Gastrostomy tube placement for long-term oral drug administration in non-human primates

Non-human primates (NHPs) are often used as recipients in preclinical transplantation research that in most cases involves administration of various drugs including immunosuppressants. Long-term oral drug administration, particularly tacrolimus, is challenging in the transplant recipient NHPs. Oral drug administration method using the mixture of drug and fruit juice has been used in NHPs, but this is not always effective in all monkeys. To those monkeys who are poorly compliant, oral drug administration in restraint or administration using gastrostomy tube should be necessary. The aim of this study was to compare the efficacy of between oral drug administration in restraint and administration using gastrostomy tube and to report complications and solutions to overcome the problems related to gastrostomy tube for long-term oral drug dosing in rhesus monkeys.

Fifteen of 4- to 5-year-old male and female healthy rhesus monkeys weighing 5.0-6.8 kg were used as recipients for porcine pancreatic islet transplantation. Oral drug administration in restraint was used for four monkeys, and gastrostomy tube was placed to other 11 monkeys (8-French Feeding tube, n=6; Tri-Funnel Replacement Gastrostomy tube, n=5). Oral immunosuppressive drugs such as sirolimus and tacrolimus were administered through the tube. The efficacy and the extent of ease for administration and related complications were compared between two groups.

The complication of gastrostomy included a transient inflammation in the skin and peritonitis caused by a leakage around implantation site (one case), which could be overcome by changing suture method and tube type to interlocking box suture and Tri-Funnel Replacement Gastrostomy tube, respectively. Despite these complications, oral drug administration using gastrostomy tube allowed us to perform accurate dosage of drug administration and to reduce the stress that both the monkey and the researcher may experience. Taken together, this study showed that gastrostomy tube placement is a better alternative to oral drug administration in restraint for long-term oral drug administration in rhesus monkeys who tend to refuse to eat the mixture of drug and fruit juice.