Erythromycin microencapsulated granules

DETAILED DESCRIPTION OF THE INVENTION The invention relates to pharmaceutically active microencapsulated granules comprising erythromycin and a binder.
Such erythromycin granules are particularly useful in flowable material dispensing devices.
One such dispensing device is the "Flowable Material Dispenser" disclosed in U.
S.
Pat.
No.
4,579,256 incorporated herein by reference.
In order for pharmaceutically active granules to be used in the above-described dispenser, such granules must exhibit a high concentration of pharmaceutically active agent, a small size, a narrow size distribution and a uniformity of shape, preferably spherical.
They must also be resilient enough to withstand packaging on high speed filling equipment and shipment throughout the world.
The uniformly spherical granules ensure the accuracy and reproducibility of doses from the dispenser.
The properties of high concentration and small size are necessary for convenience of administration by minimizing the amount of granules the patient has to swallow.
The high concentration and small size, along with the narrow size distribution of uniformly spherical granules are also desirable so that the granules do not create an unpleasant gritty feeling in the patient's mouth when the granules are ingested with the food on which they are dispensed.
Small average size is also necessary if the flowable material dispenser is to be kept small enough to be hand-held and hand-operated.
The erythromycin granules which meet the above concentration, size and shape requirements comprise a starting seed which has an active coating applied thereto.
The active coating comprises erythromycin and a binder.
Erythromycin is a well-known antibiotic which is available as white or slightly yellow crystals or powder.
It is slightly hygroscopic and has a pK.
sub.
a of 8.
7.
Erythromycin is very slightly soluble in water, and freely soluble in alcohol, chloroform, ether and acetone, and moderately soluble in amyl acetate and ethylene dichloride.
Suitable binders for use with the erythromycin include hydroxypropyl methylcellulose phthalate, polyvinylpyrrolidone, hydroxypropyl methylcellulose, polyethylene glycol, hydroxylpropyl cellulose, polyethylene oxide, cellulose acetate phthalate, polyvinyl acetate phthalate and mixtures thereof