mTOR INHIBITORS Sirolimus This new and potent immunosup-pressant is a macrolide antibiotic (like tacrolimus), which was earlier named Rapamycin. Mech of action:- It binds to immunophillin FKBP and the sirolimus-FKBP complex inhibits kinase called 'mammalian target of rapamycin' (mTOR). uses:- 1)For prophylaxis and therapy of graft rejection reaction, sirolimus can be used alone, but is generally combined with lower dose of cyclosporine/tacrolimus and/or coicosteroids and mycophenolate mofetil. It is paicularly suitable for patients developing renal toxicity with cyclosporine.( Sirolimus is non nephrotoxic). 2)sirolimus coated stents are being used to reduce the incidence of coronary aery restenosis, by inhibiting endothelial proliferation at the site. Adverse effects:- Significantly, sirolimus is not nephrotoxic, but it can suppress bone marrow, mainly causing thrombocytopenia. Rise in serum lipids is common. Other adverse effects are diarrhoea, liver damage and pneumonitis. Ref:- kd tripathi; pg num:-882