The pharmacokinetics and pharmacological efficacy of orally (p.o.) administered acepromazine were studied and compared with the intravenous (i.v.) route of administration in a cross-over study using six horses. The oral kinetics of acepromazine can be described by a two-compartment open model with first-order absorption. The drug was rapidly absorbed after p.o. administration with a half-life of 0.84 h, tmax of 0.4 h and Cmax of 59 ng/ml. The elimination was slower after p.o. administration (half-life 6.04 h) than after i.v. injection (half-life 2.6 h). The bioavailability of the orally administered drug formulation was 55.1%. After p.o. administration of 0.5 mg/kg acepromazine, the parameters of the sedative effect were similar to those obtained after i.v. injection of 0.1 mg/kg. The effect of the drug on blood cell count and haemoglobin content was similar after both p.o. administration and injection, while the effects on the parameters of penile prolapse and on the mean arterial blood pressure were less pronounced after p.o. administration than after injection. After p.o. administration, no significant effects on haematocrit-level as well as on the heart and respiratory rates were observed, while these parameters were significantly affected after injection. It is concluded that the high initial plasma level of the drug after i.v. injection may play a role in producing adverse effects of acepromazine.

Summary The pharmacokinetics of ascorbic acid were studied in 29 horses after intravenous (iv), subcutaneous, intramuscular (im) and oral administration. Following iv injection of 5 and 10 g ascorbic acid, respectively, a biphasic decline of ascorbic acid serum levels was found, indicating that the vitamin distributes in the body according to a two‐compartment open model. The apparent volume of distribution (average value for Vd(ss)= 0.6 litre/kg) was approximately equivalent to the volume of total body water. The terminal half‐life of the biexponential serum level‐time curve (t1/2β) varied between 5 and 17 h. Both distribution and elimination were found to be positively correlated with the iv dose administered. Following subcutaneous and im injection, the average bioavailability of ascorbic acid amounted to 82 and 61 per cent, respectively. However, both routes of administration gave rise to marked local irritation. Following oral administration, the systemic availability of ascorbic acid was very poor. Serum levels in most experiments were not increased above the endogenous pre‐administration values of the vitamin. Thus, in horses iv injection appears to be the only satisfactory route of administration of ascorbic acid if supplementation is required.

(–) 15-Deoxyspergualin, originally discovered as an antitumoral drug, was shown to have different immunosuppressive effects, when pancreas and orthotopic allogeneic liver transplantations in rats were compared. In the strong rejection model dark agouti → Lewis (RTl^a → RT1¹) we could only show a minor immunosuppressive effect, as far as pancreaticoduodenal and pancreas segment transplantations are concerned: graft survival was prolonged by 9 days in pancreas segment allografts (p < 0.01) and by 6 days in pancreaticoduodenal allografts (p < 0.01), when recipients were treated by ten doses of 2.5 mg/kg deoxyspergualin. Pretreatment of recipients with 15-deoxyspergualin was not efficient. On the contrary, in orthotopic liver transplantation done by the cuff technique, a remarkable prolongation of allograft survival could be demonstrated: about half of the animals showed prolongation of allograft survival for more than 80 days, compared with about 11 days in the control group (p < 0.01). The substance is considered to be valuable for clinical application.

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