Penicillin Flashcards

Questions and Answers

To what classification of drug does penicillin belong?

Antiviral drugs

Antifungal drugs

Antimicrobial drugs (correct)

Antibacterial drugs

Define β-lactamase.

β-lactamase is a bacterial enzyme that hydrolyzes the amide bond of the β-lactam ring.

What are penicillin-binding proteins (PBPs)?

Enzymes involved in the synthesis of the bacterial cell wall.

What are transpeptidases?

Bacterial enzymes responsible for cross-linking peptidoglycan chains. Signup and view all the answers

What is the major mechanism by which penicillins kill bacteria?

Penicillins bind to PBPs and inhibit the transpeptidase step. Signup and view all the answers

What additional mechanism is involved in the action of penicillins?

Penicillins release autolysins. Signup and view all the answers

Which type of organisms are not susceptible to penicillins?

Organisms that are not actively growing or do not have a cell wall. Signup and view all the answers

Do penicillins readily enter the central nervous system?

False Signup and view all the answers

How are the penicillins classified?

Natural penicillins, antistaphylococcal penicillins, antipseudomonal penicillins, extended-spectrum penicillins. Signup and view all the answers

Match the following natural penicillins with their routes of administration:

Penicillin G = Oral, intravenous, intramuscular Penicillin V = Oral only Penicillin G procaine = Intramuscular only Penicillin G benzathine = Intramuscular only Signup and view all the answers

How do the various natural penicillins differ from each other?

They differ in their route of administration and stability to gastric acid. Signup and view all the answers

What can natural penicillin be used for?

It affects gram-positive organisms, used for infections like streptococci, meningococci, and syphilis. Signup and view all the answers

Describe the absorption of these penicillins.

Absorption depends on their acid stability and protein binding. Signup and view all the answers

Is the absorption of penicillins influenced by food?

True Signup and view all the answers

How are these drugs excreted?

Mostly unchanged in the urine, some undergo hepatic inactivation. Signup and view all the answers

How can excretion of penicillins be altered?

By co-administration of probenecid, inhibiting organic acid secretion. Signup and view all the answers

What are the most common adverse effects seen with patients who are medicated with penicillin?

Hypersensitivity reactions, seizures, gastrointestinal disturbances, and cation toxicity. Signup and view all the answers

Are there adverse effects seen with all forms of penicillins?

True Signup and view all the answers

Study Notes

Antimicrobial Classification

Penicillin belongs to the β-lactams class of antimicrobial drugs, characterized by a four-membered lactam ring.

β-lactamase Enzyme

β-lactamase, also known as penicillinase, is a bacterial enzyme that hydrolyzes the β-lactam ring’s amide bond.

Penicillin-binding Proteins (PBPs)

PBPs are essential enzymes for bacterial cell wall synthesis and maintenance of bacterial morphology.

Transpeptidases

Transpeptidases are enzymes that cross-link peptidoglycan chains, a key step in bacterial cell wall synthesis.

Mechanism of Action

Penicillins kill bacteria by binding to PBPs and inhibiting transpeptidase, leading to bacterial lysis.

Role of Autolysins

Penicillins trigger the release of autolysins, which assist in normal bacterial cell wall remodeling.

Organism Susceptibility

Organisms that are not actively growing or lack a cell wall are not susceptible to penicillins.

Central Nervous System Distribution

Penicillins typically do not penetrate the central nervous system (CNS) well, but can reach therapeutic levels during meningitis.

Classification of Penicillins

Types of penicillins include:
- Natural penicillins
- Antistaphylococcal penicillins
- Antipseudomonal penicillins
- Extended-spectrum penicillins

Natural Penicillins and Administration Routes

Examples of natural penicillins:
- Penicillin G: oral, intravenous, intramuscular
- Penicillin V: oral only
- Penicillin G procaine: intramuscular only
- Penicillin G benzathine: intramuscular only

Variations in Natural Penicillins

Natural penicillins differ in routes of administration and gastric acid stability but share the same mechanism of action.

Clinical Uses of Natural Penicillin

Natural penicillin is effective mainly against gram-positive bacteria, indicated for infections like:
- Streptococci
- Meningococci
- Clostridium
- Listeria
- Enterococci
- Diphtheria
- Anthrax
- Syphilis
- Treponema pallidum
- Actinomycosis
- Bacteroides species (except fragilis)
- Anaerobic organisms without β-lactamase production

Absorption Characteristics

Absorption is influenced by acid stability and protein binding.

Food Interactions

Food impacts the absorption of most penicillins; they should be taken 1 to 2 hours before or after meals, except for amoxicillin.

Excretion Mechanism

Penicillins are primarily excreted unchanged in urine through glomerular filtration and active tubular secretion; some undergo hepatic inactivation.

Altering Excretion

Co-administration of probenecid can delay renal tubular secretion of penicillins.

Common Adverse Effects

Adverse effects of penicillins may include:
- Hypersensitivity reactions (anaphylaxis, urticaria, bronchospasm)
- Seizures (in patients with renal impairment)
- Gastrointestinal disturbances (diarrhea)
- Hemolytic anemia
- Cation toxicity due to excess sodium or potassium from high doses

Universal Toxicity

Adverse effects apply to all penicillin forms, not limited to natural varieties.

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Description

Test your knowledge on penicillin and its classifications with these flashcards. This quiz covers essential terms like β-lactams and β-lactamase, providing a concise review of key concepts in antimicrobial drugs. Perfect for students studying pharmacology or microbiology.