Pharmaceutical tablet capable of liberating one or more drugs at

Details Pharmaceutical tablet capable of liberating one or more drugs at Pharmaceutical tablet capable of liberating one or more drugs at

1995-03-24

1998-04-14

Page, Thurman L.

Drug, bio-affecting and body treating compositions

Preparations characterized by special physical form

Tablets, lozenges, or pills

424468, 424479, 424480, 424481, 424482, A61K 922, A61K 924, A61K 934, A61K 936

Patent

active

057388741

DESCRIPTION:

BRIEF SUMMARY
This application is a 371 of PCT/EP93/02556 filed Sep. 21, 1993.


PRIOR ART

The development of innovative pharmaceutical forms for drugs administration to humans and animals has lately been a source for considerable research effort in pharmaceutical technology. One of the major innovations in this sector is the targeting of drugs release to a specific sire of treatment and/or the release of said drug at a programmed rate.
The applications thereof are of consequence not only to human and animal health but also to agriculture.
Very many are the pharmaceutical forms already developed and disclosed in patents, which are capable of releasing the drug at zero-order kinetics.
As well known to those skilled in the pharmaceutical art, this means that the pharmaceutical form liberates the drug at a constant rate and over a scheduled period of time. In particular, drug release may occur according to the following empirical relation constant depending on the diffusion coefficient in the matrix and n is a constant depending on polymeric chains swelling and relaxation rate in swelling front.
Examples of said pharmaceutical forms are amply documented, e.g. in "Novel drug delivery and its therapeutical application" by L. F. Prescott and W. S. Nimmo, J. Wiley, New York, 1989. Examples refer to pharmaceutical forms that may be administered by different routes, i.e. oral, transdermic, vaginal, and ocular.
Obviously, due to the great importance and wide utilization of oral drug administration, many and diverse embodiments are for gastroenteric administration.
Among the widely known and used embodiments the OROS system., disclosed in U.S. Pat. No. 4,160,020 (1979), should be cited.
A further achievement in the area is the pharmaceutical form disclosed in U.S. Pat. No. 4,839,177 (1989) and in the subsequent U.S. patent application Ser. No. 07/620,577 dated 3rd Dec., 1990 now abandoned. Said patents claim the preparation of pharmaceutical forms for oral administration capable of liberating a drug at a constant release rate, i.e. according to zero-order kinetics.
In particular, the aforesaid patents disclose and claim the preparation of a tablet which, in its simplest form, consists of a hydrophilic matrix containing a drug and suitable excipients allowing the sustained release of the drug.
The drug sustained release is brought about by gelable hydrophilic polymers, which swell by contact with water and/or aqueous fluids, giving a gelled layer wherefrom the drug is liberated according to Fick's type kinetics.
The pharmaceutical form claimed in the aforementioned patents is characterized by the matrix being partly coated with a drug-impermeable barrier consisting of a polymeric film insoluble in water or in an aqueous medium. Alternatively, said barrier consists of polymeric mixtures or granular masses with technological adjuvants, applied by compression (Italian patent application No. 22694/89). The barrier obtained is drug-impermeable for at least 4-8 hrs and, therefore, hinders drug dispensing from the coated surface.
Therefore, the hydrophilic drug is exclusively released from the free area, generally at a constant rate.
However, the prior art does not envisage the possibility of obtaining products capable of releasing one or more drugs at different rates or else of releasing two different drugs sequentially, i.e. releasing the second drug only after releasing the first drug, both being contained in the same pharmaceutical form.
Several treatments require a sequential administration of two drugs and, therefore, involve complex posologic schemes and scrupulous patient's compliance therewith. Obviously, since such compliance is hardly obtainable, the above requirements can often be met only by hospitalized patients, carefully controlled by physicians and paramedical specialists.
As well known, complex therapeutic schemes are reluctantly accepted and scarcely followed by cut-patients, the correct compliance with posologic schemes being inversely proportional to the treatment complexity and to the number of daily administrations

REFERENCES:
patent: 4160020 (1979-07-01), Ayer
patent: 4839177 (1989-06-01), Colombo et al.
patent: 5188840 (1993-02-01), Iida et al.
Pharmacopeial Forum, May-Jun. 1992, vol. 18, No. 3, pp. 3389-3394.

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