TB II Flashcards
What are the side effects of Rifampicin?
Nausea, GI disturbances
Discolouration of body fluids
(tears, saliva, urine, faeces) orange/red
Enzyme induction
What pt education will you give the pt regarding taking rifampicin?
Must be taken with food
What is a contraindication of Rifampicin?
Oral contraceptives
What are the side effects of isoniazid?
Peripheral neuropathy (burning / pins & needles in feet & legs)
How can you prevent SE of Isoniazid?
Supplement with pyridoxine
What are the side effects of Ethambutol?
Optic neuritis
Vision check-ups are NB
What are the side effects of Pyrazinamide?
Hepatotoxicity and joint pain
Where is rifampicin metabolised?
In the liver
cause autoinduction and potent enzyme inducer
Where is rifampicin eliminated?
Primarily biliary-fecal route
Drug interaction with Rifampicin
Drug-interactions with drugs
metabolised in the liver
* Oral contraceptives & progestin implants (replace with injectable contraceptives)
Describe distribuution of isoniazid
Distribution: wide including the CSF
Explain metabolism of isoniazid
Metabolism in the liver via
acetylation (slow acetylators at
greater risk of neurotoxicity)
Excretion of isoniazid
Inactive metabolites excreted in the urine
Adverse effects of isoniazid
Hepatotoxic
* Neurotoxic (peripheral
neuropathy, seizures, psychosis,
ataxia & optic neuritis)
How to reverse neurotoxic effects of isoniazid
Pyridoxime (vit B6)
Drug interactions with isoniazid
Drug-interactions with drugs
metabolised in the liver (weak
enzyme inhibitor)
When prescribing isoniazid, caution is given in patient with ________________
Epilepsy
Ethambutol distribution
Wide but not in CSF
Metabolism of ethambutol
Metabolism in the liver up to 15%
Ethambutol elimination
Mainly unchanged in the urine. Dose adjustment is key, depending on creatinine clearance
CI of ethambutol
Optic neuritis
3 Cautions when prescribing ethambutol
-renal failure, in
-children under 8 years (visual
symptoms cannot always be monitored),
-hyperuricaemia
Adverse effect of ethambutol
Ocular toxicity – patient self
monitoring (reading fine print),
monitor: colour discrimination
and visual field
Distribution of pyrazinamide
Wide including the CSF
Adverse effect of pyrazinamide
Dose-related hepatotoxicity
Hyperurecaemia (caused by
decreased uric acid clearance)
associated with arthralgia (may precipitate gout)
State 3 wanted outcomes of TB treatment
-Prevent TB transmission
* Cure with minimal problems
* Cure with chronic lung disease
state 3 unwanted outcomes of TB treatment
Transmission of TB
* MDR / XDR
* Death
List types of Drug resistant TB
Mono-resistant TB
* Poly-resistant TB
* MDR-TB
* Rifampicin resistant-TB (RR-TB)
* Resistance to at least rifampicin
* Extensively drug-resistant TB (XDR-TB)
* Pre-XDR-TB
What is MDR TB?
In vitro resistance to:
* Rifampicin
* Isoniazid
With or without resistance to other anti-TB drugs
XDR TB definition
MDR TB
+
* In vitro resistance to:
* Any fluoroquinolone
AND
* Any injectable drug
Extremely difficult and expensive to
treat with a high mortality (90%) in
HIV co-infected patients
How to test for isoniazid resistance?
Resistance tests:
* inhA mutation and
* katG mutation
What to use when there is inhA mutation only?
use high dose INH: 10mg/kg/day
What to use when there is katG mutation?
Use ethionamide
T/F: When there is complete resistance (both), use both INH and ethionamide
F
Do not use INH or ethionamide
