Precautions and warnings

Stop all medications right away if you notice any signs of an allergic reaction. If you need to start isoniazid again, wait until the symptoms are completely gone. Begin with a very small dose and slowly increase it. If any allergy signs return, stop the drug immediately.

Isoniazid should be used with extra care in the following groups:

- People who drink alcohol every day, because they have a higher risk of liver problems.
- Anyone with liver disease or serious kidney problems.
- People over 35 years old.
- Those taking other medications regularly.
- Individuals who have previously had to stop isoniazid.
- People with nerve problems or risks for nerve damage.
- Pregnant women.
- People who use injection drugs.
- Women from minority groups, especially soon after childbirth.
- People who are HIV positive.

Drug Interactions

Rifampicin can make hormonal contraceptives less effective. If taken with antacids, its absorption may be reduced. It can also lower the levels of certain antiviral drugs (such as atazanavir, darunavir, and fosamprenavir) and the medicine atovaquone, especially when used together with rifampicin.

Rifampicin may reduce the effectiveness of many other medicines, including:
- Anticonvulsants (like phenytoin)
- Antiarrhythmics (like disopyramide)
- Blood thinners
- Antifungals (like ketoconazole)
- Barbiturates
- Beta-blockers
- Calcium channel blockers (like diltiazem)
- Some antibiotics (like chloramphenicol and clarithromycin)
- Corticosteroids and ciclosporin
- Heart medicines (such as cardiac glycosides and clofibrate)
- Dapsone
- Sedatives (like diazepam)
- Doxycycline and other antibiotics (like fluoroquinolones, e.g., ciprofloxacin)
- Antipsychotics (like haloperidol)
- Diabetes medicines (sulfonylureas)
- Levothyroxine
- Painkillers (like methadone and narcotic analgesics)
- Progestins and quinine
- Immunosuppressants (like tacrolimus)
- Theophylline (for asthma)
- Certain antidepressants (TCAs, e.g., amitriptyline, nortriptyline)
- Zidovudine (for HIV)

There is also a higher risk of liver damage if rifampicin is used with halothane.

Isoniazid can slow down the breakdown of several drugs, including:
- Anticonvulsants (like carbamazepine and phenytoin)
- Benzodiazepines (like diazepam)
- Haloperidol
- Ketoconazole
- Theophylline
- Warfarin

When taken with isoniazid, medicines like meperidine, cycloserine, and disulfiram may cause stronger side effects on the nervous system. Isoniazid can also make it harder to control blood sugar in people who take medicine for diabetes.

**Warning:** Taking saquinavir with ritonavir at the same time as rifampicin can cause severe and potentially life-threatening liver damage.

Contraindications

Do not use this medication if you are allergic or sensitive to rifamycins, INH, or any of the other ingredients. Also, avoid using it if you have ever had drug-induced hepatitis, if you currently have any serious liver disease, or if you have or have had peripheral neuritis (nerve inflammation).

Mode of actions

Rifampicin and isoniazid are powerful antibiotics used to treat tuberculosis (TB). They work well against TB bacteria that are growing quickly outside cells, and they can also kill bacteria inside cells.

Rifampicin works by blocking a key enzyme (RNA polymerase) that bacteria need to make proteins. It targets only the bacterial enzyme and does not affect human cells. If the TB bacteria become resistant to rifampicin, they are usually only resistant to other similar drugs called rifamycins. Rifampicin can also fight TB bacteria that grow slowly or only sometimes.

Isoniazid is especially effective against TB bacteria that are actively growing.

Dosage & Administration

Oral
Tuberculosis
Adult: Each tab contains rifampicin and isoniazid (mg):
50 kg: 2 tab of 300/150 once daily.
Hepatic impairment: Max: 8 mg/kg daily.

Pregnancy & Lactation

Although animal reproduction studies have shown an adverse effect on the fetus and there are no adequate and well-controlled studies in pregnant women, but during pregnancy, this medicine can be used just when definitely required despite potential risks.

Mothers with a newborn baby who have used this drug during the last 3 months of pregnancy may seldom create symptoms including drowsiness, muscle stiffness or shakiness, feeding or breathing troubles, constant crying. If you notice any of these symptoms of your baby's particularly during their first month, tell the doctor immediately.

This medicine passes into breast milk. Talk to your doctor before breastfeeding.

Pack Size & Price