[3S] Antimycobacterials Flashcards
1ST LINE DRUGS PKINETICS
● Orally absorbed
● NO BBB Penetration
Isoniazid
1ST LINE DRUGS PKINETICS
Isoniazid acetylation & excretion
● Acetylated by the liver
● Renally excreted
1ST LINE DRUGS ROA
Isoniazid
PO/IV
1ST LINE DRUGS MOA
● Bactericidal
● Inhibits mycolic acid synthesis
● Activated by KatG
● Forms a covalent complex with AcpM and KasA
● Drug interactions:
o Phenytoin,Mcarbamazepine, benzodiazepines
Isoniazid
1ST LINE DRUGS RESISTANCE MECHANISM
- Overexpression of inhA gene
- Mutation or deletion of katG gene
- Promotermutationsresulting in overexpression of ahpC
- Mutations in kasA
Isoniazid
1ST LINE DRUGS CLINICAL APPLICATIONS
● Single most important drug for TB
o PTB (Combination Therapy)
● Sole - LTBI, Close contact, prophylaxis
Isoniazid
1ST LINE DRUGS TOXICITIES
● Peripheral neuritis
● Restlessness, Muscle twitches, Insomnia
● CNS toxicity: Memory loss, Psychosis, Ataxia Seizures
Isoniazid
1ST LINE DRUGS TOXICITIES
● Hemolysis (G6PD)
● CYP 450 inhibitor (↑ conc)
● Fever and skin rashes
Isoniazid
1ST LINE DRUGS TOXICITIES
Isoniazid most common toxicity
Hepatitis
1ST LINE DRUGS TOXICITIES
● Drug-induced lupus erythematosus
● Peripheral neuropathy
● Miscellaneous: Hematologic abnormalities, Pyridoxine deficiency anemia, Tinnitus, GI discomfort
Isoniazid
1ST LINE DRUGS PKINETICS
● Distributed to most tissues including CNS
● Enterohepatic cycling
o Liver into bile
● High protein binding
Rifampin/Rifampicin
1ST LINE DRUGS PKINETICS
Rifampin excretion
Feces, urine
1ST LINE DRUGS ROA
Rifampin
PO/IV
1ST LINE DRUGS MOA
● Bactericidal
● Inhibits DNA-dependent RNA polymerase
● Binds to beta-subunit of bacterial DNA-dependent
RNA polymerase
● Inhibits RNA synthesis
● Drug interactions:
o Methadone, Anticoagulants, Cyclosporine
Rifampin
1ST LINE DRUGS RM
- Any one of several possible point mutations in rpoB
- These mutations result in reduced binding of rifampin to NA polymerase
Rifampin
1ST LINE DRUGS CLINICAL APPLICATIONS
● PTB (combination therapy)
● (Sole) INH-resistant TB or INH-intolerant LTBI
● Atypical mycobacterial infections
Rifampin
1ST LINE DRUGS CLINICAL APPLICATIONS
● Leprosy - delays resistance to dapsone
● MRSA, PRSP
● Meningococcal & Staphylococcal carriage
● Prophylaxis against H. influenzae type b disease
Rifampin
1ST LINE DRUGS TOXICITIES
Orange color
Rifampin
1ST LINE DRUGS TOXICITIES
● Skin rashes, Thrombocytopenia, Nephritis
● Cholestatic jaundice, Light- chain proteinuria, Flu-like syndrome
● Acute tubular necrosis (associated)
Rifampin
1ST LINE DRUGS PKINETICS
● Orally absorbed
● Distributed to most tissues including CNS
Ethambutol & Pyrazinamide
1ST LINE DRUGS PKINETICS
Ethambutol excretion
Urine
1ST LINE DRUGS ROA
Ethambutol
PO
1ST LINE DRUGS MOA
● Bactericidal or Bacteriostatic depending on the bacteria’s reproductive activity
● Inhibits arabinosyltransferase enzyme needed for cell wall synthesis (polymerization of arabinoglycan)
● Encoded by embCAB operon
Ethambutol
1ST LINE DRUGS RM
- Mutation in embB gene if drug is used alone.
- Results in overexpression of emb gene products or within the embB strucutral gene.
Ethambutol
1ST LINE DRUGS CLINICAL APPLICATIONS
● TB (combination therapy); usually EMB + INH, RIF, or PZA
● Combination with other agents for nontuberculous mycobacterial infections (MAC and M. kansasii)
Ethambutol
1ST LINE DRUGS TOXICITIES
● Dose-dependent visual disturbances
● Headache, confusion, hyperuricemia
Ethambutol
1ST LINE DRUGS TOXICITIES
● Eyes : Retrobulbar neuritis, loss of visual acuity, red-green color- blindness
Ethambutol
1ST LINE DRUGS PKINETICS
Pyrazinamide metabolism
Metabolized by the liver
Partly to pyrazinoic acid
1ST LINE DRUGS ROA
Pyrazinamide
PO
1ST LINE DRUGS MOA
● Bacteriostatic
● Inhibits tubercle bacilli
● Converted to pyrazinoic acid
● Encoded by pncA
● Disrupts mycobacterial cell membrane metabolism and transport functions
Pyrazinamide
1ST LINE DRUGS RM
- Impaired uptake of pyrazinamide
- Mutations in pncA that impair conversion of PZA to its active form
- Drug-efflux systems, especially when used alone
Pyrazinamide
1ST LINE DRUGS CLINICAL APPLICATIONS
● MTB (combination therapy)
● Sterilizing agent with INH or RIF that deals with intracellular mycobacteria
Pyrazinamide
1ST LINE DRUGS TOXICITIES
● Joint pains, myalgia, GI irritation, rash
● Nausea, vomiting, fever, photosensitivity
● Hepatotoxicity
Pyrazinamide
1ST LINE DRUGS TOXICITIES
● Hyperuricemia (gout)
● Contraindicated in pregnant women
Pyrazinamide
2ND LINE DRUGS PKINETICS
Can cross the BBB
Streptomycin
2ND LINE DRUGS PKINETICS
Streptomycin excretion
Renal
2ND LINE DRUGS ROA
Streptomycin
IV
2ND LINE DRUGS MOA
● Mainly affects extracellular tubercle bacilli
● Irreversible inhibition of protein synthesis via the binding to the 30S subunit
Streptomycin
2ND LINE DRUGS CLINICAL APPLICATIONS
● Life-threatening TB disease (meningitis, miliary dissemination, severe organ TB)
● Pott’s disease, extracellular TB
Streptomycin
2ND LINE DRUGS TOXICITIES
● Ototoxicity & nephrotoxicity
● Vertigo and hearing loss
Streptomycin & Rifabutin
2ND LINE DRUGS PKINETICS
Ethionamide metabolism
Liver
2ND LINE DRUGS ROA
Ethionamide
PO
2ND LINE DRUGS MOA
● INH derivative; also inhibits mycolic acids.
● Low-level cross resistance between isoniazid and ethionamide
Ethionamide
2ND LINE DRUGS CLINICAL APPLICATIONS
● PTB treatment regimen for INH-intolerant patients
● Can be used for leprosy treatment
Ethionamide
2ND LINE DRUGS TOXICITIES
Hepatotoxicity, GI irritation, and neurotoxicity
Ethionamide
2ND LINE DRUGS PKINETICS
Capreomycin excretion
Urin
2ND LINE DRUGS ROA
Capreomycin
PO/IV
2ND LINE DRUGS MOA
● Binds to 70S ribosomal subunit.
● Cross-resistance with amikacin and kanamycin
● Resistance occurs due to rrs, eis, tlyA gene mutations
Capreomycin
2ND LINE DRUGS CLINICAL APPLICATIONS
Treatment of drug- resistant tuberculosis
Capreomycin
2ND LINE DRUGS TOXICITIES
● [Ototoxicity] tinnitus, deafness, vestibular disturbances
● Nephrotoxicity
Capreomycin
2ND LINE DRUGS PKINETICS
Cycloserine excretion & ROA
Renal & PO
2ND LINE DRUGS MOA
Inhibits cell-wall synthesis (peptidoglycans)
Cycloserine
2ND LINE DRUGS CLINICAL APPLICATIONS
Used in combination treatment for Mycobacterium avium complex and TB
Cycloserine
2ND LINE DRUGS TOXICITIES
● Peripheral neuropathy,
● CNS dysfunction (depression and psychoses)
Cycloserine
2ND LINE DRUGS PKINETICS
Aminosalicylic Acid excretion & ROA
Renal & PO
2ND LINE DRUGS MOA
Inhibits folic acid synthesis and mycobactin synthesis
Aminosalicylic Acid
2ND LINE DRUGS CLINICAL APPLICATIONS
Anti-mycobacterial agent used in combination to treat active tuberculosis
Aminosalicylic Acid
2ND LINE DRUGS TOXICITIES
● High concentrations can cause crystalluria
● Gastrointestinal symptoms, hypersensitivity, hemorrhage
● Hepato-, nephro-, and thyroid toxicities
Aminosalicylic Acid
2ND LINE DRUGS PKINETICS
Kanamycin & Amikacin excretion & ROA
Renal & IV/IM
2ND LINE DRUGS MOA
● No cross-resistance with streptomycin and amikacin
● Binds to 30S subunit
● Interferes with mRNA binding and tRNA acceptor
sites
o to cause misreading of t-RNA
o disrupting protein synthesis
Kanamycin & Amikacin
2ND LINE DRUGS CLINICAL APPLICATIONS
Used in combination for Treatment of streptomycin- resistant or MDR-TB
Kanamycin & Amikacin
2ND LINE DRUGS TOXICITIES
● Ototoxicity
● Nephrotoxicity
Kanamycin & Amikacin
2ND LINE DRUGS PKINETICS
Fluoroquinones excretion & ROA
● Renal excretion
● Partial biliary excretion
● PO/IV
2ND LINE DRUGS MOA
● Class-resistance (resistance to one fluoroquinolone indicates resistance to others)
● Inhibits DNA gyrase and topoisomerase IV to block bacterial DNA synthesis, inhibiting cell division
Fluoroquinones
2ND LINE DRUGS CLINICAL APPLICATION
MTB resistant to first-line agents
Fluoroquinones
2ND LINE DRUGS TOXICITIES
● Nausea, vomiting, diarrhea, abnormal liver function, headache, dizziness.
● Peripheral neuropathy and central neurotoxicities (agitation, impaired memory etc.)
Fluoroquinones
2ND LINE DRUGS PKINETICS
Linezolid excretion & ROA
Renal & PO
2ND LINE DRUGS MOA
● Point mutations causes linezolid resistance
● Inhibitor of monoamine oxidase enzymes and binds to the 50S subunit to prevent bacterial division
Linezolid
2ND LINE DRUGS CLINICAL APPLICATIONS
Used in combination with pyroxidone for treatment of MDR tuberculosis
Linezolid
2ND LINE DRUGS TOXICITIES
● Bone marrow suspension, irreversible peripheral and optic neuropathy
● Serotonin syndrome
Linezolid
2ND LINE DRUGS PKINETICS
● 20% bioavailability
● 53% of oral dose
Rifabutin
2ND LINE DRUGS PKINETICS
Rifabutin excretion, metabolism, ROA
Excreted in urine & feces
Hepatic metabolism
PO
2ND LINE DRUGS MOA
● Inhibition of DNA- dependent polymerase RNA
● Cross-resistance with rifampin
Rifabutin
2ND LINE DRUGS CLINICAL APPLICATIONS
● Equally effective as anti- mycobacterial agent
● For HIV/AIDS patients taking ARVs
● MAC, MTB, M. fortuitum
Rifabutin
2ND LINE DRUGS PKINETICS
Rifapentine excretion & ROA
Renal & fecal + PO
2ND LINE DRUGS MOA
● Same drug interaction profile as Rifampin (Inhibiting of DNA-dependent RNA polymerase)
Rifapentine
2ND LINE DRUGS CLINICAL APPLICATIONS
● Active against Mycobacterium avium complex and M tuberculosis
● Used in combination with isoniazid to LTBI in PLHIVs
Rifapentine
2ND LINE DRUGS TOXICITIES
● Should NOT be used to treat ACTIVE tuberculosis in HIV patients due to risk of relapse
● Can cause subtherapeutic levels of ARVs
Rifabutin
2ND LINE DRUGS PKINETICS
Not absorbed from the GI tract
Rifaximin
2ND LINE DRUGS ROA
Rifaximin
PO
2ND LINE DRUGS CLINICAL APPLICATIONS
Traveler’s diarrhea
Rifaximin
2ND LINE DRUGS TOXICITIES
Nausea, headache, dizziness, joint pain, muscle tightening
Rifaximin
2ND LINE DRUGS PKINETICS
Bedaquiline excretion & ROA
Feces & PO
2ND LINE DRUGS MOA
Inhibits a bacteria’s generation of energy by interfering with their proton pump of mycobacterial ATP
Bedaquiline
2ND LINE DRUGS CA
Treats isoniazid and rifampin tuberculosis
Bedaquiline
2ND LINE DRUGS TOXICITIES
Nausea, arthralgia, headache, hepatotoxicity, cardiac toxicity
Bedaquiline
DRUGS FOR LEPROSY PKINETICS
Penetrates tissues well
Dapsone
DRUGS FOR LEPROSY PKINETICS
Dapsone elimination & ROA
Urine & PO
DRUGS FOR LEPROSY MOA
● Mainly affects extracellular tubercle bacilli
● Irreversible inhibition of protein synthesis via the binding to the 30S subunit
Dapsone (same w/ Strep)
DRUGS FOR LEPROSY CA
Most active drug for M. leprae
Dapsone
DRUGS FOR LEPROSY TOXICITIES
GI irritation, fever, skin rashes, methemoglobinemia, hemolysis in patients with G6PD
Dapsone & Sulfones (Acedeapsone)
DRUGS FOR LEPROSY TOXICITIES
Requires folic acid supplements
Dapsone & Sulfones (Acedeapsone)
DRUGS FOR LEPROSY PKINETICS
● Acetylated dapsone
● Distributed in all tissues
Sulfones
DRUGS FOR LEPROSY PKINETICS
Sulfones excretion & ROA
Renal & IM
DRUGS FOR LEPROSY CA
● Alternative drug for P. carinii pneumonia in HIV patients;
● Possible antimalarial activity
Sulfones
DRUGS FOR LEPROSY PKINETICS
Stored widely in reticuloendothelial tissue and skin
Clofazimine
DRUGS FOR LEPROSY ROA
Clofazimine
PO
DRUGS FOR LEPROSY MOA
Not clearly established
Clofazimine
DRUGS FOR LEPROSY CA
Phenazine dye for multibacillary leprosy
Clofazimine
DRUGS FOR LEPROSY TOXICITIES
Discoloration of the skin and conjunctivae
Clofazimine
DRUGS FOR LEPROSY CA
● 600 mg daily as a sole agent or 600 mg per month in combination therapy for leprosy
● Given with other drugs to prevent resistance
Rifampin
Erythema nodosum leprosum may be suppressed by ______
thalidomide