Coating agent for pharmaceutical solid preparation, pharmaceutical film formulation, and coated pharmaceutical solid preparation

A pharmaceutical film formulation comprising a polyethylene glycol having an average molecular weight of 950 to 25,000 and a swelling clay, wherein a mass ratio of said polyethylene glycol and said swelling clay is 2:8 to 6:4 and

• water vapor permeability at a room temperature of 40° C. and a relative humidity of 75% is less than 1.0×10−4 g·mm/cm2·24 hr·atm.

A coated pharmaceutical solid preparation comprising a coating layer,

• said coating layer comprising a polyethylene glycol having an average molecular weight of 950 to 25,000 and a swelling day,
• in which coating layer a mass ratio of said polyethylene glycol and said swelling clay is 2:8 to 5:4 and
• water vapor permeability at a room temperature of 40° C. and a relative humidity of 75% is less than 1.0×10−4 g·mm/cm2·24 hr·atm.