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Wednesday, June 6, 2012

Pharmacology: Antibiotics / Antimicrobial Drugs


ANTIBIOTICS / ANTIMICROBIAL DRUGS




A.   AMINOGLYCOSIDES

Prototype: Gentamicin (Garamycin)
Action: Acts by suppressing protein synthesis in bacterial cell; bactericidal.
Use: serious gram-negative bacterial infections, eye infections.
Adverse effect: toxicity, nephrotoxicity, neuromuscular blockade, and hypersensitivity photosensitivity with topical preparations

Related drugs:
  1. Amikacin (Amikin)
  2. kanamycin (Kantrex)     are given orally
  3. Neomycin (Niobiotic)     to prepare the  bowel for surgery
  4. Streptomycin
  5. Tobramycin
  6. Netilmicin
*Neomycin- given to persons in hepatic failure to reduce ammonia levels.




B.  PENICILLINS

Prototype: Penicillin G Potassium
Action: inhibits cells wall synthesis of microorganism; bactericidal
Use: Systemic infections caused by gram (+) cocci; syphilis, prophylaxis for rheumatic fever and bacterial endocarditis
Adverse Effect: Hypersensitivity, G.I upset, potassium poisoning, irritation at injection site.

Nursing Implications: give oral form on an empty stomach with a full glass of water; IV solutions are stable at room temperature for 24 hrs. only
Probenecid: may be given to increase blood levels of penicillin.

Related drugs:
1. Penicillinase –resistant penicillins
  -used to treat infection caused by penicillinase producing organism.
Examples: a.) Nafcillin sodium
                  b.) Cloxacillin
2. Aminopenicillins
            -increased effectiveness against gram negative organism.
Examples: a.) Ampicillin
                  b.) Amoxicillin
                  c.) Bacampicillin
3. Extended-spectrum penicillins
           -structurally similar to ampicillin but have an increased spectrum of activity against gram-negative bacteria.
Examples: a.) Carbenicillin sodium
                  b.) Piperacillin
4. Penicillin / beta-lactamase inhibitor combinations
            -prevents destruction of penicillin by enzymes and extend the penicillin’s spectrum of antimicrobial activity.
Examples: Amoxicillin / potassium clavulanate (Augmentin) Ampicillin/ Sulbactam (Unasyn)


C.   CEPHALOSPORINS divided into 4 generations based on their spectrums of activity.

Prototype for first generation (ephalozorines- Cefazolin Sodium (Ancef)
Action: Inhibits bacterial cell wall synthesis; bactericidal.
Use: infection caused by gram-positive cocci; septicemia; serious intraabdominal infection.
Adverse Effect: Phlebitis at IV site; diarrhea, pseudomembranous colitis, hypersensitivity, fungal overgrowth, discomfort at IM injection site, nephrotoxicity, hepatoxicity, bone marrow depression.

Nursing Implications:
1. Assess for hx of penicillin allergy as there is a cross allergy between cephalosporin and penicillin.
2. Dose will be reduced with renal and liver impairment
3. Probenecid therapy will increase blood levels of cephalosporin.

Related drugs:
a.)   Cephalexin (keflex)
b.)   Cephradine (Valosef)

Prototype for 2nd generation Cephalosporins –Cefoxitin Sodium (Mefoxin)
Action: same as above
Use: infection caused by gram-negative and gram-positive bacteria; septicemia, pelvic skin soft tissue infections, prophylaxis in abdominal or pelvic surgery; gonorrhea.
Adverse Effect: same as above

Nursing Implications: Lidocaine is used as diluent for IM injection and helps reduced pain of IM injection.

Related drugs:
a.)   Cefaclor (Ceclor)
b.)   Cefuroxime sodium
c.)   Cefrozil

Prototype for 3rd generation Cephalosporins –Cefotaxime (Claforan)
Use: Serious infections caused by gram-negative and gram-positive bacteria

Nursing Implication: Don’t mix with aminoglycoside solutions; protect IV solution from light.

Related drugs:
a.)   Ceftazidime
b.)   Ceftriaxone
c.)   Cefixine
d.)   Cefoperazone
e.)   Cefpodoxime
f.)     Ceftibuten

Prototype for 4th generation Cephalosporins –Cefepine (maxipene)
Use: UTI caused by E. coli or klebsiella pneumonia caused by streptococcus pneumoniae Pseudomonas acryinosa or enterobacter.

Nursing Implication: have vit. K available if hypoprothombinemia develops.

Related Drug: Cefditoren


D.  MACROLIDES

Prototype: Erythromycin
Action: Inhibits protein synthesis in bacterial cell, bacteriostatic.
Use: person allergic to penicillin, legionnaires Disease, mycoplasma pneumonia, intestinal dysenteric amebiasis, acne, staphylococcal and streptococcal infections.
Adverse Effect: G.I irritation, superintations, allergic reactions, hepatitis, reversible hearing loss.

Nursing Implications:
-Take on empty stomach with a full glass of water.
-G.I symptoms are dose related
-do not give with acids
-IV must be diluted sufficiently and administered slowly to avoid venous irritation and thrombophlebitis.

Related drugs:
1.)   Erythromycin estolate (Ilosone)
2.)   Azithromycin (Zithromax)
3.)   Clarithromycin (Biaxin)
4.)   Dirithromycin (Dynabac)


E.  TETRACYCLINES

Prototype: Tetracycline hydrochloride (Acromycin V)
Action: broad-spectrum with bateriostatic action and, at higher doses, bactericidal action; inhibits bacterial wall synthesis, reduces free fatty acids from triglycerides thus reducing acne lesions
Use: Chlamydia, mycoplasma, rickettsia, acne vulgaris, gonorrhea, spirochetes
Adverse Effect: hypersensitivity, superinfection chelating to teeth and new bome, N/V, diarrhea, colitis, headache, dizziness, abdominal cramping, photosensitivity.

Nursing Implications:
a.)   Avoid use during pregnancy, in nursing women, and in children under age 8 as drug binds to calcium in teeth and new bone growth, which results in tooth discoloration of permanent teeth and retarded bone growth
b.)   Give deep IM

Discharge Teaching:
a.)   Take 1hr. before or 2 hrs. After meals and avoid taking with dairy products, antacids, vitamins and minerals.
b.)   Avoid the sun while taking drug and for a few days after therapy is terminated
c.)   Use meticulous hygiene to reduce super infections.

Related Drugs:
  1. Doxycycline (Vibramycin) –can be administered with food.
  2. Minocycline (Minocin) –can be taken with food. Dizziness and fatigue may occur.
  3. Demeclocycline (Declomycin) –administer on an empty stomach; foods high in calcium and iron interfere with absorption.
F.  CHLORAMPHENICOL

Prototype: Chloramphenicol (Chloramycetin)
Action: a synthetic broad-spectrum agent primarily bacteriostatic but is bactericidal in higher dose; inhibits protein synthesis
Use: Haemophilus influenzae meningitis, rickettsia, salmonella typhi, mycoplasma, bactereoides, typoid fever.
*Chloramphenicol is used only in severe infections when other antibiotics can not be used due to its severe adverse effect of aplastic anemia.
*Gray baby syndrome: abdominal distention, vomiting, pallor, irregular respiration; circulatory collapse.
Adverse Effect: Aplastic Anemia; neurotoxicity; gray baby syndrome (seen in premature infants, newborn and children less than 2yrs old), hypersensitivity, N&V, enterocolitis, superinfections, bitter taste especially after IV injection.

Nursing Implications: Do not give by IM injection
Discharge Teaching: 1.) inform physician immediately of fever, fatigue, sore throat, or bruising.
2.) Take drug on empty stomach unless upset.


G.  SULFONAMIDES

Prototype: Sulfisoxazole (Gantrisin)
Action: prevents conversion of para-amino benzoic acid (PABA) to folic acid, which is required for bacterial growth; bacteriostatic, can be bactericidal in high urinary concentrations
Use:  UTI, Otitis media, nocardiosis, vaginitis
Adverse effects: hypersensitivity, Sterens-Johnson syndrome (acute onset of fever,bullae on skin and ulcers in mucous membranes of lips, eyes, mouth, nasal passages, and genetalia, pneumonia, joint pain ad prostratin are also seen fever 7 to 10 days after starting therapy may indicate  sensitization or hemolytic anemia; renal dysfunction hematologic reaction, G.I reaction; photosensitivity

Nursing Implications: Give oral form on empty stomach with full glass of water.
Discharge Teaching:
a.)   avoid direct sunlight
b.)   increased hypoglycemic reactions for patients taking OHA
c.)   Oral contraceptives may be unreliable while client is receiving sulfonamides.

Related drugs:
1.)   Sulfasalazine (Azulfidine)-used in treatment of ulceratives colitis, constains aspirin, so it is contraindicated in clients allergic to salicylates.
2.)   Sulfamethoxazole-can be given in combination with trimethoprim. (bactrim)-used in treatment of UTI, bronchitis, pneumocystis pneumonia.


H.  URINARY ANTI-INFECTIVES

1. Methenamine (mandelamine)
        -converted to formaldehyde (which is bactericidal) in the presence of acidic urine
Adverse Effect: N&V, diarrhea
Nursing Implications: -give with food
-avoid foods, fluids, and medications that alkalinize urine

2. Nalidixic Acid (Neg Gram)
        -bactericidal effect in gram-negative bacteria by preventing transmission of genetic informations.
Adverse Effect: Photosensitivity, headache, dizziness
Nursing Implication: give with food.

3. Nitrofurantoin (Macrodantin)
        -interferes with carbohydrates metabolism of bacteria; bacteriostatic in low concentration, and bactericidal in high concentrations.


I.  VANCOMYCIN
Prototype: Vancomycin hydrochloride (Vancocin)
Action: interferes with cell membrane synthesis and exhibits a bactericidal and bacteriostatic effect.
Use: staphylococcus infections, pseudomembranous colitis, grain positive organism s, penicillin and methicillin resistant bacteria
Adverse Effect: Ototoxicity, nephrotoxicity, hypersensitivity, thrombophlebitis, red-neck syndrome: (flushing and hypotension from rapid infusion), superifection.


J.  FLUOROQUINOLONES
Prototype: Ciprofloxacin (Cipro)
Actions: Inhibits DNA-syrase (an enzymes needed for replication of bacterial DNA) bactericidal
Use: pseudomonas infections, gram-negative urinary tract infections or gram-negative systemic infections
Adverse Effect: N&V, diarrhea, headache, tremors

Nursing Implications:
a.)   administer with a large glass of water to prevent crystalluria
b.)   Do not give with antacids.
c.)   Give 2hrs after meals.

Related drugs:
  1. Norfloxacin
  2. Gatifloxacin (Tequin)
  3. Leofloxacin
  4. Sparfloxacin (Zagam)
  
K.  ANTITUBERCULAR DRUGS

Prototype: Isoniazid (INH)
Action: Bacteriostatic and in high concentration becomes bactericidal
Use: initial treatment of tuberculosis; prophylactic treatment of tuberculosis in high risks group.
Adverse Effect: peripheral neuritis, jaundice, nausea, blood dyscrasis

Nursing Implications: give vit B6; on empty stomach, tyramine rich foods should be avoided; avoid histamine-containing foods as they may cause an exaggerated drug response; avoid alcohol

Related drugs:
1.) Ethambutol
Adverse Effect: optic neuritis, a loss of red green color discrimination, and decreased visual acuity can occur with dosages of 250mg
2.) Rifampicin –body fluids may turn orange.
3.) Streptomycin –damage to cranial nerve VIII
                           -renal toxicity
4.) Pyrazinamide –excess uric acid levels, w/c can cause gout or hepatic.
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