penicillin G


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penicillin

 [pen″ĭ-sil´in]
any of a large group of natural or semisynthetic antibacterial antibiotics derived directly or indirectly from strains of fungi of the genus Penicillium and other soil-inhabiting fungi grown on special culture media. Penicillins exert a bacteriocidal as well as a bacteriostatic effect on susceptible bacteria by interfering with the final stages of the synthesis of peptidoglycan, a substance in the bacterial cell wall. Despite their relatively low toxicity for the host, they are active against many bacteria, especially gram-positive pathogens (streptococci, staphylococci, pneumococci); clostridia; certain gram-negative forms (gonococci and meningococci); certain spirochetes (Treponema pallidum and T. pertenue); and certain fungi. Certain strains of some target species, for example staphylococci, secrete the enzyme penicillinase, which inactivates penicillin and confers resistance to the antibiotic. Some of the newer penicillins, such as methicillin, are more effective against penicillinase-producing organisms. A class of extended-spectrum penicillins includes piperacillin and mezlocillin.

Penicillin is administered intramuscularly, orally, in liquid or tablet form, and topically in ointments. Oral administration requires larger doses of the drug because absorption is incomplete. Allergic reactions occur in some persons. The reaction may be slight—a stinging or burning sensation at the site of injection—or it can be more serious—severe dermatitis or even anaphylactic shock, which may be fatal.
penicillin G the most widely used penicillin, used principally in the treatment of infections due to gram-positive organisms, gram-negative cocci, Treponema pallidum and Actinomyces israelii. The usual forms are salts such as penicillin benzathine, potassium, procaine, or sodium. Called also benzylpenicillin.
penicillin V a biosynthetically or semisynthetically produced antibiotic similar to penicillin g, used orally in the form of the benzathine or potassium salt for mild to moderately severe infections due to susceptible gram-positive bacteria.

pen·i·cil·lin G

a commonly used penicillin compound; it comprises 85% of the penicillin salts: sodium, potassium, aluminum, and procaine, with the latter exerting prolonged action on intramuscular injection, because of limited solubility. An antibiotic obtained from the mold Penicillium chrysogenum used orally and parenterally; primarily active against gram-positive staphylococci and streptococci; destroyed by bacterial β-lactamase.

penicillin G

n.
The most common component of most penicillin preparations, used usually in the form of its stable salts, and injected to treat infections caused primarily by gram-positive bacteria. Also called benzylpenicillin.

pen·i·cil·lin G

(peni-silin)
A commonly used penicillin compound; it comprises 85% of the penicillin salts: sodium, potassium, aluminum, and procaine, with the latter exerting prolonged action on intramuscular injection, because of limited solubility. An antibiotic obtained from the mold Penicillium chrysogenum used orally and parenterally; primarily active against gram-positive staphylococci and streptococci; destroyed by bacterial β-lactamase.

pen·i·cil·lin G

(peni-silin)
Common penicillin compound used orally and parenterally in dentistry and general medicine, primarily active against gram-positive staphylococci and streptococci.
Synonym(s): benzylpenicillin.

penicillin

any of a large group of natural or semisynthetic antibacterial antibiotics derived directly or indirectly from strains of fungi of the genus Penicillium and other soil-inhabiting fungi grown on special culture media. Penicillins exert a bactericidal as well as a bacteriostatic effect on susceptible bacteria by interfering with the final stages of the synthesis of peptidoglycan, a substance in the bacterial cell wall. Despite their relatively low toxicity for the host, they are active against many bacteria, especially gram-positive pathogens (streptococci, staphylococci); clostridia; certain gram-negative forms; certain spirochetes (Treponema pallidum and T. pertenue); and certain fungi. Certain strains of some target species, for example staphylococci, secrete the enzyme penicillinase, which inactivates penicillin and confers resistance to the antibiotic. Some of the newer penicillins, for example methicillin, are more effective against penicillinase-producing organisms. An additional class of extended-spectrum penicillins has been approved for use; it includes piperacillin and mezlocillin.
There are four groups of penicillins, the natural penicillins, penicillin G and penicillin V, with a narrow spectrum of activity, mainly against gram-positive bacteria; the aminopenicillins (amoxicillin, ampicillin and hetacillin) are semisynthetic derivatives and have a broad spectrum of activity against gram-positive and many gram-negative organisms, but are susceptible to penicillinase-producing Staphylococcus spp.; penicillinase-resistant penicillins, which include cloxacillin, methicillin, nafcillin and oxacillin; and the extended-spectrum penicillins (azlocillin, carbenicillin, mezlocillin, piperacillin and ticarcillin), which are effective against gram-positive and gram-negative organisms, including Pseudomonas aeruginosa.
Allergic reaction to penicillin occurs in some animals. The reaction may be slight—a stinging or burning sensation at the site of injection—or it can be more serious—severe dermatitis or even anaphylactic shock, which may be fatal.

penicillin allergy
degradation products of the penicillins act as haptens, binding to proteins and stimulating an immune response.
penicillin G
benzylpenicillin; the most widely used penicillin; used principally in the treatment of infections due to gram-positive bacteria. Procaine penicillin G is a parenteral preparation that gives extended action for up to 24 hours and benzathine penicillin G is a very slow-release, parenteral preparation that maintains blood levels for several days.
penicillin-induced hemolytic anemia
rare problem in horses which develop IgG anti-penicillin antibodies.
phenoxymethyl penicillin
a biosynthetically or semisynthetically produced antibiotic, similar to penicillin G, for oral administration; not affected by gastric acid and is suitable for oral administration. Its antibacterial spectrum is the same as for penicillin G. Called also penicillin V.
penicillin V
see phenoxymethyl penicillin (above).
References in periodicals archive ?
There is no shortage of oral or intramuscular formulations of penicillin G.
Physicians treating patients with conditions such as neurosyphilis, congenital syphilis, invasive group A streptococcal disease, or leprosy may purchase intravenous penicillin G on an "urgent need" basis, said Elizabeth Wheeler, director of communications for Geneva Pharmaceuticals.
Intravenous penicillin G is a first-line drug for syphilis, intrapartum group B streptococcal prophylaxis, invasive group A streptococcal disease, pneumococcal meningitis, penicillin-susceptible community-acquired pneumonia, endocarditis, and meningococcosis.
Paula Gaut, assistant medical director for the AIDS and Immune Disorder Center at Cedars-Sinai Medical Center in Los Angeles, said her institution has not yet run low on penicillin G.
Even in neurosyphilis patients who are allergic to penicillin, most physicians would prefer to follow a desensitization protocol and use penicillin G rather than try an unproven alternative, she said.
The current shortage of intravenous penicillin G began in June, when the largest generic supplier of the drug, Marsam Pharmaceuticals (a division of Schein Pharmaceuticals Inc.
quickly exhausted its own supplies of penicillin G, a problem exacerbated when the only FDA-approved supplier of sterile bulk penicillin G potassium went out of business.
There is no other FDA-approved source of penicillin G potassium in the world.
Meanwhile, a number of concerns have been raised about substituting other drugs for penicillin G, as suggested in a December report from the CDC.
The nonprofit Institute for Safe Medication Practices issued a warning in November 1999 about common errors involving penicillin G procaine and penicillin G benzathine as alternatives for penicillin G.
These problems are well-documented," the warning continued, citing a study by the National Association of Neonatal Nurses that showed 30%-35% of neonatal nurses and nurse-practitioners were unable to recognize the correct route of administration for penicillin G benzathine.
THERE HAVE BEEN REPORTS OF INADVERTENT INTRAVENOUS ADMINISTRATION OF PENICILLIN G BENZATHINE WHICH HAS BEEN ASSOCIATED WITH CARDIORESPIRATORY ARREST AND DEATH.