Exam 4 - Antifungal Agents & Laxatives Flashcards
Groups of infections that anti-fungal agents treat
Drugs for systemic mycoses (infections)
Drugs for superficial mycoses (infections)
(A few drugs are used for both)
Groups of systemic mycoses
Opportunistic
Nonopportunistic
What are opportunistic systemic mycoses?
Infect an immunocompromised host
Ex: cancer pts, pts in the hospital for a long time
What are nonopportunistic systemic mycoses?
Can occur in any host
Types of organisms that are opportunistic mycoses
Candidiasis
Aspergillosis
Cryptococcosis
Mycomycosis
Types of organisms that cause nonopportunistic mycoses
Sporotrichosis (rose gardner’s disease)
Blastomycosis (decaying wood)
Histoplasmosis (from birds and bats)
Coccidioidomycosis
Classes of antifungal drugs
Polyene antibiotics
Azoles
Echinocandins
Pyrimidine analogs
What is Amphotericin B?
Broad-spectrum antifungal agent (also used against some Protozoa)
Administration of Amphotericin B
Must be given IV (no oral admin)
**Highly toxic. Needs to be infused over 2-4 hours
Uses of Amphotericin B
for most systemic fungal infections
(Esp in immunocompromised patients)
Action of Amphotericin B
Binds to ergosterol (much more than cholesterol) in fungal cell membrane (Bacterial cell membranes lack sterols)
Increases permeability
Cell leaks intercellular cations (esp potassium)
Can be fungistatic or fungicidal
Adverse effects of Amphotericin B
*Infusion reactions
*Nephrotoxicity (need to watch levels)
Hypokalemia
Bone marrow suppression
*Symptoms of Amphotericin B infusion reaction
Fever
Chills
Rigors
Nausea
Headache
What causes infusion reactions with Amphotericin B?
Release of proinflammatory cytokines
(Less intense with lipid-based Amphotericin B formulations)
When do symptoms of Amphotericin B infusion reactions occur?
Begin 1-3 hours after start of infusion and last for about an hour
What is the extent of *nephrotoxicity with Amphotericin B related to?
Related to total dose administered over the full course of treatment
If the dose is >4, residual impairment is likely
How to minimize kidney damage when administering Amphotericin B
By infusing 1 L of saline on days of treatment
*Avoid concurrent use of other nephrotoxic drugs (Aminoglycosides, cyclosporines)
NSAIDs should be avoided
Monitor serum creatinine every 3-4 days
And reduce dosage if >3.5mg/dL
How to prevent hypokalemia when administering Amphotericin B
*Monitor serum levels
(Results from damage to the kidneys)
Potassium supplements may be needed
Hematologic effects caused by Amphotericin B
Can cause bone marrow suppression
Anemia (must monitor hematocrit)
What are Azoles?
Broad spectrum antifungal drugs
Good alternative to ampho B for most systemic mycoses (have lower toxicity)
Administration of Azoles
Can be given orally
Disadvantage of Azoles
Inhibit P450 drug-metabolizing enzymes and can increase the levels of many other drugs
Prototype Azole
Itraconazole (Sporanox)
Uses of Itraconazole
Systemic mycoses (alternative to ampho B)
Side effects of Itraconazole (Sporanox)
*Cardiosuppression (transient decrease in ventricular ejection fraction)
Liver damage
GI effects (nausea, vomiting, diarrhea)
Can inhibit drug-metabolizing enzymes
If a patient is taking Itraconazole (Sporanox) lab work needs to be monitored if they are taking which other drugs?
Digoxin
Coumadin
Cyclosporin
Two groups of superficial mycoses
Caused by two groups of organisms:
- Candida species
- Dermatophytic infections
Where are Candida species found? And where do they usually cause infections?
Usually in mucous membranes and moist skin
Chronic infections may involve scalp, skin, and nails
Where do dermatophytic infections usually occur?
Usually confined to skin, hair, and nails
(More common than candida infections in nails)
In general, how are Azoles administered, what are Azoles used for, and what are their suffixes?
Topical or PO
Used for superficial mycoses
-azole
Suffix for allylamines
-afine
In general, what are polyene antibiotics used for and what is the suffix?
Candida infections of the skin, mouth, and vagina
-statin
Mechanism of action for Azoles
Inhibits the synthesis of ergosterol (essential component of the cytoplasmic membrane)
This causes increased membrane permeability and leakage of cellular components
Administration of Fluconazole (Diflucan)
Oral
IV
(Dosage is the same for both)
Adverse effects of Fluconazole (Diflucan)
N&V
Headache
Abdominal pain
Diarrhea
What is another alternative to ampho B for systemic mycoses
Ketoconazole (Nizoral)
Uses of Ketoconazole (Nizoral)
Alternative to ampho B for systemic mycoses
Less toxic, less effective, slower effects
More useful in suppressing chronic infections than in treating severe, acute infections
Examples of superficial mycoses
Oral candidiasis (thrush)
Vulvovaginal candidiasis
Risk factors for superficial mycoses
Pregnancy
Diabetes
Debilitation
HIV
Oral contraceptives
Systemic glucocorticoids
Anticancer agents
Systemic antibiotics
Fungal infection of the nails
Onychomycosis
Treatment for onychomycosis
Oral therapy
- Lamisil and Itraconazole (Sporanox)
Topical therapy
- Ciclopirox (Penlac Nail Lacquer)
What is Nystatin (Mycostatin)?
Polyene antibiotic
What is Nystatin used for?
Only for candidiasis
Drug of choice for intestinal candidiasis
Also used for Candida infections in skin, mouth, esophagus, and vagina
Administration of Nystatin
Orally
Topically
Contraindications of laxative use
Pts with abdominal pain, nausea, cramps, or other symptoms of appendicitis, regional enteritis, diverticulitis, and ulcerative colitis
Acute surgical abdomen
Fecal impaction or bowel obstruction
Habitual use
Use with caution in pregnancy and lactation
Types of laxatives
Bulk-forming
Surfactant
Stimulant
Osmotic
Types of bulk-forming laxatives
Methylcellulose (Citrucel)
Psyllium (Metamucil)
Function of bulk forming laxatives
Function similarly to dietary fiber: swell with water to form a gel to soften and increase fecal mass
Uses of bulk forming laxatives
Preferred treatment for temporary treatment of constipation
Administration of bulk forming laxatives
Mix in full glass of water
May take 1-3 days to work
Adverse effects of bulk forming laxatives
Esophageal obstruction
Prototype surfactant laxative
Docusate sodium (Colace)
Effects of surfactant laxatives on bowel
Stimulate intestinal motility
Increase quantities of water and electrolytes in the intestinal lumen
Use of surfactant laxatives
Opioid-induced constipation
Types of stimulant laxatives
Bisacodyl (Correctol, Dulcolax)
Castor oil
Senna (Senokot, Ex-Lax)
Administration of Bisacodyl (Correctol, Dulcolax)
Tablets
Suppositories
Administration of castor oil
Sometimes given before surgical procedures
Sometimes mixed and given as enema
Works in 2-6 hours
How to stimulant laxatives work? And how long do they take to work?
Stimulate intestinal motility
Results in 6-12 hours
What are stimulant laxatives used for?
Opioid induced constipation
Types of osmotic laxatives
Laxative salts:
Magnesium hydroxide
Sodium phosphate
Magnesium citrate
Magnesium sulfate
How do laxative salts work?
Poorly absorbed salts that draw water into the intestinal lumen
The fecal mass softens and swells, wall stretches, and peristalsis is stimulated
How long does it take for results of osmotic laxatives?
Low doses: 6-12 hours
High doses: 2-6 hours
Type of laxative used for chronic constipation
Polyethylene glycol (PEG)
(Miralax, Glycolax, Peglax)
What type of laxative is polyethylene glycol?
Osmotic laxative
Most abused type of laxatives
Osmotic laxatives
What are high doses of osmotic laxatives used for?
Diagnostics (colonoscopies)
Surgery
Ingested poisons
Anti-helmintic
Adverse effects of osmotic laxatives
Dehydration: substantial water loss
Renal decline: toxicity
Sodium retention: exacerbated heart failure, HTN, edema
Which types of laxatives should not be given to patients with kidney issues
Osmotic laxatives
Laxatives with salt because they can build up in kidneys
3 types of bowel-cleansing products for colonoscopies
Sodium phosphate
Polyethylene glycol
Combination - sodium picosulfate, magnesium oxide
What causes laxative abuse?
Misconception that bowel movements must occur daily
Consequences of laxative abuse
Diminished defecatory reflexes, leading to further reliance on laxatives
Electrolyte imbalance
Dehydration
Colitis
