Anti Mycobacterial Flashcards
What is used for prophylaxis to M. Tuberculosis
Isoniazid
What are the drugs used in the treatment of M. Tuberculosis
RIPE- Rifampin, Isoniazid, pyrazinamide and ethambutol
Which drug is used to treat M. Leprae tuberculoid form
Dapsone and Rifampin
Which drug is used to treat M. Leprae lepromatous form
Add clofazimine to phenazine
What can phenazine do to the skin over time
Cause skin discolouration pink -> brown/black
What is the mechanism of action of Rifamycins
Inhibit DNA dependant RNA polymerases
Drugs of rifamycin group
Rifampin
Rid abit in
What are Rifamycins used to treat
Used in M. Tuberculosis (Rifampin is first line) and meningococcal prophylaxis
Rifamycins use in children
Prophylaxis in contacts of children with H influenza type B
Rifamycins adverse effects
Orange blood fluids, CYP 450 inducer (drug interactions) and hepatotoxicity
Which of the Rifamycins is favoured with HIV and why
Rifabutin is favoured over Rifampin in HIV infection due to less p450 activation and hepatotoxicity
4Rs of rifampin
- RNA polymerase inhibitors
- ramps up p450
- rapid resistance of used alone
- red orange body fluids
What is the mechanism of action of Isoniazid (INH)
Decreases the synthesis of mycolic acid
Isoniazid is a pro drug what enzyme is needed to get it to its active form
KatG
When is Isoniazid used with TB infections
- It is the only drug used as solo prophylaxis
- it is also used as mono therapy for latent TB
Isoniazid adverse effects
Hepatotoxicity, Vitamin B6 Deficiency leading to peripheral neuropathy
What is administered with isoniazid to prevent B6 deficiency?
Pyridoxine (VitB6)
How does isoniazid affect the p450 system
It inhibits P450 which inhibits the metabolism of phenytoin
How is resistance developed against isoniazid
Underexpression of KATG gene
Mechanism of action of pyrazinamide
Inhibits fatty acid synthesis required for cell membrane function
Pyrazinamide Adverse effects
Hyperuricemia (gout) and hepatotoxicity
Mechanism of action of ethambutol
Inhibits the enzyme ARABINOSYL transferase and cell wall formation
Ethambutol AEs
Optic neuropathy (Red-green colourblindness) EYEthambutol Hyperuricemia
What are the second line drugs of anti mycobacterium
Aminoglycosides
Macrolides
Ethinoamide
Which aminoglycoside is used for mycobacterium
Streptomycin
Mechanism of action of aminoglycosides
Interferes with 30S component of ribosomes
Aminoglycosides AEs
Ototoxicity-vestibular toxicity (vertigo,ataxia,dizziness)
Nephrotoxicity(acute tubular necrosis and glomerular toxicity)
Cochlear (deafness and tinnitus)
Which macrolides are used for mycobacterium
Clarithromycin and azithromycin
Macrolides mechanism of action
Interferes with 50S component of ribosomes
Macrolides AEs
Prolonged QT interval of ECG, diarrhea, cholestatic jaundice and ototoxicity
What is ethionamide
Isoniazid analog
Macrolides contraindications
Allergic reactions and hepatic dysfunction
Ethionamide adverse effect
Can cause hypothyrodism
