the key aspect of the present invention is to prepare multiple coat segments on the core using the coating technology and incorporate different drug components in some of the coats . the core region of the dosage form can be a drug particle or a conventional pharmaceutical dosage form such as a tablet , capsule , pill , bead or an implant . the core region can be prepared using commonly used excipients and employing a commonly used manufacturing process known to people working in the pharmaceutical field . the central idea of the invention is to load different drugs in the same dosage form using the coating technology developing a unit dosage form with multiple drugs . if the drug solution is coated directly on the core region , the solution will have tendency to penetrate into the matrix . the depth of penetration will depend upon the compositions of core region and / or the coating solution and the process . this may allow the interaction between the drug in the core and the drug in the coat . in order to avoid this , it is important to coat the core region with a dividing layer . the composition and thickness of the dividing layer will depend upon the desired function . if the function is merely the separation of drugs in the core matrix and the coat , a simple coating of sugar or a water - soluble polymer such as , hydroxypropyl methylcellulose may be sufficient . if one desires to have a controlled , slow or sustained release of the drug in the core matrix , a variety of pharmaceutically approved polymers can be used . for enteric coating , a different set of commonly known polymers is used . a large variety of polymers are available with different properties including film - forming nature , swelling , gel formation , water penetration etc . a drug to be coated on the core region can be dissolved or suspended in a suitable solvent system to produce the coating formulation . the drug to be coated on the core region , if charged , can be ion - paired with an oppositely charged excipient — either a small molecule or a polymer . the drug can also be covalently bound to the polymeric matrix to form a polymeric prodrug . the intention is to attain a desired drug release rate from the dosage form . the drug may be dissolved in an emulsion or in a number of commonly available surfactant systems . these surfactants in these systems would also help the release of drug from the dosage form and may aid drug absorption . it is important that the solvent can be evaporated easily during the coating operation using conventional system such as air or vacuum or fluid - bed drying . the amount of drug to be loaded can be varied based on the desired dose per unit . the dosage form can be coated with additional layers , a sequence of dividing layer and the drug coat . during the coating operation , a precaution must be taken not to overheat the product to maintain the stability of drugs in the matrix and in the initial coat . the order of incorporation of drugs in the core matrix and coats may be varied based on the desired release sequence and rates can be altered using the correct dividing coat . this provides a better control to the formulator to obtain a desired pharmacokinetic profile . it is possible that a drug is delivered in a controlled fashion from the core matrix and the same drug in the coat produces an immediate release . this may have a huge clinical significance . the drugs in the coating segments may be in the solution or suspension form . the particle size of the drug in the suspension form will control the release rate if the drug has low aqueous solubility . the advent of nanotechnology may help produce a coating solution containing drug as nanoparticles . one can use microparticles or macroparticles in the suspension resulting into different release rates from the same dosage form . in a system , core beads containing different drugs are coated with solutions containing different set of drugs . these beads are delivered in a capsule dosage form enabling to put together multiple drugs in the same dosage form . there could be many permutations and combinations of this kind of system and many types of polymeric solutions can be applied to achieve different release rates . with the development of technology , very small volumes of liquids can be delivered ( less than 100 μl ). in a system , tiny droplets of drug solutions / suspensions are applied on a tablet surface . the solution on the tablet is dried immediately with a jet of hot air . a polymer layer can be applied to the tablet surface prior to or upon the addition of drug solutions or both producing a combination drug dosage form . the coating technology is very important for potent drugs for two reasons . the amount of drug applied is limited in a coat . more importantly , the coat is applied in a solution / suspension form . thus , there is no dusting of drug and the manufacturing personnel will be less exposed to the potent drugs . the delivery systems described in this patent are intended for oral , nasal , pulmonary , and implantable routes of administration .
the present invention claims the usage of coating technology to produce multi - segmented pharmaceutical dosage forms for a combination drug therapy . the core matrix containing a drug is coated with drug containing solutions or suspensions . the separation of different drugs in the core and various coating segments prevents drug - drug interaction and improve drug stability , provide desired release rates for different drugs in the dosage form . the dosage form may release drugs in different parts of the gastrointestinal tract .