Podcast
Questions and Answers
Which mechanism explains how phenicols inhibit protein synthesis in both eukaryotic and prokaryotic cells?
Which mechanism explains how phenicols inhibit protein synthesis in both eukaryotic and prokaryotic cells?
- Preventing transpeptidation by binding to the 30S ribosomal subunit.
- Interfering with tRNA binding to the ribosome.
- Inhibiting mRNA transcription.
- Preventing transpeptidation by binding to the 50S ribosomal subunit. (correct)
Why might dosage adjustments be necessary when administering phenicols to cats?
Why might dosage adjustments be necessary when administering phenicols to cats?
- Cats have increased renal clearance of the drug.
- Cats have a genetic deficiency in glucuronidase enzymes, leading to longer drug plasma half-lives. (correct)
- Cats have decreased drug absorption in the gastrointestinal tract.
- Cats have increased drug metabolism due to higher liver enzyme activity.
How do phenicols affect the duration of action of other drugs administered concurrently?
How do phenicols affect the duration of action of other drugs administered concurrently?
- They shorten the duration of action by accelerating renal clearance.
- They have no effect on the duration of action of other drugs.
- They shorten the duration of action by inducing hepatic enzymes.
- They prolong the duration of action by acting as non-competitive microsomal enzyme inhibitors. (correct)
Which of the following is the primary reason chloramphenicol is restricted in use in food-producing animals?
Which of the following is the primary reason chloramphenicol is restricted in use in food-producing animals?
What mechanisms do bacteria use to develop resistance to phenicols?
What mechanisms do bacteria use to develop resistance to phenicols?
What is the most likely consequence of administering chloramphenicol to a patient who is not properly vaccinated?
What is the most likely consequence of administering chloramphenicol to a patient who is not properly vaccinated?
What characteristic of distribution allows phenicols to be effective in treating infections of the central nervous system (CNS) and eye?
What characteristic of distribution allows phenicols to be effective in treating infections of the central nervous system (CNS) and eye?
A veterinarian needs to treat bovine respiratory disease in cattle. Which phenicol is most appropriate for this condition?
A veterinarian needs to treat bovine respiratory disease in cattle. Which phenicol is most appropriate for this condition?
What is the primary route of metabolism for phenicols in the body?
What is the primary route of metabolism for phenicols in the body?
A laboratory test reveals that a bacterium is resistant to tetracycline, streptomycin, and ampicillin. What can be inferred about its potential resistance to chloramphenicol?
A laboratory test reveals that a bacterium is resistant to tetracycline, streptomycin, and ampicillin. What can be inferred about its potential resistance to chloramphenicol?
In a non-ruminant animal treated with oral chloramphenicol, what is a potential adverse effect related to the gastrointestinal system?
In a non-ruminant animal treated with oral chloramphenicol, what is a potential adverse effect related to the gastrointestinal system?
Which of the following is a characteristic action of chloramphenicol at low concentrations?
Which of the following is a characteristic action of chloramphenicol at low concentrations?
Excluding food-producing animals, what types of infections can chloramphenicol treat?
Excluding food-producing animals, what types of infections can chloramphenicol treat?
What is the spectrum of activity of chloramphenicol?
What is the spectrum of activity of chloramphenicol?
Which of the following adverse effects relates to bone marrow suppression when administering chloramphenicol?
Which of the following adverse effects relates to bone marrow suppression when administering chloramphenicol?
A patient is diagnosed with a Salmonella infection. Which phenicol drug would be appropriate to treat this infection?
A patient is diagnosed with a Salmonella infection. Which phenicol drug would be appropriate to treat this infection?
How does acetylation contribute to bacterial resistance against phenicols?
How does acetylation contribute to bacterial resistance against phenicols?
What is a characteristic that makes Florfenicol suitable for use in cattle?
What is a characteristic that makes Florfenicol suitable for use in cattle?
What is the implication of decreased membrane permeability in bacteria concerning phenicol antibiotics?
What is the implication of decreased membrane permeability in bacteria concerning phenicol antibiotics?
Which of the following describes the distribution of phenicols within the body after administration?
Which of the following describes the distribution of phenicols within the body after administration?
Flashcards
Phenicols mechanism of action
Phenicols mechanism of action
Binds to the 50S ribosomal subunit, inhibiting both eukaryotic and prokaryotic protein synthesis, preventing transpeptidation.
Phenicols administration and distribution
Phenicols administration and distribution
Rapidly absorbed in the gastrointestinal tract and widely distributed, including the CNS and eye.
Phenicols in cats
Phenicols in cats
Cats have a genetic deficiency in glucuronidase enzymes, which leads to longer drug plasma half-lives; dosages need adjustment.
Phenicols metabolism
Phenicols metabolism
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Phenicols as enzyme inhibitors
Phenicols as enzyme inhibitors
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Adverse reactions to chloramphenicol
Adverse reactions to chloramphenicol
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Bacterial resistance to phenicols
Bacterial resistance to phenicols
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Chloramphenicol's therapeutic uses
Chloramphenicol's therapeutic uses
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Chloramphenicol restrictions
Chloramphenicol restrictions
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Florfenicol use
Florfenicol use
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Spectrum of activity of Phenicols
Spectrum of activity of Phenicols
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Study Notes
- Phenicols are toxic to both humans and animals
Names
- Chloramphenicol and Florfenicol are examples of phenicols, as indicated by the '-phenicol' suffix in their name
Mechanism of Action
- Binding to the 50S ribosomal subunit prevents transpeptidation
- Inhibits both eukaryotic and prokaryotic protein synthesis
- At low concentrations, phenicols are bacteriostatic; at high concentrations, they are bactericidal
Pharmacokinetics
- Administration allows for rapid absorption in the gastrointestinal tract
- Distribution is wide, including the central nervous system and the eye, where it accumulates
- Metabolism occurs through extensive hepatic glucuronide conjugation
- Cats have a genetic deficiency in glucuronidase enzymes, resulting in longer drug plasma half-lives; dosages need adjustment
- Phenicols function as non-competitive microsomal enzyme inhibitors, prolonging the action of other drugs
Adverse Reactions (Chloramphenicol)
- Bone marrow suppression may cause irreversible aplastic anemia, precluding use in food animals
- Bone marrow suppression may cause non-regenerative anemia
- Immunosuppressant properties caution against administration close to vaccination
- Oral chloramphenicol can cause gastrointestinal disturbances, particularly in nonruminant animals
Spectrum of Activity
- Effective against a broad spectrum of bacteria including Gram-positive, Gram-negative, and many anaerobes, especially Salmonella
Bacterial Resistance
- Acetylation of the phenicol prevents ribosome binding
- Decreased membrane permeability to chloramphenicol
- Resistance to chloramphenicol often occurs with resistance to other antibiotics, such as tetracycline, streptomycin, and ampicillin
Therapeutic Applications
- Chloramphenicol is used to treat both systemic and local infections caused by anaerobes and Salmonella species, affecting the respiratory system, central nervous system, and eyes
- Chloramphenicol use is restricted in production animals because it causes irreversible aplastic anemia
- Florfenicol is exclusively used in cattle to treat bovine respiratory disease
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