click below
click below
Normal Size Small Size show me how
RS Pharmacology
Respiratory System Pharmacology- Anti- TB
Question | Answer |
---|---|
First line anti-tuberculous agents: | Isoniazid (INH) Rifampin “Rifadin” or “Rimactane” Ethambutal Streptomycin Pyrazinamide Island Rivers Establish Shoddy Palms |
Secondary or Second Line Drugs used as anti-tuberculous agents: | Ethionamide Capreomycin Cycloserine Para-Amino-Salicylic Acid (PAS) Amikacin Flouroquinolones Linezolid Rifabutin Rifapentine Earthworms Create Creepy Pumpkins And Ferrets List Robotic Robots |
Most active anti-TB drug: | Isoniazid |
General characteristics of Isonazid: | Small molecule, water soluble, Structurally related to Pyridoxine Prodrug, activated by KatG, the mycobacterial catalase peroxidase |
MOA of Isonazid: | Blocks mycolic acid synthesis-consequently mycobacterial cell wall synthesis- bactericidal effect in growing TB cells Widely distributed, penetrates into macrophages Metabolized by acetylation |
Resistance of Tb to Isonazid: | 1 in 10^6 when used alone 1 in 10^12 when used in combination |
Side effects of Isonazid use: | Hepatitis-1% Anorexia N,V Jaundice Neuropathy:10-20% Neurotoxicity: Memory loss, Psychosis,Seizures Tinnitus GIT effects Interactions |
Neuropathy is more likely to occur in: | Slow acetylators Malnutrition AIDS Alcoholics DM Uremia Due to pyridoxine deficiency |
Rifampin was isolated from: | Stretomyces miditerranei |
Rifampin is effective in cases of: | Gram+ve and –ve bacteria Mycobacteria Enterococci Chlamydia |
MOA of rifampin: | Binds to the beta subunit of bacterial DNA-dependant RNA polymerase and therefore inhibits RNA synthesis Bactericidal Widely distributed Hepatic metabolism - enterohepatic recirculation |
What are the clinical uses of Rifampin? | TB Leprosy Meningococcal Carrier State Prophylaxis in H.influenzae. Staph osteomyelitis and valve endocarditis. |
In Jordan it is available only in | MOH Ministry of Health |
Rifampin toxicity can cause: | Orange color to secretions( tears, urine, sweat). Nephritis Rashes Hepatitis Flu-like syndrome Liver Enzyme Inducer- lower serum levels of many drugs |
Uses of streptomycin: | Anti-tuberculus agent. Plague Tuleremia Brucellosis Endocarditis |
Streptomycin toxicity causes: | Allergy: Fever, Rashes Pain, after i.m injection Vestibular toxicity---- Irreversible Nephrotoxicity |
What are the Indications for Secondary or Second- Line Drugs? | 1) Resistance to first –line drugs 2) Failure of clinical response to conventional therapy 3) Occurrence of serious treatment-limiting adverse drug reactions 4) When expert guidance is available to deal with the toxic effects |
MOA of Ethionamide: | Related to Isoniazid Blocks mycolic acid synthesis |
How is Ethionamide administered? | Orally |
Disadvantages of taking Ethionamide: | Poorly tolerated: Severe GIT irritation Neurotoxic Hepatotoxic |
MOA of Capreomycin: | Peptide protein synthesis inhibitor |
Administration of Capreomycin via: | Injection |
Disadvantages of taking Capreomycin: | Nephrotoxic, ototoxic Local pain and sterile abscesses may occur |
MOA of Cycloserine: | Inhibits cell wall synthesis |
Disadvantages of taking Cycloserine: | Peripheral neuropathy CNS toxicity including depression and psychotic reactions |
MOA of Para-Amino-Salicylic Acid (PAS): | Folate synthesis antagonist |
Dosage of PAS: | 8-12 gm/day |
Advantages of taking PAS: | Well absorbed Widely distributed, except CNS Excreted in urine |
Disadvantages of taking PAS: | GI toxicity Hypersensitivity reactions Crystalluria |
Uses of Amikacin: | Multidrug-resistant strains Atypical mycobacteria |
Use of Florquinone: | Combination, because resistance develops rapidly when used alone |
When is Linezolid used? | For multi-drug resistant strains \LAST resort |
Side effects of Linezolid use: | Bone marrow suppression Irreversible peripheral and optic neuropathy |
MOA of Rifabutin and Rifapentine | Related to Rifampin. Inhibit bacterial RNA polymerase. Both, like Rifampin, are inducers for CYP P450 enzymes. But Rifabutin is a less potent inducer |
Rifabutin is indicated in place of Rifampin in | the treatment of TB in HIV-infected patients receiving protease inhibitor or nonnucleoside reverse transcriptase inhibitor |
Drugs used in the cases of Atypical Mycobacteria | M.tuberculosis complex: Erythromycin Sulphonamides Tetracycline M.avium complex: Important and common cause of disseminated TB in late stages of AIDS Azithromycin or Clarithromycin Ethambutal & Ciprofloxacin |
Stats for TB: | Annually, 9 million cases recorded 5% of these are drug-resistant tuberculosis Forty-nine percent of those with XDR-TB died compared to 19 percent of patients with ordinary MDR-TB |