• Treatment of a wide variety of infections including:
  • Pneumococcal pneumonia,
  • Streptococcal pharyngitis,
  • Syphilis,
  • Gonorrhea strains.
• Treatment of enterococcal infections (requires the addition of an aminoglycoside).
• Prevention of rheumatic fever.
• Should not be used as a single agent to treat anthrax.

Unlabeled Uses:

• Treatment of Lyme disease.
• Prevention of recurrent Streptococcal pneumoniae septicemia in children with sickle-cell disease.

Contraindicated in:

• Previous hypersensitivity to penicillins (cross-sensitivity exists with cephalosporins and other beta-lactam antibiotics)
• Some products may contain tartrazine and should be avoided in patients with known hypersensitivity.

Use Cautiously in:

• Severe renal impairment (dosage ↓ recommended)
• OB: Use during pregnancy only if potential maternal benefit justifies potential fetal risk
• Lactation: Safety not established in lactation
• Geri: Consider ↓ body mass, age-related ↓ in renal/hepatic/cardiac function, concurrent diseases and drug therapy in older adults.

Derm: rash, urticaria.

GI: diarrhea, epigastric distress, nausea, vomiting, Clostridioides difficile-associated diarrhea (CDAD).

GU: interstitial nephritis.

Hemat: eosinophilia, leukopenia.

Neuro: SEIZURES.
Misc: (INCLUDING ANAPHYLAXIS AND SERUM SICKNESS) HYPERSENSITIVITY REACTIONS , superinfection.

Drug-Drug:

• Penicillin may ↓ effectiveness of oral contraceptive agents.
• Probenecid ↓ renal excretion and ↑ blood levels of penicillin (therapy may be combined for this purpose).
• Neomycin may ↓ absorption of penicillin.
• Concurrent use with methotrexate ↓ methotrexate elimination and ↑ risk of serious toxicity.

(Generic available)

• Tablets: 250 mg; 500 mg;
• Powder for oral solution: 125 mg/5 mL; 250 mg/5 mL;

• PO (Adults and Children ≥12 yr): Most infections: 125–500 mg every 6–8 hr. Rheumatic fever prevention: 125–250 mg every 12 hr.
• PO (Children <12 yr): Lyme disease: 50 mg/kg/day in 4 divided doses (unlabeled); prevention of Streptococcus pneumoniaesepsis in children with sickle cell disease—125 mg twice daily.

• Bind to bacterial cell wall, resulting in cell death.

• Bactericidal action against susceptible bacteria.

Spectrum:

• Active against:
  • Most gram-positive organisms, including many streptococci (Streptococcus pneumoniae, group A beta-hemolytic streptococci), staphylococci (non–penicillinase-producing strains) and Bacillus anthracis,
  • Some gram-negative organisms, such as Neisseria meningitidis and N. gonorrhoeae (only penicillin susceptible strains),
  • Some anaerobic bacteria and spirochetes including Borellia burgdorferi.

Therapeutic Classification: anti-infectives

Pharmacologic Classification: penicillins

Absorption: Variably absorbed from the GI tract. Resists acid degradation in the GI tract.

Distribution: Widely distributed, although CNS penetration is poor in the presence of normal (non-inflamed) meninges. Crosses the placenta and enters breast milk.

Protein Binding: 60%.

Metabolism/Excretion: Minimally metabolized by the liver, excreted mainly unchanged by the kidneys.

Half-life: 30–60 min.

Pen VK

(blood levels)

• Instruct patient to take medication around the clock and to finish drug completely as directed, even if feeling better. Advise patient that sharing this medication may be dangerous.
• Advise patient to report signs of superinfection (black, furry overgrowth on tongue; vaginal itching or discharge; loose or foul-smelling stools) and allergy.
• Instruct patient to notify health care professional if fever and diarrhea develop, especially if stool contains blood, pus, or mucus. Advise patient not to treat diarrhea without consulting health care professional.
• Instruct patient to notify health care professional if symptoms do not improve.
• Advise patient taking oral contraceptives to use an additional nonhormonal method of contraception during therapy with penicillin and until next menstrual period.
• Patient with an allergy to penicillin should be instructed to always carry an identification card with this information.

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