Pharm 2 Flashcards
Antimicrobial agent. Subclass?
Substance produced by 1 microbe to inhibit growth of other microbe(s). Antibacterial/fungal/viral agents
3 characteristics of antibacterial activity
Bacteriocidal/static, spectrum, dose or time-dependent effects
Bacteriocidal vs bacteriostatic
Kills sensitive orgs at therapeutic doses; closer MIC & MBC —> more Bacteriocidal, MBC:MIC = 2-4:1 vs stop org growth by inhibiting protein synthesis or w/o killing at therapeutic doses; MBC:MIC = 16x greater —>MBC can’t be achieved by therapeutic doses
Broad vs narrow spectrum activity. Caveats?
Against gram pos & neg —> preferred empiric therapy in serious infxn vs limited types of pathogens —> preferred definitive therapy where pathogen is known. Variability in resistance
What factors play in dose or time dep effects?
Min inhibitory conc (MIC), min Bacteriocidal conc (MBC), dose-dependent killing rate, postabx effect (PAE)
MBC vs MIC
Lowest antimicrobial conc to kill pathogen; always higher than MIC; closer MBC & MIC values —> more cidal —> more kill vs lowest antimicrobial conc to prevent visible pathogen growth; doesn’t kill pathogen; breakpoint sets by CLSI that stay same across hospitals
Lab tests for sensitivity: broth dilution vs Etest vs disk diffusion/Kirby Bauer
Put equal # of bacteria in serial diluted test tubes and find the first test tube that doesn’t have any growth —> MIC vs place Etest strip in agar cx of bacteria and find lowest MIC on zone of inhibition vs streak bacteria cx onto agar plate w/ abx disks —> find which abx disks have zone of inhibition
What is PAE?
Persistent effect on bacterial growth after antibacterial drug = removed
How is there abx resistance?
Suboptimal conc of abx, prolonged exposure of abx; impaired influx of ab —> inc efflux protein expression, mutation/mods/overprod in ab binding proteins, factor-associated protection, drug mods/degradation
Steps to find the right abx for pts
Get hx, PE, s/s, predisposing factors to confirm presence of infxn —> do gram stain, cx, sensitivity, collect a sample to ID pathogen —> consider infected site, host factors, drug factors to find empiric/presumptive therapy
Prophylactic vs empirical vs definitive therapy + examples
Used to prevent dz for invasive procedures, dz transmission, immunocompromised; ex: amoxicillin before dental procedure for pt w/ prosthetic heart valve, giving antiviral to ppl exposed to flu vs tx pt to cover pathogens most likely present —> broad spectrum; ex: nitrofurantoin for UTI vs tx pt based on specific pathogen —> narrow spectrum, dec risk of abx resistance; ex: give amoxicillin for S. Pneumonia
Host vs drug factors
Age, preg, metab, organ dysfxn, concomitant drugs/drug interaction, concomitant dz states, allergy vs pharmacokinetics/dynamics, tissue penetration (CNS, bone, prostate, ocular = hard to penetrate), admin route, spectrum of activity, adverse effect profile (toxicities, sz, hematologic), cost
Combination abx therapy. Disadvantages?
Broaden spectrum coverage of empiric therapy, achieve synergistic activity, prevent resistance. Cost, adverse effects, superinfxn
Antagonistic vs additive vs synergistic vs indifferent combination abx therapy
Combined effect < single effect of drug (2+2<2) vs combined effect = sum of single effects (2+2=4) vs combined effect > sum of single effects (2+2>4) vs combined effect = greatest effect by either drug
Failures of abx therapy
Dz might not be bacterial, undetected pathogen, inappropriate drug selection/dose/admin route, immunosuppressive, surgical intervention, bacterial resistance
How are new drugs discovered?
Chem mods, random screening, drug design/biotech, random chance, toxicity/AE/safety assessment, animal studies
Safety testing: acute tox vs subacute/chronic tox vs chronic tox vs reproductive performance vs carcinogenic potential vs mutagenic potential
2 species, 2 routes; determines no effect dose and max tolerated dose vs 2 species, 3 doses; longer duration of expected clinical use —> longer subacute test vs 1 rodent + 1 nonrodent for >/= 6mo; run concurrently w/ clinical trials vs 2 species; on mating behavior, reproduction, birth defects vs 2 species, 2 yrs; determine pathology vs determine genetic stability and mutation in bacteria (Ames test)
Limitations of animal models
Expensive, large # of animals needed, diff species —> diff ADME than humans, not good at detecting AE
What makes a good clinical trial?
Using scientific method: good testable hypothesis; picking pts (in/exclusion criteria), ctrl, sample size; pt compliance; finding meaningful indices of drug, choose effects for observation; observations must be converted to valid data
bactericidal fluoroquinolones: cipro vs levo vs moxi vs delafloxacin
gram neg w/ Pseudo, atypical, poor gram pos vs gram pos/neg w/ Pseudo, resp Q vs gram pos/neg W/O Pseudo, resp Q, not for UTI b/c no renal elim vs gram pos w/ MRSA, gram neg w/ Pseudo, some anaerobes
bactericidal nitroimidazoles: metronidazole MOA vs preg cat vs indications vs contraindications vs AE vs drug interaction
prodrug reduced in ANAEROBES to reactive reduction products –> lose DNA helix structure –> disrupt DNA/nucleic acid synthesis vs preg cat B –> don’t use vs intraabd anaerobic infxn, STI, aspiration PNA, SSTI, prophylaxis vs don’t use w/in 3d of alc or propylene glycol –> disulfiram rxn vs N/V/D, HA, metallic taste vs warfarin, alc, propylene glycol
bactericidal rifampin MOA vs preg cat vs spectrum of activity vs indication vs AE vs drug interaction
antitubercular agent; inhibits DNA-dep RNA polymerase –> no chain formation for RNA synthesis vs preg cat C vs staph, mycobacteria vs TB, meningococcal prophylaxis, prosthetic valve endocarditis vs orange urine, tears, sweat; blood dyscrasias; hep/jaundice, GI, flu like sxs vs induces CYP enzymes, 3A4
bactericidal nitrofurantoin MOA vs preg cat vs spectrum of activity vs indication vs contraindication vs AE
reduced by bacterial flavoproteins to reactive intermediates that inactivate/alter bacterial ribosomal proteins –> inhibit DNA/RNA/cell wall/protein synthesis, aerobic metab vs preg cat B –> hemolytic anemia in newborn vs E coli, E faecalis, K pneu, staph saprophyticus vs uncomplicated cystitis vs renal impairment –> avoid use w/ CrCl <30-60mL/min d/t urine and neurotox vs hemolytic anemia –> avoid in G6PD defic, pulm tox, GI upset, yellow/brown urine
1 vs 2 vs 3 vs 4 vs 5 gen cephalosporins fight against?
gram pos cocci, some gram neg vs gram pos, more gram neg; IV = the only cephalosporins against gram neg anaerobes vs gram pos, even more gram neg w/ Neisseria; ceftazidime only does Pseudo (no gram pos or other gram neg) vs gram pos, resistant gram neg w/ Pseudo vs gram pos, lose some gram neg than gen4, MRSA