Test 3: Wk11: 5 Anti- Tuberculosis Drugs - Allman Flashcards
can pts with latent TB spread TB to others
no
MDR TB
resistant to at least INH and RIF
pts with resistance to Rifampin alone
better prognosis than MDR strains however at increased risk of tx failure/ addition resistance
XDR TB
extensive drug resistance
Resistant to INF and RIF plus FQN and at least one of the three injectable drugs
Life cycle of TB
- Active M tuberculosis
- Macrophage
- Walled off by macrophage
- Leukocytes
- Granuloma
- Active M tuberculosis
Prolonged treatment is required for successful eradication
Typically 6 months for routine Pulmonary TB Tx
TB Pericarditis and Meningitis
Initial adjunctive corticosteroid therapy with dexamethasone should be given for 6 weeks for ptns with TB Meningitis
Initial adjunctive corticosteroid therapy should not be routinely used; reserved for only selected ptns
ART CD4 <50/mm3
Start ART within first 2 weeks of TB treatment
CD4 >50/mm3
Start ART by 8-12 weeks of TB treatment
TB meningitis tx
TB meningitis = Do NOT start before 8 10 weeks of TB treatment
pts w/ HIV and TB have increased risk of
developing paradoxical worsening of sx and clinical manifestations of TB
Immune Reconstitution Inflammatory Syndrome IRIS
in HIV pts rxns develop as a consequence of reconstitution of immune responsiveness brought on by ART
Signs of IRIS may include (7)
High fevers
Worsening respiratory symptoms
Increase in size and inflammation of involved lymph nodes, new lymphadenopathy,
Expanding central nervous system (CNS) lesions,
Worsening of pulmonary parenchymal infiltrations
New or increasing pleural effusions
Development of intra abdominal or retroperitoneal abscesses
Starting ART within 2 weeks after starting tuberculosis therapy have higher
rates of — than those who start between 8 12 weeks
IRIS
does development of IRIS worsen treatment outcomes for either TB or HIV infection
no
IRIS may cause
severe or fatal neurological complications
Intensive Phase of TB tx
2 months (knocking down the volume)
Continuation Phase of TB tx
4 months (de escalate)
Dosing Guidelines
Daily dosing
Twice or Thrice weekly dosing
TB therapy requires
Requires Directly Observed Therapy (DOT)
4 first line agents for TB
isoniazid
Ethambutol
Pyrazinamide
Rifampin
Isoniazid function
inhibits cell wall synthesis
Ethambutol function
inhibits cell wall synthesis
Pyrazinamide function
direct target unclear
disrupts plasma membrane
disrupts energy metabolism
Rifampin function
inhibits RNA synthesis
3 Major Rifamycins
Rifampin
Rifabutin
Rifapentine
Rifampin
Mechanism of Action
inhibits DNA dependent RNA pol - suppression of initiation of chain formation in RNA Synthesis
Rifampin bactericidal function
Bactericidal: kills slow growing mycobacteria present within
macrophages and in caseating granulomas
Rifampin is active against
Active against some gram positive and gram negative bacteria.
(Reserved for TB, except in very rare
Rifampin Combination therapy with
INH
Rifampin Distribution
Widely distributed; excellent tissue distribution
CNS, tuberculosis abscesses, and intracellular sites
Rifampin Metabolism
Primarily metabolized by deacetylation
Autoinduction of metabolism occurs
Maximal induction at ~ 6 doses, whether given daily or twice weekly
Rifampin
Adverse Effects
Transient elevation in serum transaminases
Hepatotoxicity (rare)
GI upset (frequent)
Hypersensitivity (rare)
Discoloration of bodily fluids
what drug causes orange discoloration of sweat tears and urine
Rifampin
Rifampin Hepatotoxicity
Risk factors: alcoholics with preexisting liver disease.
Augmented when combined with INH
Rifampin
Hypersensitivity (rare)
Flushing, fever, pruritus
Systemic flu like syndrome
Thrombocytopenia
Rifampin
Drug Interactions
Proliferation of the smooth endoplasmic reticulum in
hepatocytes
Results in an increase in cytochrome p 450 (CP450) activity.
Rifampin increases metabolism of
P450
Warfarin
Theophylline
Narcotics
Oral Hypoglycemics
Steroids (oral contraceptives)
Rifampin
Place in Therapy
Treatment of active TB
2nd line agent for preventative therapy
Rifamycin derivative.
Rifabutin (Mycobutin)
when is rifabutin used
when pts are receiving meds with unacceptable interactions with Rifampin or had intolerance to rifampin
More active than rifampin against Mycobacterium avium
complex
Rifabutin (Mycobutin)
Rifabutin is used in the tx of
More active than rifampin against Mycobacterium avium
complex (MAC)
Rifabutin ADRs (7)
Rash GI Arthralgias Myalgias Discoloration of urine/sweat/ and tears neutropenia hepatoxicity
Used once weekly with INH in the continuation phase of
SPECIFIED treatment of TB
Rifapentine (Priftin)
Ptn must be HIV negative to use
Rifapentine (Priftin®)
pt must have — to take Rifapentine
Non cavitary , drug susceptible pulmonary tuberculosis who have
negative sputum smears at completion of the initial phase of treatment
advantage of Rifapentine
Once weekly
Rifapentine ADRs
similar to RIfampin
Isoniazid (INH)
Mechanism of Action
Inhibits synthesis of mycolic acid
Important constituent of mycobacterial cell walls
— Actively transported into bacterium
INH
INH kills actively growing organisms in
the extracellular environment
INH inhibits
growth of formant organisms within macrophages preventing granulomas
INH metabolism
Primarily acetylation
INH important metabolite
Monoacetyl hydrazine
Monoacetyl hydrazine excreted
in urine or further acetylated to diacyl form or hydroxylated to electrophile intermediated
— is responsible for hepatotoxic effects with INH
electrophile intermediated
Rates of acetylation of INH & mono acetyl hydrazine dependent on
Dependent on an individual’s phenotypic classification
IMH classifications
slow or rapid acetylator
Slow acetylators of INH may lead to
higher blood concentrations
Caucasians acylation of INH
equally divided fast and slow
Eskimos and Japanese acylation of INH
rapid
Egyptians acylation of INH
slow
INH half life in rapid acetylators
1-2 hrs
INH half life in slow acetylators
2-5 hrs
INH serum transaminase
transient elevation ~15% within first 8-12 wks of therapy
INH hepatotoxicity risk factors
age, liver dz,
4-8 wks of tx use rifampin
INH neurotoxicity
alcoholics, children, malnourished, slow acetylators
prevent neurotoxicity if INH
Pyridoxine (Vitamin B6)
hypersensitivity in INH
rare
Isoniazid
Place in Therapy
Treatment of active TB
Preventative therapy for patients with (+) PPD
INH
Pyrazinamide (PZA)
Mechanism of Action
not well documented
PZA bactericidal toward
dormant organisms residing in the acidic
environment within macrophages
PZA metabolism
Hydrolyzed in liver to active pyrazinoic acid
PZA elimination
5 hydroxypyrazinoic acid ( hydroxylated pyrazinoic acid) is excreted by the kidneys.
PZA t 1/2
9-10hrs
PZA ADEs
Hepatotoxicity
hyperuricemia
GI
Hypersensitivity
hepatotoxicity PZA
more frequent with high dose
baseline hepatic function should be obtained
monitor for hepatitis
PZA hyperuricemia
decreased renal excretion of uric acid
Pyrazinoc acid competes with uric acid for elimination
PZA hypersensitivity
photosensitivity and rash
Ethambutol (ETH, EMB, Myambutol) MOA
not documents
Bacteriostatic
ETH pharmacokinetics
60-80% of parent compound + inactive metabolite excreted in urine
Ethambutol
Adverse Effects
Optic neuritis (Retrobulbar neuritis)
Optic neuritis ( Retrobulbar neuritis)
Decreased visual acuity and red green color blindness.
Optic neuritis ( Retrobulbar neuritis) reversibility
usually reversible , tim dependent with degree of impairment
Drug that causes eye damage
Ethambutol
Streptomycin MOA
aminoglycoside antibiotic
Streptomycin bactericidal through
inhibition of protein synthesis
Streptomycin inactive against
intracellular organisms; limiting activity to suppression
Streptomycin is used as an alternative for
Ethambutol
Streptomycin absorption
poor in GI
administer IM or IV
Streptomycin ADEs
nephrotoxicity
impairment of 8th cranial nerve
pain at injection site/ abscess formation
TB drug combo Rifamate
Rifampin and Isoniazid
TB drug Combo Rifater
Rifampin, Isoniazid, Pyrazinamide
Bedaquiline MOA
inhibits mycobacterial ATP synthetase
Bedaquiline safety concerns
QT prolongation
increased death potential
— used for MDR only
Bedaquiline
6 2nd line agents
- Para-Aminosalicylate
- Ethionamide
- Cycloserine
- Capreomycin
- Kanamycin
- Amikacin
— most widely used as anti-leprosy agent
Clofazimine (Lamprene)
Clofazimine ADRs
GI
Severe life threatening abdominal pain and organ damage
discoloration of skin and eyes
what causes organ damage with Clofazimine
crystal deposition
2 Macrolides
Clarithromycin and Azithromycin
Macrolides effectivity against TB
unlikely
Macrolides should be used in combination with other agents for — tx
MAC - Mycobacterium Avium Complex
BCG Vaccine
attenuated hybridized strain of M bovis
BCG Vaccine against TB
does not appear to be effective
BCG Vaccine should be avoided in
Pregnant and HIV
BCG Vaccine side effects
prolonged ulceration at vaccine site
lymphadenitis and lupus vulgaris
WHO recommendations of BCG Vaccine
High risk TB and HIV+ infants with no sx
TB Regimens
RIPE or RIPS
RIPE
Rifampin
Isoniazid
Pyrazinamide
Ethambutol
RIPS
Rifampin
Isoniazid
Pyrazinamide
Streptomycin
RIPE / RIPS tx
6mos for general TB tx
Osteo/miliary/meningitis regimen
12-24 mos
Concomitant Illnesses (HIV, Hepatitis) Regimen
Treat concomitant disease states
Renal failure TB regimen
Avoid Streptomycin, Kanamycin, and Capreomycin
Children TB regimen
Avoid Ethambutol if proper assessment is not feasible
TB Suspected Treatment Failure
Lack of clinical progression 6 8 weeks into therapy
Add 2 new TB agents when failure suspected
Evaluate for non adherence or drug resistance
Leprosy Causative agent
Mycobacterium leprae (Leprosy)
2 major groups of Leprosy
Lepromatous widespread
Tuberculoid localized
can leprosy be cultured in vitro
no
Lepromatous Leprosy
disseminated , multibacillary , with loss of specific cell mediated immunity
Tuberculoid Leprosy
localized, paucibacillary , with strong cell mediated immunity)
Paucibacillary = having or made up of few
Leprosy transmission requires
prolonged contact and occurs directly through intact
skin, mucous membranes, or penetrating wounds.
Leprosy infection leads to
Lesions
Hypopigmentation
Loss of sensation (anesthesia)
Leprosy dx
Based on acid fast stain and cytologic examination of affected skin and response to the lepromin skin test
Leprosy multidrug therapy (3 drugs)
Dapsone / Rifampin/ Clofazimine
how long does leprosy tx last
3-5 years
Dapsone MOA
competitive inhibitor of folic acid synthesis
Competitive inhibition of dihydropteroate synthase which prevents
bacterial utilization of para aminobenzoic acid
Dapsone is a
bacteriostatic
Dapsone is absorbed
rapidly and completely from the GI tract
Dapsone ADRs
Hypersensitivity reaction
Fever, Malaise, Dermatitis, Jaundice
Dapsone hypersensitivity
sulfone syndrome
Dapsone Sulfone Syndrome sx occur
1-4 wks into therapy
Mycobacterium Avium Complex (MAC) sx
fever, night sweats, wt loss, anemia
MAC stands for
Mycobacterium Avium Complex
MAC usually occurs in
Advanced HIV pts
MAC tx
combination therapy
MAC preferred tx
Clarithromycin
Ethambutol
Rifampin
GI Upset, Drug Drug Interactions, Orange discoloration, Hepatotoxicity
Isoniazid
Neurotoxicity, Peripheral Neuropathy, Hepatotoxicity
PZA
GI Upset, Hyperuricemia , Hepatotoxicity
Ethambutol
Optic Neuritis, Children
Streptomycin
Neurotoxicity (8 th cranial nerve Vertigo ), Nephrotoxicity potential