Penicillins

Penicillins

Drug monograph · NCLEX study reference
Trade names	Augmentin, Zosyn
Therapeutic class	Antibacterial
Pharmacologic class	Beta-lactam (penicillins, some with a beta-lactamase inhibitor)
Onset / peak / duration	Rapid; dosed multiple times daily by short half-life.
Half-life / level	Short half-life (about 0.5 to 1.5 hours); no routine level.
Routes	PO (oral), IV
High-alert (ISMP)	No
Black box warning	None
Antidote / reversal	Epinephrine and supportive care for anaphylaxis.
Pregnancy / lactation	Generally considered safe and commonly used.

Nursing pharmacology study reference (NCLEX-style monograph). Numeric values are standard teaching ranges for study and must be verified against current manufacturer labeling before clinical use. This is educational content, not prescribing guidance.

Penicillins (brand names Augmentin, Zosyn) — Antibacterial; Beta-lactam (penicillins, some with a beta-lactamase inhibitor).

Identification

• Therapeutic class: Antibacterial.
• Pharmacologic class: Beta-lactam (penicillins, some with a beta-lactamase inhibitor).

Pharmacology

• Mechanism of action: Bind penicillin-binding proteins to inhibit bacterial cell wall synthesis, causing cell lysis (bactericidal).
• Onset / peak / duration: Rapid; dosed multiple times daily by short half-life.
• Half-life / therapeutic level: Short half-life (about 0.5 to 1.5 hours); no routine level.

Clinical use

• Indications: Streptococcal infections, syphilis (penicillin G), otitis and respiratory and urinary infections (amoxicillin), broad and resistant infections (amoxicillin/clavulanate, piperacillin/tazobactam), staphylococcal infections (nafcillin, dicloxacillin).
• Usual dose, route, frequency: Amoxicillin PO two to three times daily; piperacillin/tazobactam and many others IV every 6 to 8 hours.
• Maximum dose / adjustments: Reduce dose in renal impairment for most; nafcillin is hepatically cleared.

Safety

• Contraindications: Penicillin or cephalosporin hypersensitivity (cross-reactivity).
• Black box warning: None.
• Interactions: Probenecid (raises levels), oral contraceptives (possible reduced effect), warfarin, allopurinol (rash with amoxicillin); food reduces some absorption.
• Pregnancy / lactation: Generally considered safe and commonly used.
• High-alert: No.

Adverse effects

• Common side effects: Diarrhea, nausea, rash.
• Serious effects to report: Anaphylaxis, severe rash, C. difficile colitis, seizures at very high doses in renal failure.
• Antidote / reversal: Epinephrine and supportive care for anaphylaxis.

Nursing process

• Assessment before administration: Allergy history, cultures, renal function.
• Interventions during therapy: Observe after the first dose for allergic reaction; complete the full course.
• Monitor: Signs of allergy, renal function, infection resolution, superinfection.
• Evaluation / expected outcome: Resolution of infection.

Patient teaching

• Patient teaching: Finish all doses; report rash or breathing difficulty; use backup contraception.
• Notify provider if: Rash, hives, wheezing or throat tightness, watery or bloody diarrhea.
• Administration tips: Amoxicillin with or without food; take on schedule; report allergy promptly.