Classifications: beta-lactam antibiotic; natural penicillin;
Therapeutic: antibiotic
; beta-lactam
Prototype: Penicillin G potassium
Pregnancy Category: B


600,000 units/mL, 300,000 units/mL


Long-acting form of penicillin G. The procaine salt has low solubility and thus creates a tissue depot from which penicillin is slowly absorbed. Onset of action is slower and produces lower serum concentrations than penicillin G potassium, but has longer duration of action. It inhibits the final stage of bacterial cell wall synthesis by binding to specific penicillin-binding proteins (PBPs) located in the bacterial cell wall. This results in cell death of bacteria.

Therapeutic Effect

Same actions and antibacterial activity as for penicillin G potassium and is similarly inactivated by penicillinase and gastric acid.


Moderately severe infections due to penicillin G-sensitive microorganisms that are susceptible to low but prolonged serum penicillin concentrations. Commonly, uncomplicated pneumococcal pneumonia, uncomplicated gonorrheal infections, and all stages of syphilis. May be used concomitantly with penicillin G or probenecid when more rapid action and higher blood levels are indicated.


History of hypersensitivity to any of the penicillins, or to procaine or any other "caine-type" local anesthetic; lactation.

Cautious Use

History of or suspected allergy, hypersensitivity to cephalosporins, carbapenem; asthmatics; GI disease, renal disease; renal impairment; pregnancy (category B); infants, neonates.

Route & Dosage

Moderate to Severe Infections
Adult: IM 600,000–1,200,000 U once/d
Child: IM 300,000 U once/d

Pneumococcal Pneumonia
Adult: IM 600,000 U q12h

Uncomplicated Gonorrhea
Adult: IM 4,800,000 U divided between 2 different injection sites  at one visit preceded by 1 g of probenecid 30 min before injections

Adult: IM Primary, secondary, latent: 600,000 U/d for 8 d; late latent, tertiary, neurosyphilis: 600,000 U/d for 10–15 d
Child: IM 500,000–1,000,000 U/m2 once/d


  • Shake multiple-dose vial thoroughly before withdrawing medication to ensure uniform suspension of drug.
  • Use 20-gauge needle to avoid clogging.
  • Give IM deep into upper outer quadrant of gluteus muscle; in infants and small children midlateral aspect of thigh is generally preferred. Select IM site carefully. Accidental injection into or near major peripheral nerves and blood vessels can cause neurovascular damage.
  • Aspirate carefully before injecting drug to avoid entry into a blood vessel. Inadvertent IV administration reportedly has resulted in pulmonary infarcts and death.
  • Inject drug at a slow, but steady rate to prevent needle blockage. Give in two sites if the dose is very large. Rotate injection sites.

Adverse Effects (≥1%)

Body as a Whole: Procaine toxicity [e.g., mental disturbances (anxiety, confusion, depression, combativeness, hallucinations), expressed fear of impending death, weakness, dizziness, headache, tinnitus, unusual tastes, palpitation, changes in pulse rate and BP, seizures]. Also see PENICILLIN G POTASSIUM.


Drug: Probenecid decreases renal elimination; may decrease efficacy of oral contraceptives.


Absorption: Slowly from IM site. Peak: 1–3 h. Duration: 15–20 h. Distribution: Crosses placenta; distributed into breast milk. Metabolism: Hydrolyzed to penicillin in body. Elimination: By kidneys within 24–36 h.

Nursing Implications

Assessment & Drug Effects

  • Obtain an exact history of patient's previous exposure and sensitivity to penicillins, cephalosporins, and to procaine, and other allergic reactions of any kind prior to treatment.
  • Test patient by injecting 0.1 mL of 1–2% procaine hydrochloride intradermally if sensitivity is suspected. Appearance of a wheal, flare, or eruption indicates procaine sensitivity.
  • Be alert to the possibility of a transient toxic reaction to procaine, particularly when large single doses are administered. The reaction manifested by mental disturbance and other symptoms (see ADVERSE EFFECTS) occurs almost immediately and usually subsides after 15–30 min.

Patient & Family Education

  • Report any skin reaction at the site of injection.
  • Report onset of rash, itching, fever, chills or other symptoms of an allergic reaction to physician.

Common adverse effects in italic, life-threatening effects underlined; generic names in bold; classifications in SMALL CAPS; Canadian drug name; Prototype drug

© 2006-2023 Last Updated On: 01/27/2023 (0)
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