Efudex Long-term Side Effects

Efudex is a topical cream used in the treatment of actinic keratoses (or solar keratoses) and superficial basal cell carcinoma. The active ingredient of this medication is fluorouracil. Fluorouracil is a chemical compound that interferes with the synthesis of deoxyribonucleic acid (DNA) and ribonucleic acid (RNA). By interfering with a cell's ability to produce these important components, fluorouracil halts the growth of cancerous cells.

Carcinogenesis and Mutagenesis

Although there have been no adequate long-term studies to evaluate the carcinogenic potential of Efudex, Valeant Pharmaceuticals acknowledges that studies of 5-fluorouracil (the main ingredient of Efudex) have revealed positive results for mutagenicity (an origin for the mutation of cells in the body). It is common for anti-cancer medications to test positive for carcinogenesis and mutagenesis due to the methods they employ to stop cancer. In order for Efudex to be effective, it must kill off cancerous cells in a localized area. However, Efudex destroys cells indiscriminately and cannot tell cancerous cells from healthy cells in the localized area. This could lead to cells mutating and the rise of another form of cancer.

Impairment of Fertility

According to Valeant Pharmaceuticals, fluorouracil has been shown to cause changes in chromosome organization of spermatogonia of rats. This results in killed spermatogonia and spermatocytes, leading to intransient infertility. In female rats, the incidence of fertile mating was reduced and pre-implantation lethality was increased. Although the test was on rats, it is commonly accepted in the medical community that the mammalian birth process in rats and humans is similar. It can be assumed that infertility in rats is accurately translated to humans. RxList also notes that birth defects leading to miscarriage and VSD (ventricular septal defect) can occur with application of Efudex. VSD is a very dangerous birth defect of the heart.

Life-Threatening Toxicity

Although it is rare, life-threatening toxicities may occur with intravenous use of this medication. According to Valeant Pharmaceuticals, the most commonly reported toxicities are stomatitis, diarrhea, neutropenia (a decrease in number of white blood cells essential for immune functions) and neurotoxicity. This is experienced by patients with DPD (dihydropyrimidine dehydrogenase) deficiency. This is due to the fact that DPD is the enzyme used to metabolize uracil. Though it is not known whether or not patients with DPD deficiency would suffer these side effects when Efudex is used topically, it is still suggested that patients with DPD deficiency exercise caution when applying this medication. This caution is especially echoed around open wounds. According to RxList, herpes simplex can also be obtained from the use of Efudex. This can be considered a secondary effect due to the loss of immune functions. In a patient with low immune functions herpes simplex can prove to be very dangerous.