The appropriate dose of MEKINIST has not been established in patients with moderate or severe hepatic impairment.

8.8 Renal Impairment
No formal clinical study has been conducted to eva luate the effect of renal impairment on the pharmacokinetics of trametinib. No dose adjustment is recommended in patients with mild or moderate renal impairment based on a population pharmacokinetic analysis [see Clinical Pharmacology (12.3)]. The appropriate dose of MEKINIST has not been established in patients with severe renal impairment.

10 OVERDOSAGE
There were no reported cases of inadvertent overdosage with MEKINIST. The highest doses of MEKINIST eva luated in clinical trials were 4 mg orally once daily and 10 mg administered orally once daily on two consecutive days followed by 3 mg once daily. In seven patients treated on one of these two schedules, there were two cases of retinal pigment epithelial detachments for an incidence of 28%. Since trametinib is highly bound to plasma proteins, hemodialysis is likely to be ineffective in the treatment of overdose with MEKINIST.

11 DESCRIPTION
Trametinib dimethyl sulfoxide is a kinase inhibitor. The chemical name is acetamide, N-[3-[3-cyclopropyl-5-[(2-fluoro-4- iodophenyl)amino]-3,4,6,7-tetrahydro-6,8-dimethyl- 2,4,7-trioxopyrido[4,3-d]pyrimidin-1(2H)-yl]phenyl]-, compound with 1,1’-sulfinylbis[methane] (1:1). It has a molecular formula C26H23FIN5O4•C2H6OS with a molecular mass of 693.53. Trametinib dimethyl sulfoxide has the following chemical structure:

Trametinib dimethyl sulfoxide is a white to almost white powder. It is practically insoluble in the pH range of 2 to 8 in aqueous media.

MEKINIST (trametinib) Tablets are supplied as 0.5-mg, 1-mg, and 2-mg tablets for oral administration. Each 0.5-mg tablet contains 0.5635 mg trametinib dimethyl sulfoxide equivalent to 0.5 mg of trametinib non-solvated parent. Each 1-mg tablet contains 1.127 mg trametinib dimethyl sulfoxide equivalent to 1 mg of trametinib non-solvated parent. Each 2-mg tablet contains 2.254 mg trametinib dimethyl sulfoxide equivalent to 2 mg of trametinib non-solvated parent.

The inactive ingredients of MEKINIST Tablets are: Tablet Core: mannitol, microcrystalline cellulose, hypromellose, croscarmellose sodium, magnesium stearate (vegetable source), sodium lauryl sulfate, colloidal silicon dioxide. Coating: hypromellose, titanium dioxide, polyethylene glycol, polysorbate 80 (2-mg tablets), iron oxide yellow (0.5-mg tablets), iron oxide red (2-mg tablets).

12 CLINICAL PHARMACOLOGY
 
12.1 Mechanism of Action
Trametinib is a reversible inhibitor of mitogen-activated extracellular signal regulated kinase 1 (MEK1) and MEK2 activation and of MEK1 and MEK2 kinase activity. MEK proteins are upstream regulators of the extracellular signal-related kinase (ERK) pathway, which promotes cellular proliferation. BRAF V600E mutations result in constitutive activation of the BRAF pathway which includes MEK1 and MEK2. Trametinib inhibits BRAF V600 mutation-positive melanoma cell growth in vitro and in vivo.

12.2 Pharmacodynamics
Administration of 1 mg and 2 mg trametinib to patients with BRAF V600 mutation-