The
TB Working Group discuss INH and liver damage;
Over the last month, a few reports about new positive TB cases have surfaced from FL, involving students at a couple of high schools and at a college.
So what do you treat positive TB cases with - INH?
INH inhibits an enzynme, InhA, which is involved in fatty acid synthesis. A recent
Morbidity and Mortality Weekly Report (MMWR) published in the Journal of the American Medical Association (
JAMA) by the
CDC reports the incidence of severe liver toxicity in patients receiving INH treatment for LTBI.
Compliance
presents a problem
9 months of INH therapy remains the mainstay of LTBI treatment.
Whilst INH therapy
should be carefully monitored
No more than a 1-month supply of INH at a time should be prescribed, and treatment should be combined with careful clinical monitoring
monitoring is not 100% effective
despite adherence to current guidelines for monitoring, liver injury occurred
and symptoms of damage are not sufficient
In the absence of symptoms, isoniazid should be discontinued if aminotransferase values are five times the upper limit of normal.
Lee Reichman
responds
It seems to me that the bottom line is that treatment of latent infection has always been toxic, that’s why we use targeted treatment, concentrating on those patients in whom treatment is necessary (contacts, immunosuppressed).
At our institute, we have been using Rifampin for 4 months [Reichman LB, Lardizabal A, Hayden: 2004 Am J Respir Crit Care Med 170 832-835;107. Lardizabal AA, Passannante M, Kojakali F, Hayden C, Reichman LB. 2006 Chest; 130:1712-1717.] with far less toxicity and far more compliance.
Also, the skin test is overly unspecific, consequently, many patients are treated who aren’t infected or at risk for TB. Exclusive use of IGRAS would obviate this immediately.
Exactly
