Pemfexy Disease Interactions

Pemetrexed can cause severe myelosuppression resulting in the need for transfusion and which may lead to neutropenic infection. The risk of myelosuppression is increased in patients who do not receive vitamin supplementation (including oral folic acid and IM vitamin B12). Patients with myelosuppression should be monitored carefully. A CBC should be obtained at the beginning of each cycle and as needed. Treatment should not be initiated unless the absolute neutrophil count is at least 1500 cells/mm3 and platelet count is at least 100,000 cells/mm3.

Serious interstitial pneumonitis (including fatal case) can occur with pemetrexed. Care should be exercised when using pemetrexed in patients with preexisting pulmonary impairment. Pemetrexed should be withheld for acute onset of new/progressive unexplained pulmonary symptoms; if pneumonitis is confirmed, pemetrexed should be permanently discontinued.

Pemetrexed can cause severe (and sometimes fatal) renal toxicity. Pemetrexed is primarily eliminated by the kidneys; decreased renal function results in decreased clearance and increased pemetrexed exposure compared with normal renal function. No dose is recommended for patients with CrCl less than 45 mL/min. CrCl should be determined before each dose and renal function should be monitored periodically during therapy. Pemetrexed should be withheld in patients with renal toxicity until CrCl is 45 mL/min or greater.

No formal studies have been conducted to examine pemetrexed in patients with liver dysfunction. Caution is advised.

Radiation recall can occur with pemetrexed in patients who have received radiation weeks to years previously. Patients should be monitored for inflammation/blistering in areas of previous radiation treatment; they should be advised to immediately contact their health care provider if inflammation/blisters develop in a previously irradiated area. Pemetrexed should be permanently discontinued for signs of radiation recall.