An extended release dosage composition of pharmaceutically active substances
that
have a water contact angle () such that cos is between +0.9848 and
-0.9848 presented as a matrix tablet containing the said pharmaceutically active
substances, with/without suitable pharmaceutical excipients in intimate mixture
with two groups of intelligent polymers having opposing wettability characteristics,
one demonstrating a stronger tendency towards hydrophobicity and the other a stronger
tendency towards hydrophilicity, the polymer combination being between the ratios
of 1:50 and 50:1 amounts effective to control the release of said pharmaceutically
active substances in a mathematically predictable manner, wherein the polymer demonstrating
a stronger tendency towards hydrophobicity is not less than 5% wt/wt and preferably
between 5-70% wt/wt of the final formulation composition. The intelligent polymers
being ethylcellulose (EC) as a more strongly hydrophobic and hydroxyethylcellulose
(HEC) and/or hydroxypropyl methylcellulose (HPMC) as more strongly hydrophilic
(the ratio of HEC to HPMC being between 1:100 and 100:1). The matrix tablet is
optionally coated with an enteric coat, 0-5%-15% wt/wt to prevent the initial burst
effect seen in such systems and to impart gastrointestinal tract (GIT) "stealth"
characteristics especially in the presence of food.
