Transdermal Absorptive drug formulation

Abstract: A transdermal absorptive drug formulation containing 3-isobutyryl-2-isopropylpyrazolo[1,5-a]pyridine as active ingredient effective for bronchial asthma and cerebrovascular disorder is provided. The formulation affords excellent sustained releasing and long acting characteristics with substantially reduced side-effects such as nausea and vomiting.

Description: This invention relates to a transdermal absorptive drug formulation containing 3-isobutyryl-2-isopropylpyrazolo[1,5-a]pyridine (hereinafter referred to as ibudilast according to its international nonproprietary name) which is a drug for the treatment of bronchial asthma and cerebrovascular disorders. Ibudilast was developed by Irikura et al. (Japanese Patent Publication Sho 52-29318, corresponding to U.S. Patent 3,850,941, U.K. Patent 1,378,375 and so on) and has been proved by clinical tests to be useful for preventing and treating bronchial asthma. Its utility as a drug for the treatment of cerebrovascular disorders has also been reported. When ibudilast is orally administered to humans in a dosage form having no sustained release, a rapid absorption from the gastrointestinal tract will produce a steep rise of the serum concentration resulting in side-effects such as nausea and vomiting. Therefore, as far as oral preparations are concerned, sustained release capsules, tablets and the like are proposed for the compound (Japanese Laid-Open Patent Application Sho 60-193913, corresponding to EP-A-0 156 243). Also the compound has been successfully formulated for rectal administration because of using bases for preventing a rapid increase in the serum concentration (Japanese Laid-Open Patent Application Sho 60-193913). Since bronchial asthma and cerebrovascular disorders are often found among children and senile patients, respectively, it is desired to develop a dosage form of ibudilast which can be more easily administered. Thus, the technical problem underlying the present invention is to provide a drug formulation containing ibudilast as effective constituent with reduced side-effects, such as vomiting and the like. The solution of this technical problem is evident from the claims and the description. The invention is based on the finding that ibudilast exhibits excellent transdermal absorption. The transdermal absorptive drug formulation of the present invention may be utilized preferably in the form of an ointment, a cream or a plaster. These dosage forms assure easy administration and excellent sustained release or long acting properties. As for the bases for ointments or cream, a water-in-oil type emulsion base will be employed. The ointment of ibudilast may be prepared by the use of a water-in-oil type emulsion base having excellent absorptive and long acting properties. For preparing the ointment, 1 to 10 wt% of ibudilast is blended with the ointment base, if necessary heated to obtain a homogeneous mixture and then solidified to obtain said drug. The plaster is applied in the dosage forms of patch, cataplasm, transdermal patch, adhesive tape and the like. For preparing the plaster of ibudilast, it is preferable that an ointment base is blended with ibudilast or applied on a cloth to be formed together with other constituent materials such as substrates, liners, backing materials. The ibudilast concentration in the plaster ranges from 0.5 to 10 mg/cm², preferably 1 to 5 mg/cm². For the purpose of controlling the drug release from the plaster, a method may be employed wherein a drug releasing layer is formed between the drug storing layer and the adhesive mass as well as the ingredients of the plaster are modified. Thus obtained transdermal absorptive drug formulation of ibudilast according to this invention, excellent in its absorption property, may be employed under any condition of a disease such as that in asthma fit or the like and can be conveniently applied, with remarkably reduced side-effects such as nausea, vomiting and the like. Also, the dosage form itself can freely control the dose amount, and as plaster, the drug has many advantages such as prevention of the contamination of clothes by the ointment base or the drug. Detailed Description of the Preferred Embodiments: Example: The following examples 4 and 7 illustrate embodiments of this invention. Examples 1 to 3, 5 and 6 represent comparative examples. Example 1: After mixing 47.5 g of liquid paraffin with 47.5 g of white vaseline, the mixture was heated to about 60°C to be dissolved. 5 g of ibudilast was added to the solution and dissolved. Then the resultant solution was cooled to room temperature under stirring to produce an oily ointment. Example 2: 47.5 g of macrogol-4000 and 47.5 g of macrogol-400 were mixed together homogeneously, then 5 g of ibudilast was added to the mixture and mixed to produce a macrogol ointment. Example 3: 23.75 g of white vaseline, 19 g of stearyl alcohol, 3.8 g of polyoxyethylene hydrogenated castor oil-60, 0.9 g of glycerol monostearate and 5 g of ibudilast were mixed together, and the mixture was kept at 75°C under stirring. Separately, 0.095 g of methyl p-hydroxybenzoate and 0.095 g of propyl p-hydroxybenzoate were dissolved into 11.4 g of propylene glycol, and 360 g of purified water was added to the solution, then the mixture was heated to 75°C. Then this solution was added to the former solution and stirred to form a latex. The latex was cooled and mixed until it became solidified to produce a hydrophilic ointment. Example 4: Taking 380 g of white vaseline, 95 g of cetanol, 47.5 g of mustard beeswax, 47.5 g of sorbitan sesquioleate, 4.75 g of macrogol and 50 g of ibudilast, they were melted together by heating and kept at 75°C. To this solution were added a previously prepared solution which was produced by adding 0.95 g of methyl p-hydroxybenzoate and 0.95 g of butyl p-hydroxybenzoate into about 374 ml of purified water and heated the mixture at 80°C. The resultant mixture was blended to make a latex, then it was cooled and mixed until it became solidified to form an absorptive ointment. Example 5: 25 g of stearyl alcohol, 5 g of stearic acid, 5 g of polyethylene glycol-6000, and 5 g of 1,2,6-hexanetriol, were dissolved together by heating at 80° to 85°C, then into which 5.3 g of ibudilast was added and mixed. To this solution was added 60 g of separately prepared propylene glycol warmed at 90°C and stirred. Then, the resultant mixture was stirred and cooled until it became solidified to obtain a FAPG ointment. Example 6: Into 20 g of purified water, 1 g of Carboball-934 was added and was allowed to be swollen, to which was added a solution made by mixing 12 g of propylene glycol, 30 g of ethanol, 2 g of di-isopropyl adipate and 5.3 g of ibudilast. Then was added to the mixture a solution which was independently prepared by dissolving 1.1 g of di-isopropanolamine into 10 ml of purified water. And another 23.9 g of purified water was added to the solution and stirred homogeneously to form a gell ointment. Example 7: 5 g of ibudilast was dissolved into a 100 ml of silicone adhesive mass solution. The resulting liquid was applied to a non-rigid PVC sheet and dried at 60°C for 30 min. to produce a plaster preparation. Test 1: Transdermal absorptive drug formulations which were prepared according to the foregoing examples were measured to determine transdermal absorption ratios. The test procedures were as follows: after shaving the back of about 3 kg of an albino rabbit with a hair-cutter, each of the ointments prepared according to the methods shown in the foregoing examples was applied in an amount of 1.5 g onto said shaved skin surface, and after the elapse of 5 hours after the application of ointment, it was recovered to measure the residual amount of ibudilast and the absorption ratio thereof was calculated. Table 1 shows the results. Absorption Ratios of Ibudilast of Ointments Example Type of Ointment Absorption Ratio (%) 1 Oily Ointment 17.3 2 Macrogol Ointment 3.5 4 Absorptive Ointment 42.6 5 FAPG Ointment 13.1 Transdermal absorption of ibudilast was recognized in any of the ointments. In particular, the absorptive ointment had a high value of transdermal absorption ratio. Test 2: Measurement was conducted on the serum concentration due to the use of the transdermal absorptive ointments prepared according to the foregoing examples. This test was conducted as follows: about 3 kg of an albino rabbit prepared, the hair of its back was shaved with a hair-cutter, and an ointment according to the example 4 was applied in an amount of 1.6 g (per one rabbit) to the rabbit; and after a predetermined time, the blood samples were prepared, from which serum was separated and subjected to high performance liquid chromatography to measure the serum concentrations of ibudilast. Table 2 shows the results. The serum concentration of ibudilast began to show a high value after the elapse of one hour after the application of the ointment and high values were kept for a long time, indicating its usefulness as a transdermal absorptive drug formulation. As stated above, the transdermal absorptive drug formulations according to this invention abate side-effects such as nausea, vomiting and the like caused when the drug is orally administered and have effects to keep a high concentration in the blood for a long time.

Claims: Claims for the following Contracting States : BE, CH, DE, FR, GB, IT, LI, NL, SE A transdermal absorptive drug formulation containing 3-isobutyryl-2-isopropylpyrazolo[1,5-a]pyridine as active ingredient, wherein the formulation is an ointment on a water- in-oil type emulsion base, or is a plaster. A transdermal absorptive drug formulation according to claim 1, wherein the transdermal absorptive drug formulation is in the form of an ointment. A transdermal absorptive drug formulation according to claim 1, wherein the transdermal absorptive drug formulation is in the form of a plaster. A transdermal absorptive drug formulation, according to claim 2 or claim 3, wherein the amount of 3-isobutyryl-2-isopropylpyrazolo[1,5-a]pyridine contained in said drug ranges from 1 to 10 wt%. Claims for the following Contracting State : ES A method for preparing a transdermal absorptive drug formulation containing 3-isobutyryl-2-isopropylpyrazolo[1,5-a]pyridine as an active ingredient by blending said active ingredient with an ointment base and formulating it to an ointment on a water-in-oil type emulsion base or to a plaster. The method according to claim 1 wherein the obtained transdermal absorptive drug formulation is in the form of an ointment. The method according to claim 1 wherein the obtained transdermal absorptive drug formulation is in the form of a plaster. The method according to claim 2 or claim 3 wherein the amount of 3-isobutyryl-2-isopropylpyrazolo[1,5-a]pyridine in said drug ranges from 1 to 10 wt%.

Inventors: IMAI JUN, KAMIJO SHINJI, KODAIRA HIROMICHI, IMAI, JUN, KAMIJO, SHINJI, KODAIRA, HIROMICHI
Applicants: KYORIN SEIYAKU KK, KYORIN SEIYAKU KABUSHIKI KAISHA
Application year: 1988
Main classification: A61L15
IPC codes: A61K9, A61K47, A61K31, A61P11