Vitamins E and A increase the passing of the P-gp substrate ivermectin into the brain in mice.

This study aimed to determine the effect of administration of oral vitamins A and E at different doses on plasma and brain concentrations of ivermectin in mice. The study was carried out on 174 Swiss Albino male mice aged 8-10 weeks. After leaving six mice for method validation, the remaining mice were randomly divided into seven groups with equal numbers of animals. Mice received ivermectin (0.2 mg/kg, subcutaneous) alone and in combination with low (vitamin A: 4000 IU/kg; vitamin E: 35 mg/kg) and high (vitamin A: 30 000 IU/kg; vitamin E: 500 mg/kg) oral doses of vitamins A and E. The plasma and brain concentrations of ivermectin were measured using high-performance liquid chromatography-fluorescence detector. We determined that high doses of vitamins A and E and their combinations increased the passing ratio of ivermectin into the brain significantly. The high-dose vitamin E and the combination of high-concentration vitamins E and A significantly increased the plasma concentration of ivermectin (P < 0.05). The high-dose vitamins E and A and their high-dose combination increased the brain concentration of ivermectin by 3, 2, and 2.7 times, respectively. This research is the first in vivo study to determine the interaction between P-gp substrates and vitamins E and A.

Formulation Studies of Solid Self-Emulsifying Drug Delivery System of Ivermectin.

BACKGROUND: The suggested dose of ivermectin is 300 µG/kg/day for onchocerciasis but it has low water solubility and poor oral bioavailability. AIM: To prepare and evaluate a solid lipid-based self-emulsifying drug delivery system of ivermectin. MATERIALS AND METHODS: Based on supersaturated solubility study, oil, surfactant, and co-surfactant were selected. On the basis of ternary phase diagrams and simplex-lattice design, self-emulsifying, drug delivery formulations had been developed and optimized. Ivermectin-excipients compatibility studies were performed using differential scanning calorimetry and Fourier transform infrared spectroscopy. Solid self-emulsifying drug delivery formulation was formulated from the optimized batch by surface assimilation method and filled into hard gelatin capsules. In vitro release rate and in vivo pharmacokinetic parameters of ivermectin from the capsules were determined. Two-tailed paired t-test/Dunnett multiple comparison tests were performed for in vivo pharmacokinetic parameter at 95 % of confidence level. RESULTS: Soybeans oil, tween 80, and span 80 were selected as oil, surfactant, and co-surfactant respectively. The ternary diagrams were shown the maximum area for emulsion in 1:2 surfactant/co-surfactant ratio. The optimized batch had found with 30 mg ivermectin, 6.17 g soybeans oil, 0.30 g tween 80, and 3.50 g span 80. All differential scanning calorimetry and Fourier transform infrared characteristic peaks of the optimized formulation were identical with that of pure ivermectin. The area under the curve of ivermectin from the capsule was about two-fold higher than that of ivermectin suspension. CONCLUSIONS: Solid self-emulsifying drug delivery system was an effective oral solid dosage form to improve the oral bioavailability of ivermectin.

The effect of sesame and sunflower oils on the plasma disposition of ivermectin in goats.

The effect of sesame oil (SSO) and sunflower oil (SFO) (the excipients) on the plasma disposition of ivermectin (IVM) following intravenous (i.v.) and subcutaneous (s.c.) administration at a dosage of 200 microg/kg was investigated in goats. Ten clinically healthy crossbred goats were used in the study. The animals were allocated by weight and sex into two groups of five animals each. Group 1 (n = 5) received the drug and excipient by the i.v. route only and group 2 received drug and excipient by the s.c. route only. The study was designed according to a two-phase crossover design protocol. In the first phase three animals in group 1 were i.v. administered IVM (0.2 mg/kg) + SSO (1 mL) and the other two animals received IVM (0.2 mg/kg) + SFO (1 mL). In the second phase animals were crossed over and received the alternate excipient with IVM at the same dosages. In group 2 during the first phase, three animals were s.c. administered IVM (0.2 mg/kg) + SSO (1 mL) and the other two animals were received IVM (0.2 mg/kg) + SFO (1 mL). In the second phase animals were crossed over and received the alternate excipient with IVM at the same dosages. A 4-week washout period was allowed between the two phases. In group 2 significantly increased dermal thickness was observed at the s.c. injection site of the all animals which received IVM during phase I regardless of the excipient. There was almost no change observed at the injection site of any animal during the second phase of the study following s.c. administration. In group 2 the plasma concentrations of IVM in the second phase for both excipient combinations were much higher than the plasma concentrations following first administration and appeared to be related with the dermal changes. The mean plasma disposition of IVM in combination with SSO or SFO was similar following i.v. administration. Longer terminal elimination half-lives and resultant longer mean resident time were observed after s.c. administration of the both combinations compared with i.v. administration.