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 2^nd 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 3^rd 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 4^th 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.