ANTIBIOTICS

Use the 'Back' button on your browser to return to previous page

Popular Brand Name

Dose/route:

• IM 400,000-600,000 units q6h.
• High doses are needed in order to maintain adequate serum levels since serum half-life is short.
• IM/oral (oral absorption is erratic; parenteral route is recommended, though chances
• of developing allergic reactions are increased).
• Therefore penicillin G is reserved for severe infections, or when the oral route is compromised (as in malabsorption syndrome and vomiting)

Drug action:

• Inhibits enzymes responsible for cell wall synthesis of susceptible organisms.
• This creates an osmotically unstable cell wall that swells and bursts from osmotic pressure.
• It is a bactericidal drug in normal doses.
• This drug is excreted through the renal system.

How supplied:

Available for IM injection:

• Aqueous crystalline penicillin G
• procaine penicillin G
• benzathine penicillin G

Spectrum covered:

• A narrow-spectrum antibiotic because at usual doses it mainly affects gram-positive aerobic and facultative microorganisms, some anaerobes, and spirochetes.
• Effective against anaerobes associated with dental and periodontal diseases of acute or chronic types: Diphtheroids, fusobacteria, peptostreptococci, spirochetes, Actinomyces, Veillonella, and some Bacteroides, Prevotella and Prophyromonas spp.
• Effective for gram- positive cocci (S. aureus, S. viridans, S. faecalis, S. bovis, S. pneumoniae), gram negative cocci (N. gonorrhoeae, N. memingitidis), gram-positive bacilli (B. anthracis, Clostridium. species), gram-negative bacilli (S. moniliformis), spirochetes (T. pallidum), Actinomyces, Peptococcus, Peptostreptococcus species.
• Penicillin G is slightly more effective against these organisms than is penicillin V that may be important in severe infections.

Indications:

Penicillin G is reserved for severe infections, or when the oral route is compromised (as in malabsorption syndrome and vomiting), and for some patients requiring prophylactic coverage.

Drug interactions:

Penicillins can decrease the effectiveness of oral contraceptives. Tetracyclines, erythromycins, lincomycins all decrease the antimicrobial effectiveness of penicillin. Aspirin, probenecid, and butazolidin may potentiate penicillin's effects. Penicillin may potentiate coumadin and tandearil effects.

Contraindications:

Patients with known allergies to penicillin, which is approximately 3% of the population. In patients with renal impairment, dosages should be decreased since excretion of drug is by the renal system. A different formulation should be used in these patients such as penicillin procaine that allows a slow release into the serum from the intramuscular site. Precaution with pregnancy category B, lactation, and hypersensitivity to cephalosporins.

Side effects:

The penicillins are among the least toxic drugs known. They rarely elicit adverse reactions in humans unless present in excessive concentrations. They can disrupt the normal gastrointestinal flora and cause nausea, vomiting, diarrhea, abdominal pain, colitis, and anorexia. To minimize diarrhea it is recommended that penicillin be taken with two to three tablespoons of yogurt, or a lactobacillum tablet. Fatal anaphylaxis is estimated to occur in one in 10,000 users. At high doses penicillin can have a toxic effect that can cause seizures, platelet dysfunction, hemolytic anemias of an immunologic type, encephalitis, and nephritis. Pseudomembraneous colitis is an occasional adverse reaction.

Gage,T., Pickett, F.: Mosby's dental drug reference. Mosby publishing, 1996.

Neidle, E., Yageila, J.: Pharmacology and therapeutics for dentistry. Mosby 3rd edition. 1989.

Newman, M., Kornman, K.: Antibiotic/antimicrobial use in dental pratice. Quintessence Publishing Co., Inc. 1990.