Podcast
Questions and Answers
Amphotericin B is obtained from Streptomyces nodosus. Two types A & B but only B is used clinically because it is significantly more active in vivo. Amphotericin B is insoluble in water & is often used intravenously for systemic fungal infections. Rapidly decomposes on exposure to light. Mechanism of action The amphotericin B and other polyene antibiotics have high affinity for ______, present in fungal cell membranes.
Amphotericin B is obtained from Streptomyces nodosus. Two types A & B but only B is used clinically because it is significantly more active in vivo. Amphotericin B is insoluble in water & is often used intravenously for systemic fungal infections. Rapidly decomposes on exposure to light. Mechanism of action The amphotericin B and other polyene antibiotics have high affinity for ______, present in fungal cell membranes.
ergosterol
High concentration of amphotericin B directly disrupts the fungal cell membrane permeability and leakage of cellular contents. Amphotericin B is fungistatic at normal dosages, but it can become fungicidal at higher concentrations. Antimicrobial spectrum Amphotericin B have broad-spectrum antifungal against is useful against several systemic fungi including Candida, Histoplasma, Cryptococcus, Blastomyces, Coccidioides, Aspergillus and Sporithrix spp. Some algae and protozoa (e.g. Leishmania, Trypanosoma, Trichomonas and Entamoeba spp.) are sensitive to the polyene antibiotics. Amphotericin B is not effective against clinical ______.
High concentration of amphotericin B directly disrupts the fungal cell membrane permeability and leakage of cellular contents. Amphotericin B is fungistatic at normal dosages, but it can become fungicidal at higher concentrations. Antimicrobial spectrum Amphotericin B have broad-spectrum antifungal against is useful against several systemic fungi including Candida, Histoplasma, Cryptococcus, Blastomyces, Coccidioides, Aspergillus and Sporithrix spp. Some algae and protozoa (e.g. Leishmania, Trypanosoma, Trichomonas and Entamoeba spp.) are sensitive to the polyene antibiotics. Amphotericin B is not effective against clinical ______.
dermatophytosis
Polyene antibiotics obtain from actinomyces MOA: The polyenes bind to ______ in the fungal cell membrane and promote leakiness which may contribute to fungal cell death.
Polyene antibiotics obtain from actinomyces MOA: The polyenes bind to ______ in the fungal cell membrane and promote leakiness which may contribute to fungal cell death.
ergosterol
Amphotericin B and other polyene antibiotics have high affinity for ______, present in fungal cell membranes. High concentration of amphotericin B directly disrupts the fungal cell membrane permeability and leakage of cellular contents.
Amphotericin B and other polyene antibiotics have high affinity for ______, present in fungal cell membranes. High concentration of amphotericin B directly disrupts the fungal cell membrane permeability and leakage of cellular contents.
Signup and view all the answers
Amphotericin B is poorly absorbed from the GI tract and, therefore, oral used only for gastrointestinal fungal infection. For systemic infection, it is given by repeated daily slow IV injections because it is not absorbed after IM or other parenteral routes. It distributes very unevenly throughout the body & can not pass the CSF, vitreous humour and amniotic fluid. For fungal meningitis, it has to be given ________.
Amphotericin B is poorly absorbed from the GI tract and, therefore, oral used only for gastrointestinal fungal infection. For systemic infection, it is given by repeated daily slow IV injections because it is not absorbed after IM or other parenteral routes. It distributes very unevenly throughout the body & can not pass the CSF, vitreous humour and amniotic fluid. For fungal meningitis, it has to be given ________.
Signup and view all the answers
It is extensively bound to plasma lipoproteins, longer terminal half-life of about 15 days. Drug eliminate via ________ & bile.
It is extensively bound to plasma lipoproteins, longer terminal half-life of about 15 days. Drug eliminate via ________ & bile.
Signup and view all the answers
The nephrotoxicity generally occurs via two mechanisms intense renal vasoconstriction and binding of drug to membrane cholesterol in the renal tubular cell membrane. Other adverse effects includes anorexia, nausea, vomiting, anaemia, cardiac arrhythmias, CNS signs (if given intrathecally), hepatic dysfunctions and thrombophlebitis at injection site. Cats are more sensitive to the renal toxic effects. During the therapy monitored patient's renal function by urine analysis of ________ & creatinine.
The nephrotoxicity generally occurs via two mechanisms intense renal vasoconstriction and binding of drug to membrane cholesterol in the renal tubular cell membrane. Other adverse effects includes anorexia, nausea, vomiting, anaemia, cardiac arrhythmias, CNS signs (if given intrathecally), hepatic dysfunctions and thrombophlebitis at injection site. Cats are more sensitive to the renal toxic effects. During the therapy monitored patient's renal function by urine analysis of ________ & creatinine.
Signup and view all the answers
Amphotericin B is effective antifungal agent mainly in dogs & other spp. for serious life-threatening systemic infections. It is usually diluted in 5% dextrose and administered _________.
Amphotericin B is effective antifungal agent mainly in dogs & other spp. for serious life-threatening systemic infections. It is usually diluted in 5% dextrose and administered _________.
Signup and view all the answers
Nystatin is primarily used for skin, mouth, intestinal or vaginal candidiasis in dogs, cats and birds. Dose: Dogs : 50,000- 150,000 Units (total), PO, 3 times daily. Cats: 1,00,000 Units (total), PO, 4 times ________.
Nystatin is primarily used for skin, mouth, intestinal or vaginal candidiasis in dogs, cats and birds. Dose: Dogs : 50,000- 150,000 Units (total), PO, 3 times daily. Cats: 1,00,000 Units (total), PO, 4 times ________.
Signup and view all the answers
Natamycin is used to treat fungal infections, including Candida, Aspergillus, Cephalosporium, Fusarium and Penicillium. Used to treat fungal keratitis in eye infection. Mainly used ________.
Natamycin is used to treat fungal infections, including Candida, Aspergillus, Cephalosporium, Fusarium and Penicillium. Used to treat fungal keratitis in eye infection. Mainly used ________.
Signup and view all the answers
Study Notes
Amphotericin B Overview
- Derived from the bacterium Streptomyces nodosus.
- Two types exist: A and B, with B being clinically significant due to higher activity in vivo.
- Insoluble in water, commonly administered intravenously for systemic fungal infections.
Properties and Dosage
- Sensitive to light; rapid decomposition occurs upon exposure.
- Poorly absorbed from the gastrointestinal tract; oral usage is limited to gastrointestinal fungal infections.
- Administrated for systemic infection via repeated daily slow IV injections.
- Does not pass into the central nervous system (CSF), vitreous humor, or amniotic fluid.
Mechanism of Action
- High affinity for ergosterol in fungal cell membranes disrupts membrane permeability, causing leakage of cellular contents.
- Underdosage results in fungistatic effects; higher concentrations can become fungicidal.
Antimicrobial Spectrum
- Broad-spectrum antifungal activity against several systemic fungi, including:
- Candida
- Histoplasma
- Cryptococcus
- Blastomyces
- Coccidioides
- Aspergillus
- Sporothrix
- Shows sensitivity in some algae and protozoa (e.g., Leishmania, Trypanosoma).
Limitations and Toxicity
- Not effective against certain clinical pathogens (specifics not provided).
- Renal toxicity arises from two mechanisms:
- Intense renal vasoconstriction.
- Binding to membrane cholesterol in renal tubular cells.
-
Other adverse effects include:
- Anorexia
- Nausea and vomiting
- Anemia
- Cardiac arrhythmias
- CNS signs (notably when given intrathecally)
- Hepatic dysfunction
- Thrombophlebitis at injection site.
- Cats exhibit increased sensitivity to renal toxicity.
Monitoring and Administration
- Monitoring of renal function is essential, particularly via urine analysis of electrolytes and creatinine.
- Diluted in 5% dextrose for administration.
- Particularly effective in dogs and other species for serious systemic infections.
Alternative Treatments
-
Nystatin: Used for localized infections in skin, mouth, or intestines.
- Dosage for dogs ranges from 50,000-150,000 Units, administered orally three times daily.
- Cats require 100,000 Units, administered orally four times daily.
-
Natamycin: Treats fungal infections, notably fungal keratitis in ocular infections, effective against:
- Candida
- Aspergillus
- Cephalosporium
- Fusarium
- Penicillium.
Studying That Suits You
Use AI to generate personalized quizzes and flashcards to suit your learning preferences.
Description
This quiz covers the class of polyene antibiotics, specifically focusing on Amphotericin B, obtained from Streptomyces nodosus. It includes information on their mechanism of action, solubility, and clinical use.
