Physical compatibility of pemetrexed disodium with other drugs during simulated Y-site administration

The physical compatibility of pemetrexed disodium with selected other drugs during simulated Y-site injection was studied.

A 5 mL sample of pemetrexed disodium 20 mg/mL in 0.9% sodium chloride injection was combined with 5 mL of a solution of each of 79 other drugs. The other test drugs included antineoplastics, antiinfectives, and supportive care drugs used undiluted or diluted in 0.9% sodium chloride injection or 5% dextrose injection. Visual examinations were performed with the unaided eye in normal diffuse fluorescent light at intervals up to four hours after mixing. Combinations with no obvious incompatibility were examined further with a high-intensity monodirectional light source to enhance visualization of small particles and low-level turbidity. The combinations were also evaluated with a turbidimeter at one and four hours. All combinations without visual incompatibility were assessed with a particle sizer-counter.

Of the 79 pemetrexed-secondary drug combinations, 55 were compatible for at least four hours. However,mixture with 24 drugs resulted in precipitation (including microprecipitation) and color change.

Pemetrexed disodium was incompatible with 24 drugs during simulated Y-site administration and should not be administered with them.