PENICILLIN

Introduction
• Penicillin was discovered in 1928 by Alexander Fleming, who noticed that one of his experimental cultures of staphylococcus was contaminated with mold, which caused the bacteria to lyse. Since mold belonged to the family Penicillium, he named the antibacterial substance penicillin.

Definition
• Penicillin are a group of antibiotics originally obtained from Penicillium moulds, principally P. chrysogenum and P. rubens.
• Penicillin's were among the first medications to be effective against many bacterial infections caused by staphylococci and streptococci.

Classification
Natural penicillin
This are naturally obtained from the fungi which is administered in the form of injection.
Example:
1. Benzothine penicillin
It has long duration of action that lasts for 12-24 hrs and is given to treat chronic infections. (Dosage 4 lakhs-10 lakhs, IM route).
2. Procaine penicillin G
It has short duration action that lasts for 4-6 hours and it is used to treat severe infections.(dosage 0.5-5 million units IM or IV route)
Semi synthetic penicillin:
These are penicillin obtained from fungi and coated with chemical substances to prevent it destroying from acid secretions of stomach.
Example:
Penicillin V, Phenoxy ethyl penicillin, Phenoxy propyl penicillin
Dosage: 50-150 mg IV or IM.

Synthetic Penicillin:
These are penicillin artificially made with chemical substance and enzymes called penicillinase. These are more effective than other penicillin.
Example: Methicillin, cloxacillin, oxacillin and nafcillin. Dosage 50-500mg IM or IV

Broad spectrum penicillin:
These are synthesized against gram positive and gram negative micro organisms.
Example: Ampicillin, Hetacillin, Carbenicillin. Dosage 50-500mg IM or IV

Mechanism of Action

Penicillin exert their bactericidal activity by binding the β-lactam ring to DD-trans peptidase enzyme
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Inhibition of cross-linking activity i.e. synthesis of peptidoglycans which is the structural component of bacteria
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Weakening of the bacterial cell wall

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Prevents bacterial new cell formation

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Without a cell wall, a bacterial cell is vulnerable to outside water and molecular pressures

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Causes the bacterial cell to quickly die i.e. bactericidal activity.

Pharmacokinetics:
• The drug is absorbed in the muscles and excreted in urine, in breast milk and crosses placenta.

Drug interaction:

• Penicillin’s decrease the effectiveness of oral contraceptives. It increases bleeding time.

Indications
• Pneumonia
• Streptococcal infection
• Meningococcal infection
• STD
• Syphilis
• Gonorrhea
• Diphtheria
• Tetanus

Contra Indications
• Avoid the drug if there is history of itching, urticaria, fever and sensitivity.

• Toxic Effects:
- Nephrotoxicity
- Anaphylactic shock
- Neurotoxicity
- Hypersensitivity.

Adverse  & Side-Effects
• Diarrhea, Nausea, vomiting, pseudo membranous colitis, GI upset
• Urticaria, skin rash, fever, erythema, dermatitis, angioedema, and super infection (candidiasis)
• Seizures (especially in people with epilepsy) and Anxiety
• Anemia and bone marrow depression.

Nursing Responsibility
• Assess for hematuria, oliguria, to identify Nephrotoxicity
• Monitor for signs of neurotoxicity like history epilepsy, level of consciousness etc.
• Administer test dose before giving the drug
• Perform complete blood study Red blood cell, White blood cell, Bleeding Time (BT), Clotting time (CT)
• Monitor Liver Function study like bilirubin and liver enzymes
• Monitor for Gastro Intestinal disturbances like diarrhea, nausea and vomiting
• Maintain intake and output chart
• Monitor allergic reactions and skin rash or Itching
• Instruct the client about hygienic practices to avoid super infection
• Evaluate therapeutic response treatment of infection.