Inhibitors of Nucleic Acid Synthesis
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26 terms
Terms | Definitions |
|---|---|
 Rifampin Spectrum | Mycobacteria (tuberculosis) |
| Rifampin Mechanism | Bacteriocidal: binds bacterial DNA-dependent RNA polymerase blocking the elongation of mRNA |
| Rifampin Adverse Affects | Different rates of acetylation in individuals, Hypersensitivity (fever), inhibit RNA synthesis in mammalian mitochondria, hepatotoxic (AVOID IN LIVER PTS), INDUCTION OF P-450 ENZYMES, body fluids can turn orange |
| Rifampin Resistance | Intrinsic: in some strains the drug is unable to bind to the B-subunit of RNA polymerase Acquired: strain acquires mutations in rpoB gene preventing drug binding (polymerase alteration) |
| Fluoroquinolone Spectrum | Broad spectrum (Gram+, Gram-, atypical organisms), Mycoplasma (intracellular) |
| Fluoroquinolone Names | Ciprofloxacin Levofloxacin Gemifloxacin Moxifloxacin Norfloxacin Ofloxacin |
| Fluoroquinolone Mechanism | Bactericidal - binds to topoisomerases (II (Gram -): prevents relaxation of supercoiled DNA by inhibiting the DNA gyrase, IV (Gram +): interferes with separation of replicated chromosomal DNA into respective daughter cells during cell division) -- CONCENTRATES IN THE PHAGOCYTE |
| Fluoroquinolone Adverse Effects | Arthropathy, Superinfection, GI side effects, headaches and photosensitivity, increase tendonitis and tendon rupture, leg cramps and cartilage injuries in children, contraindicated in pregnant women, prolonged QT interval (chelate cations: do not take with calcium or fortified juices, adjust for renal dysfunction) |
| Fluoroquinolone Resistance | Overprescribed, active efflux of the drug, mutations in topoisomerases, production of enzyme that acetylates drug Moxi: liver elimination (avoid in liver pts), cannot be used for UTIs (no active drug in urine) Cipro and Levo: kidney elimination |
| Metronidazole Resistance | decreased activation of metronidazole, decreased amount of enzyme that reduces metronidazole |
| Metronidazole Spectrum | ANAEROBIC bacteria including Clostridium difficle |
| Metronidazole Mechanism | Bacteriocidal: within anaerobes it is reduced (electron sink, steals reducing capacity) and the reduced form interacts with DNA leading to strand breaks and the inhibition of DNA synthesis (free radical damage) |
| Metronidazole adverse effects | nausea, vomiting, diarrhea, headache, dry mouth, metallic taste, disulfiram-like reaction with alcohol (inhibits ALDH in the ethanol metabolism pathway) |
| Nitrofurantoin Spectrum | UTIs (E.coli and Staph) |
| Nitrofurantoin Mechanism | Bactericidal: reduced which then inactivates or alters bacterial ribosomal proteins and other macromolecules, leads to an inhibition of the synthesis of DNA, RNA, cell wall and protein |
| Nitrofurantoin Adverse Effects | vomiting and pulmonary toxicity |
| Nitrofurantoin Resistance | lack of bacterial resistance |
| TMP-SMX Spectrum | Broad treatment of UTIs, shigella, salmonella, pneumocystis, COPD |
| TMP-SMX Mechanism | sequential blockage of the folate synthesis pathway |
| Trimethoprim Mechanism | Bacteriostatic: inhibits bacterial dihydrofolate reductase (bacterial DHFR is more sensitive to trimethoprim than mammalian) |
| Trimethoprim Adverse Effects | hyperkalemia |
| Trimethoprim Resistance | altered dihydrofolate reductase, increased amounts of dihydrofolate reductase |
| Sulfonamides Names | Sulfamethoxazole Sulfisoxazole Silver sulfadiazine |
| Sulfonamides Mechanism | Bacteriostatic: PABA analog and acts as a competitive inhibitor of Dihydropteroate synthetase (humans don't make this enzyme) |
| Sulfonamides Adverse Effects | hypersensitivity (rash, photosensitivity, drug fever, urticaria), Stevens-Johnson syndrome, cross reaction to other drugs containing sulfonamide moieties, crystalluria leading to acute renal failure, hemolysis if Glucose-6-phosphate dehydrogenase deficient (HEMOLYTIC ANEMIA) |
| Sulfonamides Resistance | change in dehydropteroate synthetase, increased efflux, increased production of PABA acetylation in liver (still active) --> eliminated in active form by urine |
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