TB Adverse Drug Reactions Flashcards
Name common side effects of TB drugs
Anorexia, nausea, abdominal pain
Joint pain
Orange urine
Pruritis/rash
Peripheral neuropathy
Which TB drugs are responsible for anorexia, nausea and abdominal pain side effects?
All TB drugs
How do you manage anorexia, nausea and abdominal pain side effects secondary to TB drugs?
- Continue TB drugs
- Give TB drugs at night
- Give anti-emetics
- Exclude liver toxicity
Which TB drug is responsible for joint paint side effects?
Pyrazinamide
How do you manage joint point secondary to pyrazinamide?
Continue TB drugs
NSAIDs if normal eGFR
Which TB drug is responsible for peripheral neuropathy?
INH
How do you manage peripheral neuropathy secondary to INH?
- Continue TB drugs
- Increase pyridoxine to 100mg daily
- Give amitryptiline 25mg note OR gabapentin 300mg tds
- Exclude other causes (DM, renal, B12 deficiency)
Which TB drug is responsible for orange urine?
Rifampicin
How do you manage orange urine secondary to rifampicin?
Reassurance
Which TB drug is responsible for pruritis/rash
All TB drugs
Most common E->P->R->I
Consider ART
Cotrimoxazole
How do you manage pruritis/rash secondary to TB drugs?
Mild - continue therapy, symptomatic treatment
Moderate - rechallenge 1 drug at a time I->R->P->E every 3-5 days
Severe - stop all drugs
What are severe side effects of TB drugs?
Hepatotoxicity
Visual impairment
Thrombocytopenia
Haemolytic anemia
Psychiatric
Seizures
Which TB drugs are responsible for hepatotoxicity?
RIP
What is the management of hepatotoxicity secondary to TB drugs?
- Stop treatment
- LFTs
- Refer
Which TB drugs are responsible for visual impairment?
Ethambutol
Rifabutin
What is the management of visual impairment secondary to TB drugs?
Stop ethambutol
Refer to ophthalmologist
Consider differential (CMV, CCM, toxoplasmosis)
Which TB drugs are responsible for thrombocytopenia or haemolytic anaemia?
Rifampicin
What is the management of thrombocytopenia/hemolytic anaemia secondary to TB drugs?
- Consider differential
- Start rifampicin-sparing regimen
Which TB drugs cause psychiatric side effects?
INH
Terizidone
Ethionamide
Which TB drugs cause seizures?
INH
What is the management of seizures secondary to TB drugs?
Diagnosis of exclusion -> differential diagnosis
Exclude CNS lesion
What is the pattern of injury in pyrazinamide DILI?
Hepatocellular
What is the mechanism of injury in pyrazinamide DILI?
Extensive metabolism by the liver
Dose-related injury suggesting direct toxic effect of drugs/metabolites
What is the pattern of injury in INH DILI?
Hepatocellular
What is the mechanism of injury in INH DILI?
Accumulation of toxic metabolites
Immune mediated component (less common)
What increases risk of INH DILI?
Increasing age
What is the pattern of injury in rifampicin DILI?
Hepatocellular
Cholestatic
Mixed
What is the mechanism of injury in rifampicin DILI?
Extensive metabolism by the liver
Direct toxic effect of metabolites
Immune mediated component
What is the pattern of injury in moxifloxacin DILI?
Hepatocellular
Cholestatic
Mixed
What is the mechanism of injury in moxifloxacin DILI?
Immune mediated component
Which drugs may cause asymptomatic transient elevation in transaminases during hepatic adaptation?
RIP
Moxifloxacin
What are the most important risk factors for hepatotoxicity in individuals on TB treatment?
Alcohol use
Chronic hepatitis infection
HIV coinfection
Extensive TB disease
Malnutrition
Age
? Female
How is drug induced hepatitis defined?
ALT > 120 and symptomatic
OR
ALT > 200 regardless of symptoms
Total serum bilirubin >40
ALT 2x baseline if pre-existing liver disease/ALT>120 pretreatment
What is the management of TB DILI?
- Confirm TB diagnosis
- Check phase of treatment
- Stop all drugs immediately
- Conduct LFTs, hepatitis serology and INR
- Admit to hospital
What is the differential diagnosis for TB DILI?
Alcohol
Pre-existing liver disease
Viral hepatitis
Other drugs
TB of the liver
IRIS
Bacterial sepsis
How do we classify DILI?
Mild (no symptoms, INR<1.5)
Moderate (symptoms, INR<1.5)
Severe (INR>1.5)
What is the management of mild/moderate DILI?
- Hospitalize
- Differential diagnosis
- Pregnancy test
- Abdominal U/S if cholestatic pattern
- ART
If ART<6 months, stop
If ART > 6 months, switch to dolutegravir - Discontinue other hepatotoxic drugs
- Treatment phase
If in intensive phase of treatment, switch to ‘liver friendly’ regimen
If in continuation phase, stop anti-TB treatment until LFTs recover
What is the ‘liver friendly’ TB regimen?
Levofloxacin
Ethambutol
Linezolid
If Hb <8g/dL, what can you consider instead of linezolid for the ‘liver friendly’ TB regimen?
Clofazimine
Terizidone
How do you reintroduced TB drugs in mild/moderate TB DILI?
Monitor ALT and bilirubin 2-3 times weekly
Once ALT <100 with bilirubin on downward trend, reintroduce TB drugs
Day 1. Start INH 300mg daily and stop linezolid
Day 3. Check ALT/bilirubin
Day 4. Add rifampicin 600mg daily
Day 7. Check ALT/bilirubin
Day 8. Stop LFX and ethambutol
Check ALY weekly for 4 weeks and closely monitor for symptoms
At what point can you rule out TB DILI?
If ALT does not improve after 10 days post treatment stopped
Do we rechallenge with pyrazinamide?
No! Assoc with DILI recurrence
Only recommended for TBM or INH/RIF not tolerated
What is the final regimen for patients who don’t tolerate pyrazinamide and developed DILI during intensive phase?
RIE (2 months)
RI (7 months)
What is the final regimen for patients who don’t tolerate pyrazinamide and developed DILI during continuation phase?
RI for 4 months or remainder of continuation phase
What is the final regimen for patients who don’t tolerate INH and developed DILI during intensive phase?
RPE + LFX (6 months)
What is the final regimen for patients who don’t tolerate INH and developed DILI during continuation phase?
Rif + LFX for 4 months or remainder of continuation phase
What is the final regimen for patients who don’t tolerate rifampicin and developed DILI during intensive phase?
BPaL (6 months)
What is the final regimen for patients who don’t tolerate rifampicin and developed DILI during continuation phase?
BPaL for 4 months or remainder of continuation phase
What is the final regimen for patients with TBM who did not tolerate pyrazinamide?
RIE + LFX for 12 months
What is the final regimen for patients with TBM who did not tolerate INH?
RPE + LFX for 12 months
Which drugs does rifampicin reduce the concentration of?
- ART (lopinavir/ritonavir/DTG)
- Azoles
- Corticosteroids
- OCPs
- Warfarin
- Anticonvulsants
- Cyclosporin
- Cardiovascular
- Theophylline
- Sulfonylurea
- Methadone
Why does rifampicin interact with many drugs?
Induces CYP450 -> increased metabolism -> less drug
Why does INH interact with many drugs?
Inhibits CYP450 -> decreased metabolism -> more drug
Which drugs does INH increase the concentration of?
Antiepileptics
Warfarin
Corticosteroids
Theophyllin
Disulfiram
EFV in some patients