Shorter Oral Regimen for DR-TB — MD Exam Answer (15 Marks)

Introduction

A. 6–9 Month BPaLM Regimen (PMDT 2025)

Composition

Inclusion Criteria

1. Age ≥14 years, new microbiologically confirmed RR-TB
2. H/o exposure <1 month to Bdq, Lzd and/or Pa in the past
3. H/o exposure >1 month to Bdq, Lzd and/or Pa — with documented sensitivity to those drugs
4. Persons who had not failed treatment with Bdq or Lzd-containing regimen
5. QTcF on ECG: ≤450 ms (males) and ≤470 ms (females)

Exclusion Criteria

• Age <14 years
• Documented resistance to Bdq, Lzd and/or Pa
• Significant liver dysfunction: LFT (liver enzymes and/or total bilirubin) >3× Upper Limit of Normal
• Severe extrapulmonary MDR-TB: CNS TB, spinal/skeletal TB, disseminated TB
• Pregnant and lactating/breastfeeding women
• Significant cardiac conduction abnormalities: structural heart disease, syncope, long QT syndrome, AV blocks, re-entry arrhythmias; asymptomatic QTcF >500 ms; uncontrolled arrhythmia; history of Torsade de Pointes risk factors (heart failure, hypokalemia, family history of LQTS)

Linezolid Dose Reduction Rules

• All efforts must be made to continue Lzd 600 mg throughout
• If Lzd 600 mg cannot be continued due to severe/Grade 3 toxicity within 9 weeks → regimen declared failed
• Dose reduction to Lzd 300 mg can be considered only after 9 weeks for Grade 3 toxicity
• If Lzd dose is reduced to 300 mg → regimen extended to 39 weeks
• If Lzd is permanently discontinued at any point → regimen declared failed; initiate a new regimen

Regimen Change as per DST

• BPaLM can be initiated in all eligible MDR-TB patients irrespective of availability of baseline DST
• Mfx is part of BPaLM for the full course, irrespective of FQ resistance at baseline or during treatment
• Regimen change may be considered when DST results become available

Special Situation: HIV Co-infection

• BPaLM can be given regardless of HIV status and CD4 count, provided all other eligibility criteria are met
• Caution when CD4 <100 cells/mm³
• Efavirenz (EFV) induces metabolism → reduces Bdq and Pa exposure → co-administration must be avoided; use Dolutegravir (DTG)
• Ritonavir may increase Bdq exposure → risk of Bdq-related adverse reactions
• Avoid Zidovudine — cross-toxicity (peripheral neuropathy + myelosuppression) with Lzd

Anemia and Lzd Use

• Lzd-containing regimen can be offered if pretreatment Hb is >9 g/dL (correctable to >9 g%)
• Do not offer BPaLM if Hb <8 g/dL and anaemia cannot be rapidly corrected
• Lzd not suitable if neutrophils <0.75×10⁹/L or platelets <100×10⁹/L

Pyridoxine Supplementation

Follow-up Monitoring

• Regular clinical, radiological, ECG, biochemical investigations
• If QTcF >450–500 ms (males) or >470–500 ms (females) at baseline → daily ECG for initial 3 days or as per cardiologist's advice
• At month 2: if patient deteriorates or shows no improvement → send specimen for NAAT MTB/XDR or SL-LPA to assess FQ amplification
• Post-treatment follow-up: 6-monthly for 2 years in every DR-TB patient; at least 3-monthly in the first year if BPaLM was extended to 39 weeks

B. 9–11 Month Shorter Oral Bdq-Containing MDR/RR-TB Regimen (PMDT 2021)

Eligibility Criteria

• RR detected/inferred
• MDR/RR-TB with H resistance detected or inferred based on InhA mutation only OR KatG mutation only (not both)
• MDR/RR-TB with FQ resistance not detected
• No history of exposure to previous treatment with second-line medicines in the regimen (Bdq, Lfx, Cfz, or Lzd as applicable) for >1 month — OR — DST documenting sensitivity
• No exclusion criteria

Exclusion Criteria (Shorter Oral Bdq Regimen)

• H/o exposure >1 month to Bdq, Lfx, Eto, or Cfz (if DST for Bdq, FQ, InhA mutation, Cfz, Z is not available)
• Intolerance or risk of toxicity to any drug in the regimen (including drug–drug interactions)
• Extensive TB disease: bilateral cavitary disease or extensive parenchymal damage; in children <15 yrs — cavities or bilateral disease on CXR
• Severe EPTB: miliary TB, TB meningitis, CNS TB; in children <15 yrs — extrapulmonary forms other than lymphadenopathy
• Pregnant and lactating women
• Children below 5 years

Replacement Sequence for Shorter Oral Bdq-Containing MDR/RR-TB Regimen

Key Principle (PMDT 2021, Slide 84): Need for stopping/replacing any drug in the shorter oral Bdq-containing MDR/RR-TB regimen warrants stopping the regimen entirely. Evaluate the patient to switch to the longer oral M/XDR-TB regimen.

C. 6–9 Month H Mono/Poly DR-TB Regimen (PMDT 2021)

Composition

Duration

• Standard: 6 months
• Extended to 9 months (directly, no monthly extensions) in:
  • Extensive disease
  • Uncontrolled comorbidity
  • Extra-pulmonary TB
  • Smear positive at end of month 4
  • When regimen is modified

Treatment Failure

• Sputum smear positive at end of month 5 or later → declare 'Treatment Failed' → re-evaluate as non-responder

Replacement Sequence for H Mono/Poly DR-TB Regimen (PMDT 2021, Slide 54)

• Additional resistance detected (from SL-LPA/LC-DST results)
• Intolerance/non-availability of any drug
• Emergence of exclusion criteria

Note: Re-initiation or re-registration is not required for regimen modifications during the first 4 months, unless the patient is declared 'treatment failed'. The same registration date continues.

D. Key Drug Interactions & Precautions (Bedaquiline)

• Systemic moderate/strong CYP3A4 inhibitors: azole antifungals (ketoconazole, voriconazole, itraconazole, fluconazole), telithromycin, macrolides >2 consecutive weeks
• Systemic strong CYP3A4 inducers: phenytoin, carbamazepine, phenobarbital
• St. John's Wort and rifamycins (rifampin, rifabutin, rifapentine)
• Statin class (cholesterol-lowering medications)

E. Treatment Algorithm (Decision Flow)

Rifampicin resistance detected
        ↓
FL-LPA + SL-LPA + LC-DST (Z, Bdq, Cfz, Mfx, Lzd, Dlm)
        ↓
No additional resistance OR H resistance (KatG or InhA — not both) + FQ not resistant
        → Shorter Oral Bdq-containing MDR/RR-TB regimen (9-11 months)
           OR BPaLM (6-9 months) if ≥14 years
        ↓
H resistance with BOTH KatG + InhA mutation OR FQ resistance detected
        → Longer oral M/XDR-TB regimen

During shorter regimen:
Additional resistance / intolerance / unavailability / exclusion criteria emerge
        → Switch to Longer Oral M/XDR-TB regimen (modified per replacement table)

Summary Table