Antibacterial Drugs Flashcards
Pharmacotherapy with penicillins
- Prototype drug: penicillin G (Pentids)
- Mechanism of action: to kill bacteria by disrupting their cell walls
- Primary use: as drug of choice against streptococci, pneumococci, and staphylococci organisms that do not produce penicillinase
- Adverse effects: diarrhea, nausea, vomiting, superinfections, anaphylaxis
Penicillins
- Most effective against gram-positive bacteria
- Kill bacteria by disrupting cell wall with beta-lactam ring
- Beta-lactamase or penicillinase is enzyme allowing bacteria to be resistant
- New penicillins are penicillinase-resistant and are useds as combination drugs
◦In other words, they are less likely to become resistant to certain bacteria
Penicillin adverse effects
•One of safest classes of antibiotic
•Allergy most common adverse effect
•If client allergic to penicillin, avoid cephalosporins
◦Possibility of cross-hypersensitivity
•Other adverse effects
◦Skin rash; decreased RBC, WBC, or platelet counts
Penicillin drug therapy••Assess for presence or history of bleeding disorders
◦Cephalosporins may reduce prothrombin levels
•Assess renal and hepatic function
•Avoid alcohol
◦Some cephalosporins cause disulfiram (Antabuse)–like reaction with alcohol for presence or history of bleeding disorders
◦Cephalosporins may reduce prothrombin levels
•Assess renal and hepatic function
•Avoid alcohol
◦Some cephalosporins cause disulfiram (Antabuse)–like reaction with alcohol
- Assess previous drug reactions to penicillin
- Avoid cephalosporins if client has history of significant penicillin allergy
- Monitor for hyperkalemia and hypernatremia
- Monitor cardiac status, including ECG changes
Cephalosporin
•Similar in structure and function to penicillins
•Widely prescribed anti-infective class
•More than 20 cephalosporins available
◦With 4 generations
- Cross-sensitivity with penicillins (5–10% of population)
- Classified by generations
•Generations of cephalosporins
◦First through fourth, they become increasingly more effective and broader in spectrum.
◦Third and fourth can enter the cerebral spinal fluid
Pharmacotherapy with cephalosporin
- Prototype drug: cefotaxime (Claforan)
- Mechanism of action: to act with broad-spectrum activity against gram-negative organisms
- Primary use: for serious infections of lower respiratory tract, central nervous system, genitourinary system, bones, blood, and joints
- Adverse effects: hypersensitivity, anaphylaxis, diarrhea, vomiting, nausea, pain at injection site
Cephalosporin therapy
•Assess for presence or history of bleeding disorders
◦Cephalosporins may reduce prothrombin levels
•Assess renal and hepatic function
•Avoid alcohol
◦Some cephalosporins cause disulfiram (Antabuse)–like reaction with alcohol
Tetracyclines
•Some of broadest spectrums of any antibiotic class
•Drugs of choice for only a few diseases because of large number of resistant bacterial strains
◦Rocky Mountain spotted fever
◦Typhus, cholera, Lyme disease
◦Peptic ulcers caused by H. pylori
◦Chlamydial infections
•Inhibit bacterial protein synthesis with bacteriostatic effect•Tetracyclines decrease effectiveness of oral contraceptives
◦Alternate birth-control method should be used while taking medication
•Use with caution in clients with impaired kidney or liver function
- Photosensitivity may result
- Do not take with milk products, iron supplements, magnesium-containing laxatives, or antacids DO NOT TAKE WITH OTHER MINERALS
Pharmacotherapy of tetracycline
- Prototype drug: tetracycline HCL (Achromycin, others)
- Mechanism of action: effective against broad range of gram-positive and -negative organisms
- Primary use: chlamydiae, rickettsiae, and mycoplasma
- Adverse effects: superinfections, nausea, vomiting, epigastric burning, diarrhea, discoloration of teeth, photosensitivity
Tetracycline adverse effects
•Bind with calcium and iron to decrease absorption by up to 50%
◦Do not take with milk.
•Photosensitivity
•Permanent yellow-brown tooth discoloration in children
•Risk for superinfection is high
•Pregnancy Category D
Tetracycline therapy
•Contraindicated for clients who are pregnant or lactating
◦Effect on linear skeletal growth of fetus and child
•Contraindicated in children less than 8 years of age
◦Permanent mottling and discoloration of teeth
Amoglycosides
•Narrow-spectrum drugs, bacteriocidal
•Reserved for serious systemic infections caused by aerobic gram-negative bacteria
◦E. coli, serratia, proteus, klebsiella, and pseudomonas
•Inhibit bacterial protein synthesis
•More toxic than most antibiotics
•Have potential to cause serious adverse effects
◦Ototoxicity, nephrotoxicity, neuromuscular blockade
•Note difference in spelling “mycin” and “micin”—reflects origins of drug
Pharmacotherapy with aminoglycosides
•Prototype drug: gentamicin (Garamycin)
•Mechanism of action: to act as broad-spectrum, bacteriocidal antibiotic
•Primary use: for serious urinary, respiratory, nervous, or GI infections
◦Often used in combination with other antibiotics
◦Used parenterally or as drops (Genoptic) for eye infections
•Adverse effects: ototoxicity and nephrotoxicity
Aminoglycosides therapy
- Monitor for ototoxicity and nephrotoxicity
- Hearing loss may occur after therapy has been completed
- Neuromuscular function may also be impaired
- Increase fluid intake, unless otherwise contraindicated, to promote excretion
Fluoroquinolones
•Are bacteriocidal and affect DNA synthesis by inhibiting two bacterial enzymes
•All have activity against gram-negative pathogens
•Newer drugs in class have activity against gram-positive microbes.
•Now four generations
◦Used for infections of respiratory system, GI and GU tracts, skin and soft tissue infections
