Antimycobacterials and Antifungals Flashcards
Antimycobacterials work by targeting what in Mycobacteria?
Enzymes used to build the cell wall
Why are antimycobacterials usually given in combination treatments?
Target different enzymes
Minimize bacterial resistance
Mycobacteria replicate slower than “typical” bacteria. What effect does this have?
Easier to control
Harder to treat
What is unique about mycobacteria that makes them resistant to nearly all antibiotics?
They can exist in a dormant state
What is found in the cell walls of mycobacteria that make them structurally different from Gram (+) and (-) bacteria?
Mycolic Acids
(resist penetration)
What is the four drug cocktail used to treat Mycobacterium tuberculosis when it is an active disease?
Rifampin
Isoniazid
Pyrazinamide
Ethambutol
Isoniazid is bactericidal or bacteriostatic?
Bactericidal
What is the mechanism of action of Isoniazid?
Mycolic Acid synthesis inhibitor
Isoniazid is effective against active or dormant (latent) TB?
Both
What are the two most important drugs for Tuberculosis?
Isoniazid
Rifampin
Isoniazid acts as weak Monoamine Oxidase Inhibitor (MAO-I), what drugs may cause an interaction because of this?
Selective Serotonin Reuptake Inhibitor (SSRI)
Serotonin & Norepinephrine Reuptake Inhibitor (SNRI)
What is typically given to all patients who are taking Isoniazid?
Pyridoxine (Vitamin B6)
What are the adverse drug reactions of Isoniazid?
Peripheral Neuropathy (use pyridoxine)
Hepatotoxicity
Hemolysis with G6PD deficiency
Name two common Rifamycins.
Rifampin
Rifabutin
Are Rifamycins bactericidal or bacteriostatic?
Bactericidal
What is the mechanism of action of Rifamycins?
Inhibit DNA-dependent RNA polymerase
Why should you always screen for drug interactions with Rifamycins?
Extremely potent CYP450 inducers
Rifamycins also cause what kind of effect on oral contraceptives?
Reduced effectiveness
(use back up)
Which Rifamycin is the drug of choice for TB?
Rifampin
Which Rifamycin is the drug of choice for mycobacterium avium complex?
Rifabutin
What is a benign adverse drug reaction of Rifamycins that may scare the shit out of your patient?
Orange-red colored secretions
Is Pyrazinamide bacteriostatic or bactericidal?
Bacteriostatic
Why is Pyrazinamide used in the TB cocktail?
Shorten duration of treatment
9 months to 6 months
How long is Pyrazinamide used for?
2 months
What type of patient should not use Pyrazinamide?
Pregnant
What is a common adverse drug reaction caused by Pyrazinamide?
Polyarthralgia (40%)
Is Ethambutol a bactericidal or bacteriostatic?
Bacteriostatic
What is the mechanism of action of Ethambutol?
Inhibits formation of arabinoglycan
(component of cell wall)
When is Ethambutol used?
First 2 months of TB treatment
Who is Ethambutol not recommended for?
Children under 5
What is an adverse drug reaction that may occur when using Ethambutol and is dose-dependent?
Visual Disturbances (reversible)
- patients can’t tell red from green
Name two Polyenes (antifungals).
Amphotericin B
Nystatin
What is the mechanism of action of Polyenes?
Ergosterol binding in fungal cell membranes
(forms leaky pores)
List three adverse drug reactions caused by Polyenes.
Nephrotoxicity
Infusion Reactions
Electrolyte Abnormalities (hypokalemia)
Polyenes have a moderate clinical activity against what?
Zygomycetes
Polyenes are the drug of choice for what infection?
Cryptococcal Meningitis
Name four popular Azoles.
Fluconazole
Itraconazole
Voriconazole
Ketoconazole
What is the mechanism of action of Azoles?
Fungal CYP-450 dependent enzyme inhibitor
(blocks ergosterol synthesis)
What antifungals are considered the “mainstay” of antifungal fungal therapy?
Azoles
What are two adverse drug reactions caused by Azole antifungals?
Hepatotoxicity
QT prolongation
Why do Azoles have a high amount of drug interactions?
CYP450 Inhibitors
How is Fluconazole eliminated from the body and how is this beneficial for treatments?
Renal Elimination
- only Azole with utility for Candiduria
Fluconazole is the drug of choice for what type of fungal infections?
Candidiasis
- except for Candida krusei
Azole medication that is only available in oral formulations.
Itraconazole
Itraconazoles absorption is decreased by decreased gastric acidity caused by things such as PPI, H2 antihistamines. What can you instruct a patient to do in order to help increase the absorption?
Drink Soda
Itraconazole is the drug of choice for what two infections?
Histoplasmosis
Blastomycosis
Voriconazole is more than 90% orally bioavailable, however food decreases its absorption. What should you recommend your patients do?
Administer 1 hour before or after a meal
Voriconazole is the drug of choice for what type of infection?
Invasive Aspergillosis
Posaconazole is an antifungal that is available in either oral suspension, tablet or IV. What should the PO forms be taken with?
Food or Soda
What is an important thing to remember about the suspension and tab form of Posaconazole?
Suspension and Tablet have different dosing
Posaconazole is the drug of choice for what infections?
Prophylaxis of Invasive Aspergillosis and Candidiasis
Name an Echinocandin.
Micafungin (IV)
What is the mechanism of action of Micafungin?
Glucan Synthase Inhibitor
(decreases fungal cell wall synthesis)
What is unique about the adverse drug reactions of Echinocandins?
Excellent Safety Profile
What are possible drug interactions with Echinocandins?
Capsofungin and Micafungin interact with organ transplant rejection drugs.
Echinocandins are the drug of choice for what type of infection?
Invasive Candidiasis
What anti-fungal works by inhibiting epoxidation of squalene
Terbinafine
