MANTROCEL HP 55, HPMCP
Hydroxypropylmethylcellulosephthalat, Hypromellosephthalat EP

HPMCP (Hydroxypropyl Methylcellulose Phthalate), a cellulose derivative for enteric coating, has been demonstrated to be effective by many researchers and is widely used as an enteric coating agent by the pharmaceutical industry. HPMCP has been admitted into the U.S. National Formulary (US/NF). European Pharmacopeia (EP), and Japanese Pharmacopeia (JP). The chemical structure of HPMCP is a phthalic half ester of Hvdroxypropyl Methylcellulose, and the threshold pH value for rapid disintegration of Mantrocel HP 55 is around pH 5,5.

Mantrocel HP 55 may be dissolved in 80% (by wt) aqueous ethyl alcohol, acetone, 95% aqueous acetone,or a blend(1:1,by wt) of acetone and ethyl alcohol. It is not soluble in100% ethyl alcohol. When organic solvents are used, the environment and equipment used should be well ventilated and explosion-proof.

Solutions of Mantrocel HP 55 in a mixed solvent (like aqueous ethyl alcohol) may be prepared, at ambient temperature, by slow addition to the vortex of one of the solvents (ethyl alcohol) to disperse it and reduce lump formation, followed by addition of the other solvent (water) and agitation until solution is complete. lf pigments are used, they should be dispersed before the second solvent is added.

The solutions should have a sprayable viscosity of 100-300 cps (mPas) at about 5-11% solids and can include, optionally, plasticizers, pigments or surfactants. Plasticizers such as triethyl citrate, propylene glycol, polyethylene glycols, lipids, monoglycerides etc. may be used at 5-15% (on HPMCP dry wt) to produce more flexible films. Aluminum lakes, titanium dioxide or iron oxides may be used as pigments; titanium dioxide or talc may be used as opacity agents to achieve white or pale colors. High levels of pigmenting or opacity agents (usually10% or higher, on HPMCP wt) could affect the film properties (reduction of flexibility, strength or gastroresistence) and should be taken into account to determine the optimum enteric coating level.

Substrates may be spray-coated employing a side-vented pan or a fluidized bed system with top, bottom or tangential spray nozzles, under adequately controlled conditions of inlet/outlet air temperature, air supply rate, coating solution (% solids, temperature, flow rate), atomization pressure, pan load, pan speed and drying time to ensure optimum results. These parameters may vary greatly among specific applications depending on the pan size and configuration, substrate formulation, substrate load, substrate size/geometry, substrate heat or moisture sensitivity, ambient relative humidity, etc. Conventional pans may be used after careful experimentation to determine optimum application parameters and coating levels.

A typical coating application could be performed in a 48-in. side-vented pan with multiple spray nozzles and a load of 120-150 kg of large-size (15-mm) tablets. The inlet air temperature may be around 35-45° C (95-113° F). The pan speed may be 5-10 rpm. The amount of coating applied would depend on coating formulation and the tablet surface area and can start from 7-8% (on substrate wt). Adaptation of application parameters to specific substrates, equipment/conditions is recommended.