Scintigraphic evaluation in rabbits of nasal drug delivery systems based on carbopol 971p (R) and carboxymethylcellulose

The residence time of apomorphine mucoadhesive preparations incorporating T c-99m labeled colloidal albumin in rabbit nasal cavity was evaluated by gam ma scintigraphy. This technique was used to compare the nasal clearance of preparations based either on Carbopol 971P(R) or lactose (control), each wi th and without apomorphine, or carboxymethylcellulose with apomorphine. The planar I-min images showed an excipient-dependent progressive migration of radioactivity with time from the nasal cavity to the stomach and intestine . Thirty minutes post insufflation, the percentages of the formulations cle ared from the nasal cavity were 47% for lactose, 26% for lactose/apomorphin e, 10% for Carbopol 971P(R), and 3% for both Carbopol 971P(R)/apomorphine a nd carboxymethylcellulose/apomorphine. Three hours post insufflation, the p ercentages of the formulations cleared from the nasal cavity were 70% for l actose, 58% for lactose/apomorphine, 24% for Carbopol 971P(R), 12% for Carb opol 971P(R)/apomorphine, and 27% for carboxymethylcellulose/apomorphine. A pomorphine inhibited nasal mucociliary clearance since migration of the rad ioactivity administered with apomorphine containing preparations was in all cases slower than that of the corresponding powder without apomorphine. Th e peak plasma concentration of apomorphine was attained while all the formu lations were still within the nasal cavity. The use of mucoadhesive polymer s such as Carbopol 971P(R) or carboxymethylcellulose in nasal dosage forms increases their residence time within the nasal cavity and provides the opp ortunity for sustained nasal drug delivery. (C) 2000 Elsevier Science B.V. All rights reserved.