An oral formulation of tadalafil and its preparation method
By designing an oral formulation of tadalafil containing a tablet core and a gastric coating layer, the problem of tadalafil's easy decomposition in gastric juice was solved, achieving rapid dissolution and stable drug release in the intestine, thus improving bioavailability and efficacy.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- ANHUI BIOCHEM BIO PHARMA
- Filing Date
- 2023-07-24
- Publication Date
- 2026-06-30
AI Technical Summary
Tadalafil is easily broken down in gastric juice, resulting in low bioavailability and instability, which is difficult to effectively solve with existing technologies.
The oral formulation of tadalafil uses a core and a gastric coating. The core consists of microcapsules, a core filler, and a core lubricant. The microcapsules are protected by enteric and gastric coatings to ensure that they do not decompose in gastric juice and dissolve rapidly in the intestine.
It improves the bioavailability of tadalafil, avoids decomposition in gastric juice, ensures rapid dissolution of the drug in the intestine, improves efficacy, and has good product quality stability.
Smart Images
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Abstract
Description
Technical Field
[0001] This invention relates to the field of pharmaceutical technology, and in particular to an oral formulation of tadalafil and its preparation method. Background Technology
[0002] Tadalafil, developed by Eli Lilly and Company, is used to treat erectile dysfunction (ED), pulmonary hypertension, and benign prostatic hyperplasia. Tadalafil tablets are marketed under the brand name Cialis. The US FDA approved it in 2003, and it was approved for the Chinese market by the State Food and Drug Administration in December 2004. Tadalafil is a long-acting phosphodiesterase type 5 (PDE-5) inhibitor. Its Chinese chemical name is (6R,12aR)-2,3,6,7,12,12a-hexahydro-2-methyl-6-[3,4-methylenedioxyphenyl]pyrazino[1,2,:1,6]pyridino[3,4-b]indole-1,4-dione, with the following structural formula:
[0003]
[0004] Tadalafil requires sexual stimulation to be effective in treating erectile dysfunction in men. Sexual stimulation leads to the local release of nitric oxide, which inhibits PDE5, increasing cGMP levels in the corpora cavernosa of the penis. This causes relaxation of smooth muscle, allowing blood to flow into the penile tissue and resulting in an erection. For most patients, it is taken as needed, with a recommended starting dose of 10 mg, taken before sexual activity.
[0005] Tadalafil is readily soluble in dimethyl sulfoxide and N,N-dimethylformamide, slightly soluble in dichloromethane, sparingly soluble in acetonitrile, and practically insoluble in water. Because tadalafil is a poorly soluble drug, its bioavailability is relatively low, requiring relatively large doses and potentially causing adverse reactions. Furthermore, tadalafil is unstable and easily degrades in acidic environments. When taking tadalafil-related medications, it is destroyed in gastric juices, affecting its efficacy. Summary of the Invention
[0006] In view of this, the present invention aims to provide an oral formulation of tadalafil and a method for preparing the same, which can avoid the decomposition of the active ingredient tadalafil in gastric juice and can improve drug dissolution and bioavailability.
[0007] To achieve the above objectives, the technical solution of the present invention is implemented as follows:
[0008] On one hand, the present invention proposes an oral formulation of tadalafil, which comprises a tablet core and a gastric coating layer.
[0009] The core comprises the following components in parts by weight: 200 parts micro pellets, 60-130 parts core filler, and 6-40 parts core lubricant;
[0010] The microspheres include an inner core and an enteric coating;
[0011] The core comprises the following raw materials in parts by weight: 20 parts tadalafil, 15-30 parts nonionic surfactant, 30-40 parts core disintegrant and 80-130 parts core filler.
[0012] Furthermore, the core filler is selected from at least one of microcrystalline cellulose, lactose, and starch.
[0013] Furthermore, the core lubricant is selected from at least one of micronized silica gel, talc, and magnesium stearate.
[0014] Furthermore, the nonionic surfactant is at least one of gum arabic, glycerin, and poloxamer.
[0015] Furthermore, the tablet core disintegrant is selected from at least one of sodium carboxymethyl starch, croscarmellose sodium, and low-substituted hydroxypropyl cellulose.
[0016] Furthermore, the core filler is selected from at least one of microcrystalline cellulose, lactose, and starch.
[0017] On the other hand, the present invention also proposes a method for preparing an oral formulation of tadalafil, the method comprising the following steps:
[0018] S1. Weigh each component according to the prescription amount, and pass the solid components through a 60-80 mesh sieve respectively;
[0019] S2. Tadalafil, nonionic surfactant, core disintegrant and water are homogenized and emulsified to obtain tadalafil suspension; the tadalafil suspension is mixed with core filler in the form of spray and then added to a granulator for granulation to obtain core.
[0020] S3. The inner core is coated once using enteric coating to obtain microspheres;
[0021] S4. The micro-pellets, tablet core filler, and tablet core lubricant are mixed and then compressed into tablets to obtain tablet cores;
[0022] S5. The tablet core is coated a second time using a gastric coating layer to obtain an oral tadalafil formulation.
[0023] Furthermore, in step S3, when performing a single coating using enteric coating, the coating weight is increased by 2-5% to obtain microspheres.
[0024] Furthermore, in step S5, when performing secondary coating using the gastric coating layer, the coating weight is increased by 2-3% to obtain the oral tadalafil formulation.
[0025] Compared with existing technologies, the oral tadalafil formulation and its preparation method described in this invention have the following advantages:
[0026] (1) The oral tadalafil preparation prepared by this invention exhibits less drug dissolution under simulated gastric acid conditions, effectively avoiding the degradation of tadalafil in the stomach and thus preventing a decrease in efficacy, and overcoming the problem of instability of raw materials under acidic conditions. Under simulated intestinal environment conditions, the oral tadalafil preparation can dissolve rapidly and with good dissolution effect, allowing the drug to exert its effect quickly.
[0027] (2) In the same batch, the contents of multiple tablets of the oral tadalafil preparation prepared by the present invention are not much different, the product quality is controllable, and the stability is good. Detailed Implementation
[0028] The present invention will be further described below with reference to specific embodiments. First, it should be noted that the data in the following experimental examples were obtained by the inventors through numerous experiments. Due to space limitations, only a portion of these data is shown in the specification, and those skilled in the art can understand and implement the present invention based on this data. These embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, it should be understood that after reading the contents of this invention, those skilled in the art can make various modifications or alterations to the invention, and these modifications or alterations also fall within the scope of protection of this application.
[0029] Example 1
[0030] Weigh out the prescribed amounts of each component and pass the solid components through a 60-80 mesh sieve.
[0031] 25g of gum arabic was dispersed in 300g of water, and 20g of tadalafil and 35g of sodium carboxymethyl starch were added. The mixture was homogenized and emulsified at 15000rpm for 10min to obtain a tadalafil suspension. The tadalafil suspension was sprayed onto 120g of microcrystalline cellulose in the form of a spray, and then added to a granulator for granulation, drying, and sizing to obtain a granular core.
[0032] Enteric-coated oba was prepared into a coating solution. Using fluidized bed technology, the coating solution was evenly sprayed onto the inner core for the first coating. Microspheres were obtained when the coating weight increased by 2-5%.
[0033] Weigh out 200g of microcapsules, 130g of lactose and 20g of micro-powdered silica gel, mix them evenly, and then compress them into tablets to obtain tablet cores.
[0034] A gastrointestinal film-coated hydroxypropyl methylcellulose was prepared into a coating solution and sprayed evenly onto the tablet core for a second coating until the coating weight increased by 2-3%, yielding 1000 tablets of tadalafil oral formulation.
[0035] Example 2
[0036] Weigh out the prescribed amounts of each component and pass the solid components through a 60-80 mesh sieve.
[0037] 25g of gum arabic was dispersed in 300g of water, and 20g of tadalafil and 35g of croscarmellose sodium were added. The mixture was homogenized and emulsified at 15000rpm for 10min to obtain a tadalafil suspension. The tadalafil suspension was sprayed onto 120g of microcrystalline cellulose in the form of a spray, and then added to a granulator for granulation, drying, and sizing to obtain a granular core.
[0038] Enteric-coated oba was prepared into a coating solution. Using fluidized bed technology, the coating solution was evenly sprayed onto the inner core for the first coating. Microspheres were obtained when the coating weight increased by 2-5%.
[0039] Weigh out 200g of microcapsules, 130g of lactose and 20g of micro-powdered silica gel, mix them evenly, and then compress them into tablets to obtain tablet cores.
[0040] A gastrointestinal film-coated hydroxypropyl methylcellulose was prepared into a coating solution and sprayed evenly onto the tablet core for a second coating until the coating weight increased by 2-3%, yielding 1000 tablets of tadalafil oral formulation.
[0041] Example 3
[0042] Weigh out the prescribed amounts of each component and pass the solid components through a 60-80 mesh sieve.
[0043] 25g of gum arabic was dispersed in 300g of water, and 20g of tadalafil and 35g of low-substituted hydroxypropyl cellulose were added. The mixture was homogenized and emulsified at 15000rpm for 10min to obtain a tadalafil suspension. The tadalafil suspension was sprayed onto 120g of microcrystalline cellulose in the form of a spray, and then added to a granulator for granulation, drying, and sizing to obtain a granular core.
[0044] Enteric-coated oba was prepared into a coating solution. Using fluidized bed technology, the coating solution was evenly sprayed onto the inner core for the first coating. Microspheres were obtained when the coating weight increased by 2-5%.
[0045] Weigh out 200g of microcapsules, 130g of lactose and 20g of micro-powdered silica gel, mix them evenly, and then compress them into tablets to obtain tablet cores.
[0046] A gastrointestinal film-coated hydroxypropyl methylcellulose was prepared into a coating solution and sprayed evenly onto the tablet core for a second coating until the coating weight increased by 2-3%, yielding 1000 tablets of tadalafil oral formulation.
[0047] Example 4
[0048] Weigh out the prescribed amounts of each component and pass the solid components through a 60-80 mesh sieve.
[0049] 30g of poloxamer was dispersed in 350g of water, and 20g of tadalafil and 40g of low-substituted hydroxypropyl cellulose were added. The mixture was homogenized and emulsified at 15000rpm for 15min to obtain a tadalafil suspension. The tadalafil suspension was sprayed onto 110g of starch in the form of a spray, and then added to a granulator for granulation, drying, and sizing to obtain a granular core.
[0050] Enteric-coated cellulose acetate phthalate was formulated into a coating solution. The coating solution was then uniformly sprayed onto the inner core using fluidized bed technology for the first coating. Microspheres were obtained when the coating weight increased by 2-5%.
[0051] Weigh out 200g of microcapsules, 110g of microcrystalline cellulose and 40g of magnesium stearate, mix them evenly and compress them into tablets to obtain tablet cores.
[0052] A gastrointestinal film-coating polyvinylpyrrolidone was prepared into a coating solution and sprayed evenly onto the tablet core for a second coating until the coating weight increased by 2-3%, yielding 1000 tablets of tadalafil oral formulation.
[0053] Example 5
[0054] Weigh out the prescribed amounts of each component and pass the solid components through a 60-80 mesh sieve.
[0055] 30g of poloxamer was dispersed in 350g of water, and 20g of tadalafil and 40g of low-substituted hydroxypropyl cellulose were added. The mixture was homogenized and emulsified at 15000rpm for 15min to obtain a tadalafil suspension. The tadalafil suspension was sprayed onto 110g of lactose in the form of a spray, and then added to a granulator for granulation, drying, and sizing to obtain a granular core.
[0056] Enteric-coated cellulose acetate phthalate was formulated into a coating solution. The coating solution was then uniformly sprayed onto the inner core using fluidized bed technology for the first coating. Microspheres were obtained when the coating weight increased by 2-5%.
[0057] Weigh out 200g of microcapsules, 110g of lactose and 40g of magnesium stearate, mix them evenly, and then compress them into tablets to obtain tablet cores.
[0058] A gastrointestinal film-coating polyvinylpyrrolidone was prepared into a coating solution and sprayed evenly onto the tablet core for a second coating until the coating weight increased by 2-3%, yielding 1000 tablets of tadalafil oral formulation.
[0059] Example 6
[0060] Weigh out the prescribed amounts of each component and pass the solid components through a 60-80 mesh sieve.
[0061] 30g of poloxamer was dispersed in 350g of water, and 20g of tadalafil and 40g of low-substituted hydroxypropyl cellulose were added. The mixture was homogenized and emulsified at 15000rpm for 15min to obtain a tadalafil suspension. The tadalafil suspension was sprayed onto 110g of microcrystalline cellulose in the form of a spray, and then added to a granulator for granulation, drying, and sizing to obtain a granular core.
[0062] Enteric-coated cellulose acetate phthalate was formulated into a coating solution. The coating solution was then uniformly sprayed onto the inner core using fluidized bed technology for the first coating. Microspheres were obtained when the coating weight increased by 2-5%.
[0063] Weigh out 200g of micro-pellets, 110g of starch and 40g of magnesium stearate, mix them evenly and compress them into tablets to obtain tablet cores.
[0064] A gastrointestinal film-coating polyvinylpyrrolidone was prepared into a coating solution and sprayed evenly onto the tablet core for a second coating until the coating weight increased by 2-3%, yielding 1000 tablets of tadalafil oral formulation.
[0065] When coating tablet cores with a gastrointestinal coating agent, the applicant found that a small amount of powder would detach when the gastrointestinal coating layer wrapped the tablet core, and the secondary coating could not completely adhere to the tablet core, resulting in a certain scrap rate. The possible reason is that the enteric coating on the microcapsules is relatively smooth, causing the gastrointestinal coating to not completely cover the core. Therefore, the applicant further improved the tadalafil process of this invention and found that when both the inner core filler and the tablet core filler are starch, the gastrointestinal coating can completely adhere to the surface of the tablet core, improving the yield of the oral tadalafil formulation. It is speculated that the starch used has a certain degree of roughness, which can improve the problem of incomplete gastrointestinal coating caused by the smoothness of the enteric coating. Moreover, starch has good adhesive properties, which helps to further improve the adhesion of the gastrointestinal coating to the surface of the tablet core. Specific preparation methods are shown in Examples 7-8.
[0066] Example 7
[0067] Weigh out the prescribed amounts of each component and pass the solid components through a 60-80 mesh sieve.
[0068] 20g of glycerol was dispersed in 300g of water, and 20g of tadalafil and 30g of low-substituted hydroxypropyl cellulose were added. The mixture was homogenized and emulsified at 15000rpm for 12min to obtain a tadalafil suspension. The tadalafil suspension was sprayed onto 130g of starch in the form of a spray, and then added to a granulator for granulation, drying, and sizing to obtain a granular core.
[0069] Enteric-coated cellulose acetate phthalate was formulated into a coating solution. The coating solution was then uniformly sprayed onto the inner core using fluidized bed technology for the first coating. Microspheres were obtained when the coating weight increased by 2-5%.
[0070] Weigh out 200g of micro-pellets, 120g of starch and 30g of talc, mix them evenly, and then compress them into tablets to obtain tablet cores.
[0071] A gastrointestinal film-coating polyvinylpyrrolidone was prepared into a coating solution and sprayed evenly onto the tablet core for a second coating until the coating weight increased by 2-3%, yielding 1000 tablets of tadalafil oral formulation.
[0072] Example 8
[0073] Weigh out the prescribed amounts of each component and pass the solid components through a 60-80 mesh sieve.
[0074] 30g of poloxamer was dispersed in 350g of water, and 20g of tadalafil and 40g of low-substituted hydroxypropyl cellulose were added. The mixture was homogenized and emulsified at 15000rpm for 15min to obtain a tadalafil suspension. The tadalafil suspension was sprayed onto 110g of starch in the form of a spray, and then added to a granulator for granulation, drying, and sizing to obtain a granular core.
[0075] Enteric-coated cellulose acetate phthalate was formulated into a coating solution. The coating solution was then uniformly sprayed onto the inner core using fluidized bed technology for the first coating. Microspheres were obtained when the coating weight increased by 2-5%.
[0076] Weigh out 200g of micro-pellets, 110g of starch and 40g of magnesium stearate, mix them evenly and compress them into tablets to obtain tablet cores.
[0077] A gastrointestinal film-coating polyvinylpyrrolidone was prepared into a coating solution and sprayed evenly onto the tablet core for a second coating until the coating weight increased by 2-3%, yielding 1000 tablets of tadalafil oral formulation.
[0078] Comparative Example 1
[0079] Tadalafil enteric-coated tablets were prepared using the method described in Example 1 of CN109528675A, with Opadry enteric coating used for coating and a coating weight gain of 5%.
[0080] Content determination
[0081] Five tablets each of the tadalafil oral formulations prepared in Examples 1-8 and the tadalafil enteric-coated tablets prepared in Comparative Example 1 from the same batch were used for content determination. The test samples were added to volumetric flasks, and diluent was added to half the volume of each flask. The mixture was shaken for 15 minutes to disperse the test samples. The volume was then adjusted to the mark with diluent, and the mixture was shaken again. After the sample solution was completely dissolved, the stock solution was diluted to 0.25 mg / mL, and the solution was filtered to obtain the test sample solution. A reference solution was then prepared, and the content was determined using high-performance liquid chromatography (HPLC). The specific results are shown in Table 1.
[0082] Table 1
[0083]
[0084]
[0085] As shown in Table 1, within the same batch, the content of multiple tablets of the tadalafil oral formulations prepared in Examples 1-8 of this invention is not significantly different. For manufacturers, this is beneficial for controlling drug quality, ensuring uniform content in oral formulations produced within the same batch, and showing no significant difference in drug content between tablets. For users, it allows for better dosage control and maximizes the effectiveness of the tadalafil oral formulation. In contrast, the tadalafil tablets prepared in Comparative Example 1 within the same batch showed significant differences in content, with some tablets containing as much as 99.1% and others containing only 92.5%, which is detrimental to drug quality control and may affect efficacy.
[0086] The tadalafil oral formulation prepared using the method of this invention is first prepared into a granular core, and then compressed into tablets, thus combining the advantages of both granules and tablets. After oral administration, it facilitates uniform distribution in the user's intestines and improves absorption, avoiding excessively high local drug concentrations that could irritate the body. Furthermore, compared to Comparative Example 1, this invention mixes tadalafil with some excipients, prepares a granular core, and then performs enteric coating to obtain microspheres. These microspheres are less prone to breakage during tableting. In contrast, Comparative Example 1 directly granulates and compresses tadalafil with excipients, which can lead to breakage during tableting. This not only affects the yield but also causes damage to the enteric coating due to poor formability, resulting in the sudden release of tadalafil in gastric juice before reaching the intestines. Tadalafil is then destroyed in the stomach, reducing its efficacy.
[0087] Comparative Example 2
[0088] Weigh out the prescribed amounts of each component and pass the solid components through a 60-80 mesh sieve.
[0089] 20g of glycerol was dispersed in 300g of water, and 20g of tadalafil was added. The mixture was homogenized and emulsified at 15000rpm for 12min to obtain a tadalafil suspension. 100g of mannitol was placed in a fluidized bed reactor and heated with hot air. After the material temperature reached above 50℃, the tadalafil suspension was sprayed onto the mannitol surface. After spraying, the mixture was dried until the exhaust temperature reached 60℃. Then, 30g of low-substituted hydroxypropyl cellulose and 130g of starch were added, and the mixture was placed in a granulator for granulation, drying, and sizing to obtain a granular core.
[0090] Enteric-coated cellulose acetate phthalate was formulated into a coating solution. The coating solution was then uniformly sprayed onto the inner core using fluidized bed technology for the first coating. Microspheres were obtained when the coating weight increased by 2-5%.
[0091] Weigh out 200g of micro-pellets, 120g of starch and 30g of talc, mix them evenly, and then compress them into tablets to obtain tablet cores.
[0092] A gastrointestinal film-coating polyvinylpyrrolidone was prepared into a coating solution and sprayed evenly onto the tablet core for a second coating until the coating weight increased by 2-3%, yielding 1000 tablets of tadalafil oral formulation.
[0093] Dissolution test
[0094] The tadalafil oral formulations prepared in Examples 1-8, the tadalafil tablets prepared in Comparative Example 1, and the tadalafil oral formulation prepared in Comparative Example 2 were prepared according to the General Rules of Part IV of the 2015 Edition of the Chinese Pharmacopoeia. <0931> Dissolution testing was conducted according to the "Method 1, Paddle Method" under the "Enteric-coated Preparations" section of the Dissolution and Release Determination Method, using high-performance liquid chromatography (HPLC) at 225 nm. The dissolution medium was 0.1 mol / L hydrochloric acid solution (0.3% sodium dodecyl sulfate) to simulate the drug release environment in gastric juice. Dissolution was also determined according to the Japanese Pharmacopoeia Dissolution Test Method, using a pH 6.0 citric acid-sodium citrate medium to simulate the intestinal environment. Specific results are shown in Table 2.
[0095] Table 2
[0096]
[0097]
[0098] Table 2 shows that the tadalafil oral formulations prepared in Examples 1-8 and the tadalafil tablets prepared in Comparative Examples 1-2 exhibited less drug dissolution under simulated gastric acid conditions. This effectively prevented tadalafil from being destroyed in the stomach, thus avoiding a decrease in efficacy and overcoming the problem of instability of the raw materials under acidic conditions. Under simulated intestinal environment conditions, the tadalafil oral formulations prepared in Examples 1-8 were rapidly dissolved, with a cumulative dissolution rate of 88.3-92.8% at 10 minutes and 98.0-99.9% at 15 minutes. When users take tadalafil orally to improve erectile dysfunction, the drug can exert its effect quickly without waiting for a long time. Users also do not need to take the tadalafil oral formulation a long time in advance. Although the tadalafil tablets in Comparative Example 1 also dissolved rapidly under simulated intestinal environment conditions, the dissolution effect was not as good as that in Examples 1-8. The tadalafil oral formulation prepared in Comparative Example 2 had a different order of addition of the core disintegrant, resulting in a less effective dissolution than that in Examples 1-8.
[0099] By comparing the dissolution effects of Examples 1-8, the applicant found that when low-substituted hydroxypropyl cellulose was used as the disintegrant, the dissolution effect was better than that of other disintegrants. The applicant hypothesizes that in improving the dissolution of tadalafil, a nonionic surfactant is used to increase the hydrophilicity of the poorly soluble tadalafil and disperse it into fine particles. The tadalafil and nonionic surfactant further disperse the tadalafil particles under the action of homogenization and emulsification. Furthermore, since a disintegrant is added during homogenization and emulsification, the homogenized disintegrant also forms fine particles. The fine particles of tadalafil and the fine particles of the disintegrant are in full contact, which not only prevents the aggregation of tadalafil particles but also better exerts the disintegrant effect, thus improving the dissolution of tadalafil. Compared to other disintegrants, low-substituted hydroxypropyl cellulose has a relatively rough structure, which facilitates interlocking with the fine particles of low-substituted hydroxypropyl cellulose, making the overall structure more porous and increasing the wetting rate of poorly soluble drugs, thereby enabling rapid release of tadalafil.
[0100] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.
Claims
1. A method for preparing an oral formulation of tadalafil, characterized by, The oral tadalafil formulation comprises a tablet core and a gastric coating. The tablet core comprises the following components in parts by weight: 200 parts microcapsules, 120 parts starch, and 30 parts talc; the microcapsules comprise an inner core and an enteric coating; the inner core comprises the following raw materials in parts by weight: 20 parts glycerol, 20 parts tadalafil, 30 parts low-substituted hydroxypropyl cellulose, and 130 parts starch; or, The core comprises the following components in parts by weight: 200 parts microcapsules, 110 parts starch and 40 parts magnesium stearate; the microcapsules comprise an inner core and an enteric coating; the inner core comprises the following raw materials in parts by weight: 30 parts poloxamer, 20 parts tadalafil, 40 parts low-substituted hydroxypropyl cellulose and 110 parts starch. The method for preparing the oral tadalafil formulation includes the following steps: S1. Weigh each component of the prescription and pass the solid components through a 60-80 mesh sieve respectively; S2. Tadalafil, glycerol or poloxamer, low-substituted hydroxypropyl cellulose and water are homogenized and emulsified to obtain a tadalafil suspension; the tadalafil suspension is mixed with starch in a spray form and then added to a granulator for granulation to obtain the inner core; S3. After coating the inner core once with enteric coating, the coating weight increases by 2-5% to obtain micro pellets; S4. The micro-pellets, starch, talc or magnesium stearate are mixed and then compressed into tablets to obtain tablet cores; S5. The tablet core is coated a second time using a gastric coating layer to obtain an oral tadalafil formulation.
2. The method for preparing the oral tadalafil formulation according to claim 1, characterized in that, In step S5, when performing secondary coating using the gastric coating layer, the coating weight is increased by 2-3% to obtain the oral tadalafil formulation.