Prophylaxis of drug-susceptible TB is effective when properly done. It may reduce the risk of developing TB by up to 90% in a patient with primary infection.
– It is often difficult to rule out active TB with certainty, but it is essential to do so; administering prophylaxis to a patient with active TB would be the equivalent of giving the patient isoniazid in monotherapy.
– Most studies reveal poor adherence (28-60%)2,3, since asymptomatic patients do not see the point of what they consider a long, restrictive treatment.
– The effectiveness of prophylaxis depends on the strain sensitivity to isoniazid.
– The risk of isoniazid-induced hepatitis is not insignificant. It is low in young subjects and progressively increases with age, attaining over 2% in subjects over 50 years4.
– Isoniazid is contraindicated in patients with severe or chronic active hepatitis. It should be administered with caution to patients who regularly consume alcohol.