Overview of Anti-Infective Drugs and Their Uses

Penicillins

A class of narrow-spectrum antibiotics used to treat bacterial infections.

Penicillin G benzathine

An intramuscular (IM) formulation of penicillin used for treating infections.

Penicillin V

An oral (PO) formulation of penicillin used for treating infections.

Penicillin G potassium

An intravenous (IV) and intramuscular (IM) formulation of penicillin.

Mode of Action

Destroys bacteria by weakening the bacterial cell wall; considered a beta-lactam antibiotic.

Therapeutic Use

Treats gram-positive cocci infections, including pneumonia, meningitis, and pharyngitis.

Adverse Effects/Complications

Includes allergies and anaphylaxis; monitor for allergic reactions.

Immediate Allergic Reaction

Occurs 2-30 minutes after administration.

Accelerated Allergic Reaction

Occurs 1-72 hours after administration.

Delayed Allergic Reaction

Occurs days to weeks after administration.

Renal Impairment

Monitor kidney function (creatinine, BUN) and I&O to assess renal function.

Electrolyte Imbalances

Hyperkalemia and dysrhythmias can occur with high doses of Penicillin G potassium.

Contraindications/Precautions

Contraindicated in clients with severe allergies to penicillin or cephalosporins.

Cross-allergy warning

Allergy to one penicillin means allergy to all penicillins.

Interactions

Penicillin inactivates aminoglycosides when mixed in the same IV solution.

Delayed Excretion with Probenecid

Probenecid delays penicillin excretion, prolonging its effects.

Nursing Intervention

Monitor for allergic reactions and instruct clients to report symptoms.

IM Injection Caution

Avoid injecting into nerves or arteries to prevent sensory/motor dysfunction.

Client Education for Penicillin V

Take with meals.

Client Education for Other Penicillins

Take with 8 oz water, 1 hour before or 2 hours after meals.

Completing Antibiotics

Complete the full course of antibiotics, even if symptoms resolve early.

Use of Additional Contraception

Penicillins can decrease the effectiveness of hormonal birth control.

Cephalexin

1st Generation cephalosporin available as capsules, tablets, and oral suspension.

Mode of Action of Cephalexin

Treats infections caused by gram-positive cocci.

Therapeutic Use of Cephalexin

Used to treat UTIs, post-op infections, pelvic infections, and meningitis.

Adverse Effects of Cephalexin

GI symptoms, Clostridium-difficile-associated diarrhea (CDAD)/C.diff, and possible cross-allergy to penicillin.

Contraindications for Cephalexin

Allergy to cephalosporin antibiotics or penicillin (possible cross-sensitivity).

Nursing Intervention for Cephalexin

Monitor and report blood stools or watery diarrhea; assess for cephalosporin or penicillin allergy before administration.

Client Education for Cephalexin

Take with food to decrease GI symptoms; report watery or blood diarrhea, unusual bruising or bleeding to the provider; do not drink alcohol.

Tetracycline

A protein synthesis inhibitor given orally on an empty stomach, 1 hour before or 2 hours after meals.

Therapeutic Use of Tetracycline

First antibiotic for Chlamydia, Mycoplasma, Rickettsial infections, gram-positive infections, cholera, and anthrax; treats acne vulgaris.

Adverse Effects of Tetracycline

GI symptoms, permanently discolored teeth in fetus and children, hepatotoxicity, superinfections, and photosensitivity.

Contraindications for Tetracycline

Pregnancy risk, children under 8 years, exposure to ultraviolet light, serious renal or liver failure.

Nursing Intervention for Tetracycline

Monitor and report GI symptoms, liver function tests, signs of superinfection, skin reactions, lymphadenopathy, and facial swelling.

Client Education for Tetracycline

Take with non-dairy foods if GI symptoms occur; report to provider if pregnant; wear protective clothing and sunscreen.

Ciprofloxacin

A fluoroquinolone antibiotic given orally and intravenously.

Mode of Action of Ciprofloxacin

Bactericidal due to inhibition of an enzyme necessary for DNA replication.

Therapeutic Use of Ciprofloxacin

Treats a wide range of bacterial infections including severe urinary tract disorders and prevents anthrax after inhalation.

Adverse Effects of Ciprofloxacin

Mild CNS symptoms, GI symptoms, Achilles tendon rupture, photosensitivity, and suprainfection.

Contraindications for Ciprofloxacin

Children under 18, tendon pain, and myasthenia gravis.

Interactions with Ciprofloxacin

Cationic compounds decrease absorption; plasma levels of theophylline and warfarin can increase with concurrent use.

Aminoglycoside

Gentamicin

Route of Aminoglycoside

Topical, Ophthalmic, IM/IV, Intrathecal forms

Mode of Action of Aminoglycosides

Aminoglycosides are bactericidal antibiotics that destroy micro-organisms by disrupting protein synthesis.

Therapeutic Use of Aminoglycosides

Gram-negative aerobic bacilli severe infections

Adverse Effects of Aminoglycosides

Ototoxicity and loss of balance, Nephrotoxicity, Respiratory depression, Rash

Contraindications for Aminoglycosides

Use with caution if known: Kidney disease, Liver disease, Myasthenia gravis

Interactions of Aminoglycosides

Penicillin inactivates aminoglycosides when in the same IV solution. Concurrent administration with other ototoxic medications increases the risk for ototoxicity.

Nursing Intervention for Aminoglycosides

Monitor for serum medication levels by measuring peak and troughs

Client Education for Aminoglycosides

Report onset: Tinnitus, Headache, Vertigo, Hearing loss, Increase in the output of dilute urine to the provider

Urinary Tract Analgesic

Phenazopyridine

Route of Phenazopyridine

PO

Mode of Action of Phenazopyridine

The medication is an azo dye that functions as a local anesthetic on the mucosa of the urinary tract.

Therapeutic Use of Phenazopyridine

Relieves Burning, Pain, Urgency, Frequency related to urinary tract irritation caused by infection, Trauma, Surgery

Adverse Effects of Phenazopyridine

Liver damage including: Hepatitis, Liver failure, Peripheral neuropathy, CNS symptoms, GI symptoms

Contraindications for Phenazopyridine

Acute kidney injury, Chronic kidney disease

Nursing Intervention for Phenazopyridine

Assess the client for urgency, frequency, and pain on urination before and throughout therapy

Client Education for Phenazopyridine

Changes urine color to orange and can stain clothes. Take with meals to minimize GI issues. Can cause dizziness. Educated to rise slowly initially.

Antimycobacterial

Isoniazid

Route of Isoniazid

Tablets, Oral syrup, IM

Mode of Action of Isoniazid

This medication is highly specific for mycobacteria. Isoniazid inhibits growth of mycobacteria by preventing synthesis of mycolic acid in the cell wall.

Therapeutic Use of Isoniazid

Treatment for active and latent tuberculosis (TB)

Adverse Effects of Isoniazid

Peripheral neuropathy, Hepatotoxicity, Hyperglycemia if the client is diabetic

Contraindications for Isoniazid

Severe liver damage from any cause

Interactions of Isoniazid

Isoniazid inhibits metabolism of phenytoin, leading to buildup of medication and toxicity.

Nursing Intervention for Isoniazid

Monitor for and report: GI symptoms, Signs of liver damage, Level of liver enzymes throughout therapy

Client Education for Isoniazid

Report jaundice, Abdominal pain, Unusual fatigue, Numbness, Tingling, Pain in hands or CNS symptoms to provider

Antifungal, polyene

Amphotericin B

Route of Amphotericin B

IV infusion, Oral (PO) suspension

Mode of Action of Amphotericin B

Amphotericin B is an antifungal agent that acts on fungal cell membranes to cause cell death.

Therapeutic Use

Treatment of severe systemic fungal infections: (candidiasis, aspergillosis, cryptococcosis, mucormycosis) and nonopportunistic mycoses.

Adverse Effects/Complications

Infusion reaction, Chills, Fever, Tachycardia, Hypotension, Headache, Nausea, Renal toxicity, Red blood cell suppression.

Contraindications/Precautions

Allergy to amphotericin, Lactation.

Interactions

Aminoglycosides (gentamicin, streptomycin, cyclosporine) have additive nephrotoxic risk when used concurrently with antifungal medications. Antifungal effects of flucytosine are potentiated with concurrent use of amphotericin B. Azole antibiotics increase levels of multiple medications, including digoxin, warfarin, and sulfonylurea antidiabetic medications.

Nursing Intervention

Administer prescribed diphenhydramine (Benadryl) and acetaminophen (Tylenol) before beginning infusion. Monitor vital signs and for symptoms during infusion.

Client Education

Be aware that infusion reaction may occur and notify staff for beginning symptoms. Comply with laboratory testing. Report increasing fatigue to the provider.

Antiprotozoal

Metronidazole.

Route (Metronidazole)

Tablets, capsules, sustained-release capsules, topical cream, vaginal gel, and IV infusion. Give oral dose 1 hour before or 2 hours after a meal for best absorption.

Mode of Action (Metronidazole)

Metronidazole is a broad-spectrum antimicrobial with bactericidal activity against anaerobic microorganisms.

Therapeutic Use (Metronidazole)

IV → treats anaerobic bacterial infections. Oral → treats some bacterial infections and protozoal infections.

Adverse Effects/Complications (Metronidazole)

GI symptoms, CNS symptoms, Darkening of urine, Anorexia, Dry mouth.

Contraindications/Precautions (Metronidazole)

Active CNS diseases, Pregnancy risk → teratogenic.

Interactions (Metronidazole)

Alcohol causes a disulfiram-like reaction (facial flushing, vomiting, dyspnea, tachycardia). Metronidazole inhibits inactivation of warfarin, phenytoin, and lithium.

Nursing Intervention (Metronidazole)

Monitor for and report: Severe GI symptoms, CNS symptoms.

Client Education (Metronidazole)

Take just before, with, or after a meal if GI symptoms occur. Instruct clients they may experience a metallic taste, Headache, Dizziness. Advise clients to avoid alcohol.

Antiviral

Acyclovir.

Route (Acyclovir)

Oral capsules and tablets, Oral liquid suspension, Topical cream and ointment, IV forms.

Mode of Action (Acyclovir)

Acyclovir and ganciclovir prevent the reproduction of viral DNA and thus interrupts cell replication.

Therapeutic Use

Treats herpes 1 and 2

Varicella-zoster virus

A virus that causes chickenpox and shingles.

Adverse Effects/Complications - Topical form

Burning, itching at application site

Adverse Effects/Complications - Oral

GI symptoms, headache, vertigo

Adverse Effects/Complications - IV

Renal toxicity, CNS toxicity, Thrombophlebitis

Contraindications/Precautions - Buccal form

Milk protein concentrate

Nursing Intervention

Monitor and report severe skin reactions

Nursing Intervention

Infuse IV form slowly

Nursing Intervention

Hydrate client during and for 2 hours following infusion to maintain urine output

Client Education

Instruct client that uses OTC lotion and creams may delay or alter the effectiveness of the treatment

Client Education

Instruct female clients with genital herpes to get a yearly pap smear

Nucleoside Reverse Transcriptase Inhibitor (NRTI)

Zidovudine