity
  42. Tetracyclines
    • Broad spectrum-inhibit protein synthesis (bacteriostatic)
    • No trade name
    • doxycycline (Vibramycin)
    • minocycline (Minocin)
  43. Tetracyclines: ADR
    • Gastrointestinal
    • Effect on bone and teeth
    • Superinfection
    • Hepatotoxicity
    • Renal toxicity
    • Photosensitivity
  44. Tetracyclines: Precautions
    Do not administer to children < 8 or pregnant women: binds to Ca causes brown discolored teeth
  45. Macroslides
    • Broad spectrum
    • Use if allergic to penicillin
    • Inhibit protein synthesis
    • azithromycin (Zithromax, Zmax)
  46. Clindamycin
    • Cleocin
    • Inhibits protein synthesis (bacteriostatic)
    • Can induce abx-associated pseudomembranous colitis
    • Only for certain anaerobic infections located outside of CNS (e.g., gangrene and resistant strep infections)
  47. Aminoglycosides (e.g.)
    • Most resistant to bacterial enzymes
    • tobramycin (Nebcin)
  48. Aminoglycosides
    • Disrupt protein synthesis and cause rapid bact death
    • Narrow spectrum
    • Aerobic gram neg bacilli
    • Anaerobic bacteria are resistant
    • used with abdominal surgeries and abd infections (good dist in peritoneal fluid)
  49. Aminoglycosides: ADRs
    • Ototoxicity
    • Nephrotoxicity
    • Drink lots of fluids
    • Watch creatine and BUN levels
    • Not used in pregnancy
  50. Sulfonamides
    • 1935: First antibiotic discovered
    • Action: inhibits bacterial synthesis of folic acid
    • Resistance developed quickly
    • Used in combo: trimethoprim/sulfamethoxazole (TMP/SMZ, bactrim)
    • Used in UTIs and AIDs-related pneumonia
    • Not for use in pregnancy
  51. Sulfonamides: ADRs
    • hypersensitivity
    • crystalluria
    • Stevens-Johnson syndrome (serious, severe rxn)
  52. Fluoroquinolones
    • ciprofloxin (Cipro)
    • Broad spectrum
    • interactions with antacids, iron or zinc
  53. Fluoroquinolones: ADRs
    • pseudomembranous colitis
    • tendon rupture
    • rash
    • avoid if pregnant or <18 yrs
  54. Metronidazole
    • Flagyl
    • Bactericidal
    • Uses: protozoal infections, H. pylori
    • Interacts with alcohol
    • ADR: neurotoxicity, allergy, superinfections
  55. Drug regime for TB
    Daily: isoniazid (INH) + rifampin (Rifadin)
  56. isoniazid
    • use: treat TB
    • ADR: hepatotoxicity
    • Give Vitamin B6 always
  57. Rifampin
    • Uses: TB
    • Distribution: through body fluids and CSF
    • causes orange-red urine, feces, saliva, tears
    • ADR: hepatitis (asymptomatic)
  58. Amphotericin B
    • Amphotericin B (Fungizone)
    • IV only not absored PO
    • ADRs: renal injury, fever, HA, chills
    • Use: systemic fungal infections
  59. Antifungals
    • Superficial infections
    • clotrimazole (Lotrimin, Mycelex)
    • nystatin (Mycostatin) for oral candidiasis
  60. Antivirals: non HIV tx
    acyclovir (Zovirax)
  61. Meds for hepatitis
    • Serious meds with serious ADRs.
    • Use caution with people who want to get pregnant
    • interferon alfa (interferon A)
    • Use: Hep B
  62. HIV: Necleoside Reverse Transcriptase Inhibitors
    • Stops DNA building process and virus replication
    • Zidovudine (Retrovir)
    • ADRs: anemia, neutropenia, lactic acidosis, GI effects, CNS (peripheral neuropathy)
  63. HIV: Non-nucleoside reverse transcriptase inhibitors
    • prevents conversion of RNA to DNA
    • efavirenz (Sustiva)
    • used in combination therapy
  64. Protease inhibitor
    • Action: prevents HIV from being assembled and released from infected CD4 cell
    • used in combo therapy
    • lopinavir/ritonavir (Kaletra)