| 摘要 |
N-(3-dimethyl aminopropyl)-methacrylamide is copolymerized with methyl methacrylate in solution in ethyl acetate or chloroform using azodiisobutyronitrile as initiator. The copolymer is also prepared in emulsion by polymerizing the hydrochloride salt of the above-mentioned amide monomer, together with methyl methacrylate, in water containing a paraffin sulphonate and ammonium persulphate; the product is treated with NaOH to convert the polymer from salt form to free-base form. The copolymer is used in preparing enteric-type medicaments for ruminants (see Division A5).ALSO:Medicaments suitable for oral administration to ruminants and which are insoluble in the rumen but soluble in the abomasum, comprise a pharmaceutically active material coated with or embedded in a protective material which is acid soluble but alkaline resistant, the protective material being essentially composed of a copolymer of a substituted acrylamide of the formula CH2=CR-CO-NH(CH2)n-NR1R11 where R is H or C1-C4 alkyl, R1 and R11 are the same or different C1-C4 alkyl and n is 2, 3 or 4. The acrylamide compound may be copolymerised with, for example, styrene, methylstyrene, vinyl acetate or propionate, ethyl or n-butyl acrylate, acrylonitrile or, preferably, methyl methacrylate. 2,2/sv-dihydroxy-3,3/sv-dinitro -5,5/sv-dichlorodiphenyl is specified as active material. |
