A 28-year-old woman with newly diagnosed pulmonary tuberculosis is found to be pregnant (8 weeks gestation). Which drug should be AVOIDED in the standard first-line TB regimen during pregnancy?

Explanation

## Anti-TB Drug Safety in Pregnancy **Key Point:** Pyrazinamide is contraindicated in pregnancy due to teratogenic potential and lack of sufficient safety data in the first trimester. The modified regimen for pregnant TB patients is **2HRZE/4HR** (without Z in intensive phase). **High-Yield:** In pregnant patients with TB: - **Avoid:** Pyrazinamide (PZA) — teratogenic; streptomycin (ototoxic, 8th cranial nerve damage) - **Safe:** Isoniazid, rifampicin, ethambutol — all Category A/B in pregnancy - **Modified intensive phase:** 2HRE (without Z) × 2 months - **Continuation phase:** 4HR × 4 months - **Total duration:** 6 months (same as non-pregnant, but without pyrazinamide) ## Safety Profile of First-Line Drugs in Pregnancy | Drug | Pregnancy Category | Safety | Notes | |------|-------------------|--------|-------| | **Isoniazid** | A | Safe | No teratogenic effects; crosses placenta but safe | | **Rifampicin** | C | Safe | Extensive use in pregnancy; no adverse effects | | **Pyrazinamide** | X / Avoid | **UNSAFE** | Teratogenic potential; inadequate safety data | | **Ethambutol** | B | Safe | Good safety record; monitor visual acuity | | **Streptomycin** | D | **UNSAFE** | 8th nerve damage; permanent deafness in fetus | **Clinical Pearl:** The WHO and most guidelines recommend using HRE (without Z) in the intensive phase for pregnant TB patients. While some recent data suggest pyrazinamide may be safe, it remains contraindicated in most Indian and international guidelines due to historical concerns and lack of definitive safety data. **Mnemonic:** **SAFE in pregnancy** = **S**kip pyrazinamide, **A**void streptomycin, **F**ocus on H-R-E, **E**thambutol is okay ## Treatment Regimen Comparison ```mermaid flowchart TD A[TB Diagnosis]:::outcome --> B{Patient Pregnant?}:::decision B -->|No| C[Standard: 2HRZE/4HR]:::action B -->|Yes| D[Modified: 2HRE/4HR]:::action C --> E[6 months total]:::outcome D --> F[6 months total<br/>Omit Z in intensive phase]:::outcome G[Avoid: Pyrazinamide<br/>Avoid: Streptomycin]:::urgent ``` **Warning:** ~~Pyrazinamide is safe in pregnancy~~ — this is a common misconception. Although some recent literature questions the teratogenic risk, standard guidelines and Indian TB protocols still recommend avoiding it in pregnant patients. [cite:Park 26e Ch 8; RNTCP Guidelines] **Tip:** In NEET PG exams, when a pregnant TB patient is presented, the expected answer is always the **modified 2HRE/4HR regimen** (without Z). This is the standard of care in India.