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28 Cards in this Set
- Front
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Penicillin G |
First line (except potentiated, then second line) Narrow spectrum : Gram +aerobes and Anaerobes Inhibit cell wall synthesis by binding to and inactivating material transpeptidase causing cell lysis Short half life Not acid stable Distributes to most tisses except CNS and uninflamed prostateExcreted unchanged in urine.10% filtration, 90% active tubular section. 1/2 life can increase 20 fold in renal failure Resistance fairly common due to poor penetration of complex gram - wall and aquaired bacterial penicillinase which can be transferred to other bacteria. Time dependant AMD |
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Dicloxavillin |
First line (except potentiated, then second line) Penicillinase resistant Inhibit cell wall synthesis by binding to and inactivating material transpeptidase causing cell lysis Anti staphylococcal: used against gram + aerobe Staph Acid Stable Distributes to most tisses except CNS and uninflamed prostateExcreted unchanged in urine. 10% filtration, 90% active tubular section. 1/2 life can increase 20 fold in renal failure Resistance fairly common due to poor penetration of complex gram - wall and aquaired bacterial penicillinase which can be transferred to other bacteria. Time dependant AMD |
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Ampicillin |
First line (except potentiated, then second line) Extended spectrum: Gram + aerobes Anaerobes Some Gram - Aerobes (enterobacteriacease like E. Coli) Inhibit cell wall synthesis by binding to and inactivating material transpeptidase causing cell lysis Used in combination with penicillinase inhibitors such as clavulanic acid Oral bioavailibilty 90%+ Distributes to most tisses except CNS and uninflamed prostate Excreted unchanged in urine. 10% filtration, 90% active tubular section. 1/2 life can increase 20 fold in renal failure Resistance fairly common due to poor penetration of complex gram - wall and aquaired bacterial penicillinase which can be transferred to other bacteria. Time dependant AMD |
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1st gen cephalosporin |
Eg cephalexin (one of few acid stable) First line Gram+ aerobes Some Gram - aerobes (E.coli) Anaerobes 5-10% of people with penicillin allergy are also allergic to cephalosporins Inhibit cell wall synthesis by binding to and inactivating material transpeptidase causing cell lysis not destroyed by penicillinases, but may be inactivated by beta-lactamases Time dependant AMD |
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2nd gen cephalosporins |
Some Gram + and - often used for anaerobes 5-10% of people with penicillin allergy are also allergic to cephalosporins Inhibit cell wall synthesis by binding to and inactivating material transpeptidase causing cell lysis Time dependant AMD |
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3rd gen cephalosporins |
eg cefotaxime First line Used for gram - aerobes such as enterobacteriacease and some gram _ and anaerobes Cross BBB so good for bacterial meningitis Inhibit cell wall synthesis by binding to and inactivating material transpeptidase causing cell lysis not destroyed by penicillinases, but may be inactivated by beta-lactamases Time dependant AMD |
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Gentamicin |
Aminoglycoside topical - first line systemic - second line Broad spectrum Systemic for severe gram negative aerobic infections (septicaemia) Topical (staph, E. Coli) Highly ionized, limits ability to cross membranes. Only 3% absorbance orally so must be given parenterally for systemic treatment. Inhibit bacterial protein synthesis by binding to bacterial ribosomes and causing wrong AAs to be incorporate which can cause lethal porins to kill - bacterial cell = bactericidal Effective against Gram - aerobes, staph (gram +) and mycoplasma (atypical) Resistance: Constitutive: entry of drug into cell is O2 dependent so no good for anaerobes and plasma required: amynoglycosidases Concentration dependant, so best to give 1 dose day and allow washout period. |
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Tobramycin |
Clinically interchangeable with gentamicin and reserved for bacteria resistant to gentamicin More expensive Bactericidal |
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Amikacin |
Resistant to many aminoglycosidases Resistance rises with use Used systemically for infections resistant to gentamicin Bactericidal |
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Tetracyclines |
First line Bind to bacterial ribosomes 30S subunit inhibiting protein synthesis Binding is reversible - bacteriostatic Potential to be broad spectrum but resistance became common. Main drug used for atypical bacteria Can be oral, injectable, or topical Divalent cations in food inhibit oral absorption of tetracyclines Some are water soluble and distribute to extraceullar fluid half the drug is excreted unchanged while half metabolized in liver and active transport into bile Some are lipid soluble and can enter cell entirely metabolized in liver and secreted in bile Most enter every tissue but CNS Resistance is aquried: efflux pump removes drug from bacterial cell Efflux pump may be overwhelmed by high drug concentration so topical application can improve efficacy time dependant TMD |
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Chlortetracycline |
water soluble tetracycline |
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Tetracycline |
water soluble tetracycline |
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oxytetracycline |
water soluble tetracycline |
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Doxycycline |
Lipid soluble tetracycline |
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Minocycline |
lipid soluble tetracycline distributes to CNS |
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Sulfamindes |
First line Infective used alone. Effectiveness restored when combines with diaminopyrimides such as trimethoprim (TM) to make Referred to as TMS or co trimoxazole Bactericidal Stops synthesis of Folic acid from PABA. Sulfanimdes resemble PABA and act as competitive inhibitor for dihydropteroate synthetase which catalyzes condensation of PABA to pteridine Trimethoprim resembles pteridine portion of dihydrofolic acid which inhibits dihydrofolate r.eductase which catalyzes the reduction of dihydrofolic acid to tetrahydrofolic acid. Work against atypical bacteria and lower UTI infections from gram + and - aerobes where concentration of drug in urine overwhelms resistance mechanisms. Extremely broad spectrum when first marketed but rapid selection resistance occurred within first decade of use. Distributes to all tissues Some excreted unchanged in urine, some hepatic metabolism. Metabolite accusation in renal tubes can cause severe damage in dehydrated patients. Rapid development of resistance via acquisition of altered dihydropteroate synthetase enzyme encoded by plasmid and new enzyme binds PABA but not sulphonamide. Can occur during treatment Increased PABA uptake in presence of pus (drug ineffective) reduced uptake of drug Resistance to TM usually due to acquisition of altered form of dyhydrofolate reductase with low affinity for TM |
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Ciprofloxacin |
Second line Fluoroquinolone Long half live and excellent bioavailibity (oral ~100%) Long half life (4 hours) Damage DNA by inhibiting DNA gyrates and topoisomerase Effective against Staph (gram + aerobe) Gram -Aerobes, and atypical bacteria Ineffective against all anaerobes renal excretion Resistance is sudden and stable due to mutation of bacterial genres, DNA gyrate or Topoisomerase genes which inhibit FQ binding. Could also be efflux pump. Mutation could cause increased expression of a pump that is normally present in low numbers -> efficient in removal of drug from bacterial cell Some mutations confer resistance to one drug, some resistance to all FQs Can concentrate in lung |
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Amphotericin B |
Polyene Broad spectrum, fungicidal, high systemic toxicity Target ergosterol in plasma membrane. Enters membrane and causes lysis. Can also bind to cholesterol somewhat making it toxic to host cells. Broad spectrum (compared to azoles) Used for patients with life threatening systemic mycoses (or immunocompromised patients) Ineffective against dermatophytes) Most toxic antimicrobial drug in clinical use. can be prepared with bile salts for water suspension which adds toxicity, lipid complex formulations are far safer. Distributes everywhere but CNS. Lipid complexes can concentrate in lungs and reticuloendothelial system. Expensive Lipid containing formations more toxic than echinocandins and no more effective. Long half lives Eliminated in liver through bile and metabolite and active drug excreted in urine. |
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Ketozonacole |
Azole - imidazole Broad spectrum, fungistatic, very low toxicity Used systemically, less effective and more toxic than newer triazoles Inhibit fungal P450 enzymes involved in ergosterol formation inhibit fungal membrane synthesis (fungistatic effect( Inhibit fungal and mammalian sterol synthesis (esp. cortisol and testosterone) _> endocrine effects are common with systemic therapy |
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Itraconazole |
Azole Broad spectrum, fungistatic, very low toxicity good oral bioavailability safe but teratogenic Most commonly used for systemic anti fungal therapy Used interchangeable with imidazole for topical use Inhibit fungal P450 enzymes involved in ergosterol formationinhibit fungal membrane synthesis (fungistatic effect) less effect on mammalian sterol synthesis and vernally very safe and longer half lives compared to imidazoles Usually fungistatic but high doses can be fungicidal Distributes excellent except to CNS and concentrates in skin half life is 3 days and mainly hepatic metabolic administered orally Many non threatening systemic fungal infections -> fairly broad spectrum of activity, but not as broad as newer triazole or polyenes sometimes used in place of or following amphotericin B for life threatening infections |
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Clotrimazole |
Azole - imidazole teratogenic good oral bioavailability Broad spectrum, fungistatic, very low toxicity Used interchangeable with triazoles for topical use Inhibit fungal P450 enzymes involved in ergosterol formationinhibit fungal membrane synthesis (fungistatic effect( Inhibit fungal and mammalian sterol synthesis (esp. cortisol and testosterone) |
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Miconazole |
Azole - imidazole good oral bioavailability Broad spectrum, fungistatic, very low toxicity Used interchangeable with triazoles for topical use Inhibit fungal P450 enzymes involved in ergosterol formationinhibit fungal membrane synthesis (fungistatic effect( Inhibit fungal and mammalian sterol synthesis (esp. cortisol and testosterone) |
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Caspofungi |
Pneumocandins an dachinocandins Newest AF drugs, low toxicity and replacing polyenes for systemic therapy Inhibits beta-(1,3)-D-glucan synthase, an enzyme necessary for the synthesis of an essential component of the cell wall of severel fungi. Generally fungicidal Resistance to echinocandins is still uncommon and in humans all agents are well tolerated. Drugs are expensive |
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Terbinafine |
Treat dermatophytosis (ringworm) Inhibits ergosterol synthesis in virtually all dermatophytes Toxic metabolites accumulates - fungicidal More effective than intraconazole Given orally for serious infections Enters nearly formed keratin -> therapy continues for ~3 months (much longer for nails |
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Fluxonazole |
Triazole same as itraconazole except not oral, eliminated in urine and distributes well to CNS 100% oral bioavailability and can be given with IV. nay be as effective as amphi B for cryptical meningitis effective against dermatophytes |
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Erythromycin |
First line One of first macrolides Short half life weak bases Gram +, Anaerobes, Gram - (but not enterobacteriacease) and some atypical Used for intracellular pathogens, respiratory infections, in place of penicillin in patient with allergy. Erythromycin inhibits P450 enzymes Stimate moltilin receptors |
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Newer Macrolides |
Second line One of safest classes of antibacterial drugs Penetrate cells better than most drug classes eg azithromycin Concentrate in lung and lung macrophages Very long half lives weak bases inhibit protein synthesis by reversibly binding 50S ribosome subunit mainly effective agains gram - aerobes (slightly effective against everything else) Commonly used for community acquired bacterial pneumonia resistance during therapy may be due to plasmid encoded macrolide efflux pump gene mutation of ribosomal methylate gene, such that methylate no longer binds macrolides |
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Chloramphenicol |
Almost ideal antimicrobial Broad spectrum Generally very safe distributes well to all tissues except prostate, penetrates cornea extremely well oral, topical, and injectable forms Inhibits ptoein (biosteric) by inhibiting peptidyltransferase Probleem is rare but fatal aplastic anemia in humans |
