Chemo prophylaxis of tuberculosis pharmac 2nd year
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tuberculosis AND preventive therapy
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WHO consolidated guidelines tuberculosis preventive treatment 2024 recommended regimens
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https://www.who.int/publications/i/item/9789240096196
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India National TB Elimination Programme TB preventive treatment 3HP isoniazid rifapentine contacts guidelines
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Chemoprophylaxis of tuberculosis
Chemoprophylaxis, now called tuberculosis preventive treatment (TPT), means giving anti-TB drugs to persons with TB infection or high-risk exposure after excluding active TB disease, to prevent development of active tuberculosis.
Principle
- It is meant for latent TB infection, not active TB.
- Never give isoniazid alone if active TB is suspected, because it can select drug-resistant organisms.
- Before starting: screen for symptoms of TB, examine the patient, and investigate for active disease when indicated.
The WHO’s current terminology and recommendations are in its 2024 TPT guideline.
Indications
TPT is considered in persons at high risk of progression from infection to active TB:
-
Household/close contacts of a person with bacteriologically confirmed pulmonary TB, especially:
- Children under 5 years
- Adolescents and adults with TB infection after evaluation
-
People living with HIV (PLHIV), once active TB has been excluded.
-
Other high-risk groups, depending on national policy:
- Silicosis
- Patients receiving immunosuppressive therapy, especially anti-TNF drugs
- Dialysis/chronic renal failure
- Transplant candidates or recipients
- Recent TB test converters
- Health-care workers or other persons with significant exposure
For India, the NTEP lists 3HP and 6H as preventive-treatment options. See the NTEP TPT guidance.
Regimens
| Regimen | Drugs | Duration | Comment |
|---|---|---|---|
| 6H | Isoniazid daily | 6 months | Traditional and commonly used regimen |
| 9H | Isoniazid daily | 9 months | Alternative where appropriate |
| 3HP | Isoniazid + rifapentine once weekly | 3 months | Short-course regimen with better completion |
| 3HR | Isoniazid + rifampicin daily | 3 months | Alternative short regimen |
| 4R | Rifampicin daily | 4 months | Useful if isoniazid cannot be used |
| 1HP | Isoniazid + rifapentine daily | 1 month | Mainly used for selected persons with HIV, according to policy |
Short rifamycin-based regimens are generally preferred when feasible because completion is better. Lippincott lists 3HP, 4R, and 3HR as key LTBI regimens.
Isoniazid preventive therapy
Dose
- Adults: isoniazid 5 mg/kg/day, maximum 300 mg/day
- Children: isoniazid 10 mg/kg/day (range 7-15 mg/kg), maximum 300 mg/day
- Duration: usually 6 months in the Indian program, or 6-9 months depending on guideline and patient group.
Pyridoxine supplementation
Give pyridoxine (vitamin B6), 25-50 mg/day with isoniazid, especially in:
- Pregnancy
- HIV infection
- Diabetes mellitus
- Alcohol dependence
- Malnutrition
- Chronic renal failure/dialysis
- Elderly persons
- Existing peripheral neuropathy
It prevents isoniazid-induced peripheral neuropathy. Katzung’s Basic and Clinical Pharmacology, 16th ed., section “Clinical Uses” recommends pyridoxine 25-50 mg/day in those predisposed to neuropathy.
Adverse effects and monitoring
Isoniazid
- Hepatitis/hepatotoxicity
- Peripheral neuropathy
- Rash, fever
- CNS toxicity or seizures rarely
- Drug interactions, for example increased carbamazepine concentration
Rifampicin/rifapentine
- Hepatotoxicity
- Gastrointestinal upset
- Rash or flu-like syndrome
- Orange-red discoloration of urine, tears, and body fluids
- Major drug interactions due to enzyme induction, including with some antiretroviral drugs and oral contraceptives
Monitoring
- Ask at every visit about anorexia, nausea, vomiting, fatigue, dark urine, jaundice, rash, tingling, or numbness.
- Baseline liver tests are particularly important in those with liver disease, regular alcohol intake, HIV, pregnancy/postpartum status, or use of other hepatotoxic drugs.
- Stop the drug and evaluate promptly if symptoms of hepatitis occur.
Exam points
Definition:
Chemoprophylaxis of TB is administration of antitubercular drugs, most commonly isoniazid, to persons with latent TB infection or high-risk exposure after excluding active TB, to prevent progression to active disease.
Chemoprophylaxis of TB is administration of antitubercular drugs, most commonly isoniazid, to persons with latent TB infection or high-risk exposure after excluding active TB, to prevent progression to active disease.
Drug of choice:
Traditionally, isoniazid.
Traditionally, isoniazid.
Classical regimen:
Isoniazid daily for 6 months, with pyridoxine supplementation.
Isoniazid daily for 6 months, with pyridoxine supplementation.
Most important precaution:
Exclude active tuberculosis before starting preventive therapy.
Exclude active tuberculosis before starting preventive therapy.
Current trend:
Use of shorter rifamycin-containing regimens such as 3HP where available.
Use of shorter rifamycin-containing regimens such as 3HP where available.
Recent evidence update: A 2024 systematic review and individual-participant meta-analysis supports preventive treatment among TB contacts across age groups and infection-test categories (PMID: 38734022). WHO’s 2024 update also includes preventive treatment for contacts of MDR/RR-TB, using appropriate drug-resistance-guided regimens.
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