EFFECTS OF ENTERAL FORMULAS ON METHOTREXATE TOXICITY

Type of diet influences toxic effects of the chemotherapeutic drug met hotrexate (MTX) on the gastrointestinal tract (GI) tract. In this stud y, commercial enteral products containing various protein types were t ested to determine whether they exacerbated or alleviated MTX-induced GI toxicity in a non-tumor-bearing animal model receiving a single inj ection of MTX (20 mg/kg). Five enteral products containing casein or s oy isolate in various forms as the primary source of protein were used . One casein-based product also contained soy fiber. These diets were compared with a soy concentrate-based diet and a casein-based diet pre pared by the authors. Each diet was fed to 10 rats for seven days befo re injection and seven days after injection. In animals fed soy isolat e or hydrolyzed or intact casein without added soy fiber, food intake was <30% of pre-MTX injection levels on Days 3 and 4 after injection. These animals also lost weight and had diarrhea. Rats consuming the ca sein-based diet with fiber experienced some protection against MTX tox icity. Food intake only dropped to 63% of preinjection levels, weight was maintained, and no diarrhea occurred Rats fed soy concentrate main tained food intake above 90% of preinjection levels, which was greater than all other groups at Day 3 and those receiving hydrolyzed or inta ct casein without fiber on Day 4 (p < 0.05). Weight gain in the soy co ncentrate group was also different from that in groups fed hydrolyzed or intact casein without fiber (p < 0.05). Rats consuming soy concentr ate had no diarrhea. A second experiment was conducted to evaluate his tological damage to the intestine when these diets were fed to animals injected with MTX. This experiment was conducted in the same manner a s the first experiment, except animals were sacrificed on Day 3 after injection and samples were obtained from the jejunum. Crypt necrosis o ccurred in all groups except those consuming the soy concentrate diet or the enteral product containing soy fiber. Results indicate that soy concentrate is superior in alleviating MTX toxicity compared with com mercial enteral products.