AQUEOUS C E L L U L O S I C F I L M C O A T I N G OF T A B L E T S J.E. Hogan, Colorcon L i m i t e d , Sevenoaks Way, Orpington, Kent Aqueous f i l m c o a t i n g o f t a b l e t s h a s been s t e a d i l y i n c r e a s i n g i n p o p u l a r i t y o v e r t h e p a s t few y e a r s . T h i s i s l a r g e l y due t o t h e i n h e r e n t d i f f i c u l t i e s a s s o c i a t e d with t h e s t i l l widely used o r g a n i c s o l v e n t b a s e d p r o c e s s namely: Expense o f s o l v e n t s and measures t h a t have t o be t a k e n t o a v o i d f i r e and explos i o n h a z a r d s ; t h e h e a l t h h a z a r d t o p r o c e s s workers; e n v i r o n m e n t a l p o l l u t i o n and t h e expense o f s o l v e n t r e c o v e r y : ( P i c k a r d and R e e s , 1974, 1976; Lehmann and Dreher 1 9 7 2 ) . T h i s d e m o n s t r a t i o n aims t o p r o v i d e of p h a r m a c e u t i c a l technology v i a a d e t a i l s of equipment, a i r flow and c o a t i n g system f o r m u l a t i o n w i l l b e

a n up t o d a t e p i c t u r e o f t h i s i m p o r t a n t a r e a p r a c t i c a l d e m o n s t r a t i o n i n which e s s e n t i a l t e m p e r a t u r e s , s p r a y equipment d e t a i l s and presented.

I n g e n e r a l , it h a s been shown t h a t a c c e p t a b l e f i l m s c a n be produced u s i n g c e l l u l o s e e t h e r polymers such a s hydroxypropylmethylcellulose, u s u a l l y t h e 5 or 1 5 c p s g r a d e s b u t sometimes as h i g h a s 50 c p s . P l a s t i c i s e r and pigments c a n a l s o b e added a s r e q u i r e d . The t a b l e t s s o produced u s u a l l y have a m a t t appearance compared w i t h t h e t r a d i t i o n a l o r g a n i c s o l v e n t b a s e d p r o c e s s b u t a s h i n e c a n b e i m p a r t e d by applyi n g a s t r a i g h t polymer s o l u t i o n w i t h or w i t h o u t a f i n a l wax p o l i s h i n g a t t h e end of t h e process. Work done h a s shown it p o s s i b l e t o c o a t even m o i s t u r e s e n s i t i v e m a t e r i a l s . V a r i a b l e s e n c o u n t e r e d i n aqueous f i l m c o a t i n g can be a t t r i b u t e d t o :

a) b) c)

Core f o r m u l a t i o n Coating system formulation Spraying c o n d i t i o n s

G e n e r a l l y t h e aqueous c e l l u l o s i c f i l m c o a t i n g p r o c e s s r e q u i r e s t a b l e t c o r e s t o b e r a t h e r l e s s f r i a b l e t h a n r e q u i r e d f o r t h e o r g a n i c s o l v e n t b a s e d p r o c e s s as t h e c o r e s may have t o be tumbled f o r l o n g e r i n t h e a b s e n c e of a p r o t e c t i v e f i l m coat. This i s because s p r a y r a t e i s k e p t down i n o r d e r n o t t o o v e r w e t t h e c o r e s , and l a t e r , t h e f i l m a l r e a d y d e p o s i t e d . B e s i d e s the polymer s o l u t i o n , s p r a y s y s t e m s u s u a l l y r e q u i r e a p l a s t i c i s e r ; p r o p y l e n e g l y c o l and t h e p o l y e t h y l e n e g l y c o l s a r e commonly used h e r e . Pigments and o p a c i f i e r s can be i n c l u d e d i n t h e formula a s f o r s o l v e n t b a s e d c o a t i n g systems. The a b i l i t y o f t h e c o a t i n g equipment t o e v a p o r a t e w a t e r q u i c k l y i s e s s e n t i a l f o r e f f i c i e n t aqueous f i l m c o a t i n g and i n t h i s r e s p e c t p e r i p h e r a l l y v e n t e d p a n s are i d e a l . The a i r t e m p e r a t u r e s h o u l d be t h e maximum p o s s i b l e commens u r a t e w i t h t h e s t a b i l i t y o f t h e c o r e i t s e l f . For t h e b e s t c o a t e d appearance s p r a y r a t e s h o u l d be low and s p r a y d r o p l e t s i z e s h o u l d b e s m a l l and t h i s i s best a c h i e v e d u s i n g a n a i r b o u r n e s p r a y a s opposed t o a n a i r l e s s system. Aqueous c e l l u l o s i c c o a t i n g i n a c o n v e n t i o n a l pan i s q u i t e f e a s i b l e b u t condit i o n s n e e d c a r e f u l watching r e g a r d i n g s p r a y and d r y i n g r a t e s . Lehmann, K . and Dreher, D . ( 1 9 7 2 ) , Pharm. I n d . 34,894. P i c k a r d , J . F . and Rees, J . E . (19741, Manuf. Chem. a n d Aerosol N e w s 45,19. P i c k a r d , J . F . and Rees ,J.E. (1976) , i b i d 47,31.

Aqueous cellulosic film coating of tablets [proceedings].

AQUEOUS C E L L U L O S I C F I L M C O A T I N G OF T A B L E T S J.E. Hogan, Colorcon L i m i t e d , Sevenoaks Way, Orpington, Kent Aqueous f i l m...
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