Canine treatment with SnET2 for photodynamic therapy
Photodynamic therapy is a treatment technique that utilizes the photoactived species of a drug to destroy tumor tissue. To be successful, the drug must localize in tumor tissue preferentially over normal tissue and must be activated by light of a specific wavelength. Currently the only drug to be approved for clinical use is Hematoporphyrin Derivative (HpD) although a series of new drugs are being developed for use in the near future. One of the drugs belongs to a class called purpurins which display absorptions between 630-711 nm. Along with several other investigators, we are currently exploring the characteristics of a specific purpurin (SnET2) in normal and tumorous canine tissue. The use of this compound has demonstrated increased tumor control rates in spontaneous dog tumors. Preliminary pharmacokinetic studies have been performed on 6 normal beagle dogs. SnET2 (2 mg/kg) was injected intravenously over 10 minutes and blood was collected at 5, 15, 30, 45 minutes and at 1, 2, 4, 8, 12 and 24 hours following administration for determin-ation of drug concentration and calculation of pharmacokinetic parameters. Skin biopsies were collected at 1, 4, 8, 12 and 24 hours. Dogs were euthanized at 24 hours and tissues (liver, kidney muscle, esophagus, stomach, duodenum, jejunum, ileum, colon, adrenal gland, thyroid, heart, lung, urinary bladder, prostate, pancreas, eye, brain) were collected for drug measurement. Drug was shown to persist in liver and kidney for a prolonged period of time compared to other tissues. Knowledge of the pharmacokinetic properties of the drug will greatly add to the ability to treat patients with effective protocols.
