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113 Cards in this Set

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MOA of penicillins
Bind PBPs to inhibit transpeptidation reactions in peptidoglycan cross-linking --> inhibit cell wall synthesis
Mechanism of resistance to penicillin
Beta-lactamases (staphylococci); structural change in PBPs (MRSA); change in porin structure (pseudomonas)
Narrow spectrum penicillins
Penicillin G and V. Strep, pneumococci, meningococci, treponema
Very narrow spectrum penicillins
Nafcillin, methcillin, oxacillin. Staph. If MRSA use vancomycin.
Broad spectrum penicillins
Ampicillin, amoxicillin. Gram+ cocci (except staph), Listeria, H. influenzae, E. coli. Borrelia and H. pylory: amoxi
Extended spectrum penicillins
Ticarcillin, piperacillin, azlocillin. Increased activity against gram- plus anti-pseudomonal
Beta-lactamase inhibitors
Clavulanic acid, sulbactam. Use in combination with broad and extended spectrum penicillins
Pharmacokinetics of penicillins
Most are eliminated via active tubular secretion. Nafcillin and oxacillin are eliminated in bile. Ampicillin undergoes enterohepatic circulation but is excreted by the kidney. Benzathine penicillin G repository form (t1/2: 2 weeks)
Side effects of penicillins
Hypersensitivity (5-7%). Urticarial skin rash to anaphylaxis. Interstitial nephritis (methicillin).
First generation cephalosporins
Cefazolin, cephalexin. Gram+ cocci (not MRSA), E. coli, Klebsiella pneumoniae, some proteus. Surgical prophylaxis
Second generation cephalosporins
Cefotetan, cefaclor, cefuroxime. Increased gram- coverage, including some anaerobes
Third generation cephalosporins
Ceftriaxone (IM), cefotaxime (IV), cefdinir, cefixime (oral). Gram+ and gram- cocci plus gram- rods. Enter CNS. Use in meningitis, sepsis
Fourth generation cephalosporins
Cefepime (IV). Enter CNS, resistant to betalactamases
Pharmacokinetics of cephalosporins
Active tubular secretion blocked by probenecid. Cefoperazone and ceftriaxone largely eliminated in bile.
Side effects of cephalosporins
Hypersensitivity (2%), rashes, fever, postive Coombs test, disulfram-like effect
Drugs to use in case of penicillin/cephalosporin allergy
Macrolides for gram+, aztreonam for gram- rods
Imipenem and meropenem
Resistant to betalactamases. Active against gram+ cocci, gram- rods and anaerobes. Use in life-threatening infections. Used IV. Imipenem is given with cilastatin to inhibit rapid renal metabolism by dehydropeptidase. Side effect: seizures
Aztreonam
Resistant to betalactamases. Used IV against gram- rods. No cross-allergenicity with penicillins or cephalosporins
Vancomycin MOA
Binds D-Ala-D-Ala pentapeptide to inhibit elongation of peptidoglycan chains. Does not bind PBPs.
Uses of vancomycin
MRSA, enterococci, C. difficile (backup drug)
Resistance to vancomycin
Terminal D-ala is replaced with D-lactate in muramyl pentapeptide
Pharmacokinetics of vancomycin
Used IV and orally (not absorbed) in colitis. Enters most tissues but not CNS. Eliminated by renal filtration. Long t1/2
Side effects of vancomycin
"Red man syndrome" (histamine release); permanent ototoxicity; nephrotoxicity
Antibiotics that act on 30S ribosomal subunit
Aminoglycosides, tetracyclines. "buy AT 30, CCEL at 50".
Antibiotics that act on 50S ribosomal subunit
Chloranphenicol, clindamycin, erythromycin (macrolides), linezolid. "buy AT 30, CCEL at 50"
Antibiotics that inhibit formation of initiation complex
Aminoglycosides (30S), linezolid (50S)
Antibiotics that block attachment of aminoacyl-tRNA to A site
Tetracyclines (30S), dalfopristin (50S)
Antibiotics that inhibit peptidyltransferase (peptide bond formation)
Chloranphenicol (50S)
Antibiotics that inhibit translocation
Macrolides (50S), clindamycin (50S)
Mecanisms of resistance to macrolides and clindamycin
Methyltransferases alter drug binding site on the 50S ribosome; active transport out of cell
Mechanism of resistance to tetracyclines
Tetracycline pumps transport drug out of the cell
Mechanism of resistance to aminoglycosides
Conjugation enzymes
Mechanism of resistance to sulfonamides
Change in target enzyme decreases drug sensitivity; formation of PABA; use of exogenous folic acid
Mechanism of resistance to fluoroquinolones
Change in target enzyme decreases drug sensitivity; pumps transport drugs out of the cell
Mechanism of resistance to chloranphenicol
Formation of inactivating acetyltransferases
Pharmacokinetics of aminoglycosides
Polar compounds not absorbed orally or widely distributed. Renal elimination. Modify in renal dysfunction
Aminoglycoside drugs
Gentamicin, tobramycin, amikacin: gram- aerobic rods (pseudomonas, brucella, legionella); Streptomycin: TB, plague and tularemia; neomycin
Side effects of aminoglycosides
Nephrotoxicity (6-7%), ototoxicity enhanced by loop diuretics.
Tetracycline drugs
Tetracycline, doxycycline, minocycline, demeclocycline
Uses of tetracyclines
Chlamydia, mycoplasma, H. pylory, Rickettsia, Borrelia, Brucella, Vibrio
Phamacokinetics of tetracyclines
Metabolized by kidney (most), and liver (doxycycline). Decrease absorption of divalent cations by chelation.
Side effects of tetracyclines
Tooth enamel dysplasia, decreased bone growth (avoid in children), phototoxicity, contraindicated in pregnancy
Drugs that cause phototoxicity
Tetracyclines, sulfonamides, quinolones
Drugs that are nephrotoxic
Vancomycin, aminoglycosides, amphotericin B, cisplatin, cyclosporine
Drugs that are ototoxic
Aminoglycosides, loop diuretics
Pharmacokinetics of chloranphenicol
Orally effective, enters CNS, metabolized by hepatic glucoronidation, inhibits P450
Side effects of chloranphenicol
Dose-dependant bone-marrow suppression, "gray baby" in neonates (decreased glucoronosyl transferase)
Macrolide drugs
Erythromycin, azithromycin, clarithromycin
Uses of Erythromycin
Gram+ cocci, atypicals (chlamydia, mycoplasma, ureaplasma), legionella, campylobacter
Uses of azithromycin
Gram+ cocci, atypicals (chlamydia, mycoplasma, ureaplasma), legionella, campylobacter, more activity in respiratory infections
Pharmacokinetics of macrolides
Erythromycin and clarithromycin: metabolized by liver, excreted in bile, inhibit P450, not safe in pregnancy. Azithromycin: excreted by kidney, doesn't inhibit P450, safer in pregnancy
Side effects of macrolides
Stimulate motilin receptors and cause GI distress, reversible deafness, cholestasis, jaundice
Drugs to avoid in pregnancy
Aminoglycosides, erythromycin, clarithromycin, fluoroquinolones, sulfonamides, tetracyclines
Uses of clindamycin
Gram+ cocci, anaerobes, toxoplasmosis. Use in gram+ osteomyelitis. Can cause pseudomembranous colitis
Linezolid
VRSA, VRE, drug-resistant pneumococci. Side effect: bone marrow suppression (platelets)
Streptogramin drugs
Quinupristin-dalfopristin
MOA of streptogramins
Bind 50S ribosomal subunit
Uses of streptogramins
Vancomycin resistant staph (VRSA), vancomycin resistant enterococci (VRE), drug-resistant gram+ cocci
Inhibitors of nucleic acid synthesis drugs
Sulfonamides, trimethoprim, pyrimethamine
MOA of sulfonamides
Inhibits dihydropteroate synthetase which inhibits folic acid synthesis
MOA of trimethoprim
Inhibits dihydrofolate reductase which inhibits folic acid synthesis
Uses of trimethoprim-sulfamethoxazole
DOC in Nocardiosis; mycobacteria; gram+ cocci, E. coli, Salmonella, Shigella, H. influenzae, P. carinii, toxoplasma
Pharmacokinetics of sulfonamides
Hepatically acetylated; renally excreted metabolites cause crystalluria; high protein binding
Side effects of sulfonamides
Hypersensitivity, Steven Johnson, phototoxicity, GI distress, hemolysis in G6PDH deficiency
Side effects of trimethoprim
Bone marrow suppression, enterocolitis
Quinolone drugs
Norfloxacin, ciprofloxacin, ofloxacin, levofloxacin
MOA of quinolones
Bactericidal. Inhibit topoisomerase II (DNA gyrase).
Uses of quinolones
UTIs resistant to cotrimoxazole, PID (chlamydia, gonococcus), skin and bone infections by gram-, diarrhea to shigella, salmonella, E. coli, campylobacter
Pharmacokinetics of quinolones
Iron and Ca+ limit their absorption, eliminated by kidney active secretion (inhibited by probenecid)
Side effects of quinolones
GI distress, phototoxicity, rashes, tendonitis, increases QT interval, contraindicated in pregnancy and children
Regimens used in H. pylori infections and ulcers
BMT: bismuth, metronidazole, tetracyclines or clarithromycin, amoxicillin, omeprazole
Uses of metronidazole
Giardia, trichomonas, entamoeba, gram- anaerobics, clostridium (DOC pseudomembranous colitis)
MOA and resistance to isoniazid
Inhibits mycolic acid synthesis; prodrug requires conversion by catalase; resistance: deletions in katG gene encodes catalase needed for activation; deletions in inhA gene encodes acyl carrier protein, the target
Side effects of isoniazid
Age-dependant hepatitis, peripheral neuritis (use B6), sideroblastic anemia (use B6), hemolysis in G6PDH deficiency, drug-induced lupus in slow acetylators
MOA and resistance to rifampin
Inhibits DNA-dependant RNA polymerase; resistance via change in enzyme
Side effects of rifampin
Hepatitis, induction of P450, red-orange metabolites
MOA of ethambutol
Inhibits synthesis of cell wall component arabingalactan
Side effects of ethambutol
Dose-dependant retrobulbar neuritis --> decreases visual acuity and red-green discrimination
Side effects of streptomycin
Deafness, vestibular dysfunction, nephrotoxicity
Polyene drugs
Amp B, nystatin
MOA of polyenes
Formation of artificial pores in the ergosterol membranes disrupts membrane permeability
Uses of amphotericin B
Severe infections by Aspergillus, Candida, Cryptococcus, Histoplasma, Mucor, Sporothrix
Uses of nystatin
Topical localized infections; too toxic for systemic use
Pharmacokinetics of amphotericin B
Given by slow IV infusion, does not enter CNS, slow t1/2 > 2 weeks, hepatic metabolism and renal elimination
Side effects of amphotericin B
Infusion-related: fever chills, muscle rigor, hypotension alleviated by NSAIDs, antihistamines, meperidine, steroids. Dose-dependant: nephrotoxicity, decreased GFR, tubular acidosis, anemia
Azole drugs
Ketoconazole, fluconazole, itraconazole, clotrimazole
MOA of azoles
Fungicidal by inhibiting 14-alpha-demethylase which converts lanosterol to ergosterol
Uses of ketoconazole
DOC for Paracoccidioides; backup for Blastomyces, Histoplasma; Oral use in mucocutaneous candidiasis or dermatophytoses
Uses of fluconazole
DOC for esophageal and invasive candidiasis and coccidioidomycoses. Prophylaxis and suppression of cryptococcal meningitis
Uses of itraconazole
DOC in blastomycoses and sporotrichoses
Uses of clotrimazole
Used topically for candidal and dermatophytic infections
Pharmacokinetics of ketoconazole
Orally effective; absorption decreased by antacids; metabolized by liver enzymes; inhibits P450
Pharmacokinetics of itraconazole
Orally effective; absorption increased by food; metabolized by liver enzymes; inhibits P450
Pharmacokinetics of fluconazole
Orally effective; enters CSF; eliminated in the urine in unchanged form
Side effects of azoles
Decreased synthesis of cortisol and testosterone --> decreased libido, gynecomastia, menstrual irregularities; Increased liver function tests and rare hepatotoxicity
Drugs that block viral penetration and uncoating
Amantadine, enfurvitide
Drugs that inhibit viral DNA polymerases
Acyclovir, foscarnet, ganciclovir
Drugs that inhibit viral RNA polymerases
Foscarnet, ribavirin
Drugs that inhibit viral reverse transcriptase
Zidovudine, didanosine, zalcitabine, lamivudine, stavudine, nevirapine, delavirdine, efavirenz
Drugs that inhibt viral aspartate protease
Indinavir, ritonavir, saquinavir, nelfinavir
Drugs that inhibit viral neuraminidase
Zanamivir, oseltamivir
Drugs used to treat herpes
Acyclovir, ganciclovir, foscarnet
Acyclovir
Activated by viral thymidine kinase, inhibitor and chain terminator of DNA polymerase. Use for HSV ans VZV. Side effects: crystalluria, neurotoxicity
Ganciclovir
Activated by viral thymidine kinase, inhibitor and chain terminator of DNA polymerase. Use for HSV, VZV, CMV, AIDS retinitis and transplant patients. Side effects: hematotoxicity, crystalluria, rash
Foscarnet
Inhibits viral DNA and RNA polymerases. Use for HSV, VZV, CMV, AIDS retinitis, transplant patients. Side effects: nephrotoxic acute tubular necrosis, hypocalcemia (tremors, seizures)
Zidovudine (ZDV, AZT)
Converted to triphosphate that inhibits reverse transcriptase and causes chain termination. Resistance by mutations of RT gene.
Drug interaction of zidovudine (ZDV, AZT)
Increase levels of ZDV: azoles, cimetidine, indomethacin, probenecid, TMP-SMX. Decrease levels of ZDV: rifampin
Side effects of ZDV
Neutropenia, anemia, granulocytopenia, headache, myalgias, neuropathy, lactic acidosis
MOA enfuvirtide
Binds gp41 and inhibits fusion of HIV-1 to CD4 cells
Needle stick HIV prophylaxis
ZDV + 3TC + indinavir
Pregnancy HIV prophylaxis
ZDV trimester 2 and 3 plus 6 weeks to neonate reduces vertical transmission by 80%. Or ZDV intrapartum reduces transmission by 50-60%
Amantadine
Blocks attachment, penetrationa and uncoating of Influenza A. May decrease flu symptoms. Side effects: nervousness, insomnia, atropine-like effects
Uses of interferons
Antiviral: HBV, HCV; antiumor: Kaposi, CML, multiple myeloma, renal CA; Immunoregulatory: mutiple sclerosis