What to do in case of a lichenoid drug rash during Anti-Tuberculosis Treatment (ATT)?

Management of Lichenoid Drug Rash During Anti-Tuberculosis Treatment

In case of a lichenoid drug rash during anti-tuberculosis treatment (ATT), all potentially responsible drugs should be stopped immediately, followed by sequential reintroduction once symptoms resolve to identify the culprit drug. 1

Initial Management

Step 1: Assessment and Drug Discontinuation

• Stop all potentially hepatotoxic anti-TB drugs (isoniazid, rifampicin, pyrazinamide) immediately
• Evaluate severity of the rash:
  • Mild to moderate: Localized lichenoid eruptions with pruritus
  • Severe: Widespread eruptions, mucosal involvement, or systemic symptoms

Step 2: Interim Treatment Decisions

• If patient is clinically stable and TB is non-infectious: Temporarily hold all ATT until rash resolves
• If patient is unwell or has smear-positive TB: Continue ethambutol and add an alternative drug (such as a fluoroquinolone) to maintain TB treatment 2

Step 3: Symptomatic Management

• For mild-moderate reactions:
  • Topical corticosteroids for localized lesions
  • Oral antihistamines for pruritus relief 2
• For severe reactions (Stevens-Johnson syndrome, exfoliative dermatitis):
  • Hospitalization may be required
  • Systemic corticosteroids (0.5-2 mg/kg/day tapered over 4-6 weeks) 2
  • Consider dermatology consultation

Reintroduction Protocol

Step 4: Sequential Drug Reintroduction

Once the rash has completely resolved, reintroduce drugs one by one at 2-3 day intervals:

1. Start with isoniazid:

   • Begin at 50 mg/day
   • Increase to 300 mg/day after 2-3 days if no reaction

2. Add rifampicin (if no reaction to isoniazid):

   • Begin at 75 mg/day
   • Increase to 300 mg after 2-3 days if no reaction
   • Further increase to weight-appropriate dose after another 2-3 days

3. Add pyrazinamide (if no reaction to rifampicin):

   • Begin at 250 mg/day
   • Increase to 1.0 g after 2-3 days
   • Further increase to weight-appropriate dose

4. Add ethambutol (if it was initially stopped):

   • Begin at low dose and gradually increase to full dose 1

Step 5: Management After Identifying Culprit Drug

• Permanently exclude the offending drug from the regimen
• Develop an alternative regimen based on the excluded drug:
  • If pyrazinamide is the offending drug: Continue rifampicin and isoniazid for 9 months with ethambutol for the initial 2 months
  • If isoniazid or rifampicin is the offending drug: Consult TB specialist for alternative regimen 2

Special Considerations

Monitoring During Reintroduction

• Daily clinical assessment for recurrence of rash
• Monitor liver function tests if hepatotoxicity was part of initial reaction
• Be alert for multiple drug hypersensitivity, which can occur in up to 25% of patients 3

Complications to Watch For

• Lichenoid drug eruptions from ATT can sometimes lead to severe complications:
  • Mucosal involvement with erosions
  • Nail dystrophy and potential anonychia 4
  • Progression to erythroderma in rare cases 5

Prevention of Recurrence

• Document the culprit drug in patient's medical record
• Provide patient education about avoiding the identified drug in future
• Consider desensitization only in cases where drug options are severely limited due to resistance patterns 1

Common Pitfalls and Caveats

1. Delayed recognition: Lichenoid drug eruptions can appear weeks to months after starting ATT, unlike other drug rashes that typically appear within days 5

2. Misdiagnosis: Lichenoid drug reactions can be polymorphic and may mimic psoriasis or eczema, requiring biopsy for confirmation in unclear cases 4

3. Premature rechallenge: Reintroducing drugs before complete resolution of the initial reaction increases risk of more severe reactions

4. Inadequate monitoring: Failure to monitor for systemic involvement during reintroduction can lead to missed severe reactions

5. Inappropriate use of antihistamines: Some antihistamines themselves can rarely cause lichenoid reactions 6

By following this structured approach, most patients with lichenoid drug reactions during ATT can be successfully managed with identification of the culprit drug and completion of effective anti-tuberculosis treatment.