The effects of viscous solutions of hyaluronate-sodium of various average molecular weights (MW) on the nasal absorption of vasopressin (AVP) and its analogue, 1-deamino-8-D-arginine vasopressin (1-d-8-DAVP), were examined in rats. Solutions of hyaluronate with MW greater than 3 x 10(5) daltons enhanced the nasal absorption of AVP; solutions of MW 5.5 x 10(4) daltons were not effective. The enhancing effects on the nasal absorption of AVP and 1-d-8-DAVP were dependent on the concentration in the range of 0-1.5% (w/v) hyaluronate (MW 1.4 x 10(6) daltons). The nasal absorption of AVP was increased with this solution at lower pH. Bioavailabilities after nasal administration of AVP and 1-d-8-DAVP in hyaluronate solutions (MW 1.4 x 10(6) and 2 x 10(6) daltons) increased more than 2-and 1.6-fold as compared to nasal administration of AVP and 1-d-8-DAVP in buffer solutions (pH 7.0), respectively. Hyaluronate solution (MW 1.4 x 10(6) daltons) did not affect the ciliary beat frequency of rabbit nasal mucosal membranes in vitro. Therefore, hyaluronate solution may be useful as a vehicle for nasal delivery of AVP and 1-d-8-DAVP.

1. In the present study we examined the effects of a new Ca2+ channel blocker (lomerizine), an antimigraine drug, on cerebral cortical blood flow (CBF) in anaesthetized rats (laser Doppler flowmetry) and on vertebral blood flow in anaesthetized beagle dogs (electromagnetic flowmeter). 2. Lomerizine (1.25-10 mg/kg, p.o.) dose-dependently increased CBF in rats without affecting blood pressure (BP) or heart rate (HR). 3. The plasma concentration of lomerizine (free base) in anaesthetized rats at 30 and 60 min after the initial administration of 5 mg/kg, p.o., time at which there was a significant increase in CBF, was similar to that reported in healthy subjects receiving lomerizine at 10 mg (2 x 5 mg)/day, p.o., a dose that significantly reduces the frequency and mean duration of headache attacks. 4. Flunarizine (10 mg/kg, p.o.) did not increase CBF significantly. Flunarizine (20 mg/kg, p.o.) did not increase CBF, but did decrease BP 30-120 min after its administration. 5. Lomerizine (2.5 and 5 mg/kg, intraduodenally) dose-dependently increased vertebral blood flow in dogs without significantly changing BP or HR. With 10 mg/kg intraduodenal lomerazine, vertebral blood flow remained elevated from 20 to 240 min after administration and BP was decreased from 20 to 120 min. 6. Thus, lomerizine had a greater effect on CBF than on BP and HR and, therefore, it may be clinically effective in conditions associated with circulatory disturbances in the brain, such as migraine, without producing systemic effects (e.g. hypotension) generally seen with other Ca2+ channel blockers.

The effects of proteolytic enzyme inhibitors, aprotinin, soybean trypsin inhibitor and camostat mesilate as absorption enhancers on the transdermal iontophoretic delivery of salmon calcitonin (SCT) have been examined in rats. The dermal absorption of SCT was evaluated with hypocalcaemic effect. Application of SCT (12.5 int. units/rat) onto abdominal skin did not produce any hypocalcaemic effect. This produced a small hypocalcaemic effect with cationic iontophoresis (drug phase, anode; reference phase, cathode; high frequency pulses of 1 V at 10 kHz, 2h). Furthermore, camostat mesilate (1 mM) and aprotinin (10(6) int. units mL-1) enhanced the hypocalcaemic effects on the application of SCT with iontophoresis. These hypocalcaemic effects were highest with the pH 4.0 preparation compared with those of the pH 5.5, pH 7.0 and pH 8.0 preparations. However, soybean trypsin inhibitor did not change the hypocalcaemic effects. This was because the soybean trypsin inhibitor is a relatively high molecular weight peptide (mol. wt 8000) and an anion at used pH, and therefore was not absorbed through rat skins with cation iontophoresis.

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