Corresponding author: Krum Kafedjiiski (
The present work was conducted with the aim to formulate and evaluate the immediate release of 1000 mg tablets containing Inosine Acedoben Dimepranol (
The active substance Inosine Acedoben Dimepranol (INN) (
The drug was developed by Newport Pharmaceuticals in the 1970s and distributed in more than 80 countries under the trademarks IsoprinosineTM, InmunovirTM and ViruxanTM (owned by Newport) for the treatment of viral infections.
According to the Summary of product characteristics of the product IsoprinosineTM 500 mg tablets (
Due to its potent immunomodulatory properties,
The active substance is a compound (complex) of inosine (1,9-dihydro-9-Dribofurasonyl-6H-purin-6-one) and a salt of 4-acetamidobenzoic acid with N, N dimethylamino-2-propanol in a molar ratio of 1: 3. It is a crystalline powder with a white to cream color and a characteristic odor, freely soluble in water, sparingly soluble in methanol, acetone, ethanol (
In the first publication (
Since in most indications of
The 1000 mg dose of the as the dosage form Isoprinosine powder for oral solution in a sachet was introduced on the market in Bulgaria in 2020. Children and adults who have trouble swallowing tablets or capsules may find powders for oral solution more acceptable. Dissolution rate of oral powders containing water-soluble drugs is generally faster than tablets or capsules, in which disintegration of the tablet or the capsule shell is required prior to dissolution. A disadvantage of powder forms is that they are bulky and inconvenient to be carried. A glass of water and a spoon are needed to dissolve the product before administration. Masking the unpleasant taste of the active substance can be a problem with this type of dosage form. The data of IMS Bulgaria for the annual sales in 2021 of Isoprinosine products are as follows: tablets 500 mg × 50 – 172 413 packages (5 849 313 BGN), powder for oral solution × 24 – 5 008 packages (183 472 BGN). Therefore, the share of tablets in sales is about 97% and it is the most preferred form by patients.
Tablets 1000 mg
In the Summary of product characteristics of Neosine forte tablets, the following excipients are described: wheat starch, mannitol, povidone and magnesium stearate. The literature review shows there are no articles on the pharmaceutical development of
The approach to develop a higher dose of a solid dosage form i.e. tablets in pharmaceutical and regulatory practice is usually based on the principle of proportionality. Preliminary experiments have shown this principle is not fully applicable in the case of the
On the other hand, in the development of a 500 mg tablet, the solvent ethanol 96%: water = 1: 1 for granulation is used, and in industry only water is preferred as a solvent due to ecological and explosiveness related concerns
Therefore, the aim of this work is to evaluate and compare the effect of some commonly used binders and develop a 1000 mg
Inosine Acedoben Dimepranol (ABC Farmaceutici S.p.A., Italy), wheat starch (Roquette), povidone K25 (Kollidon 25, 30 BTC Europe GmbH/ BASF), pregelatinized starch (starch 1500, Colorcon), Macrogol 6000 (Clariant), microcrystalline cellulose PH 102 (Vivapur JRS Pharma), mannitol (Pearlitol 200 SD, Roquette), glycerol dibehenate (Compritol 888 ATO, GATTEFOSSE), magnesium stearate (Peter Greven); all excipients meet the requirements of Ph. Eur.
The compositions of a series of laboratory batches are presented in Table
The size of the laboratory batches is 1 000 tablets (1292 g).
The wet granulation method is used for the production of all batches.
The ingredients are measured according to the recipe and sieved through a sieve with a pore size of 1.25 mm.
Compositions of laboratory batches.
Ingredients mg/tabl | Batch № | |||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|
IF L01 | % w/w | IF L02 | % w/w | IF L03 | % w/w | IF L04 | % w/w | IF L05 | % w/w | IF L06 | % w/w | |
|
||||||||||||
Inosine Acedoben Dimepranol | 1000.0 | 77.40 | 1000.0 | 77.40 | 1000.0 | 77.40 | 1000.0 | 77.40 | 1000.0 | 77.40 | 1000.0 | 77.40 |
Wheat starch | 120.0 | 9.29 | 116.0 | 8.98 | – | – | 116.0 | 8.98 | – | – | 116.0 | 8.98 |
Kollidon K25 | 50.0 | 3.87 | 50.0 | 3.87 | 50.0 | 3.87 | 50.0 | 3.87 | – | – | – | – |
Starch 1500 | – | – | – | – | 116.0 | 8.98 | – | – | 166.0 | 12.85 | – | – |
Macrogol 6000 | – | – | – | – | – | – | – | – | – | – | 50.0 | 3.87 |
Water purified* | 45.0 | 45.0 | 45.0 | 45.0 | 60.0 | 50.0 | ||||||
|
||||||||||||
Granules |
1166.0 | 1166.0 | 1166.0 | 1166.0 | 1166.0 | 1166.0 | ||||||
Microcrystalline cellulose PH 102 | – | – | – | – | – | – | 34.0 | 2.63 | 34.0 | 2.63 | 34.0 | 2.63 |
Mannitol 200 SD | 34.0 | 2.63 | 34.0 | 2.63 | 34.0 | 2.63 | – | – | – | – | – | – |
Wheat starch | 48.0 | 3.72 | 48.0 | 3.72 | – | – | 48.0 | 3.72 | – | – | 48.0 | 3.72 |
Starch 1500 | – | – | – | – | 48.0 | 3.72 | – | – | 48.0 | 3.72 | – | – |
Glycerol dibehenate | 40.0 | 3.10 | 38.0 | 2.94 | 38.0 | 2.94 | 38.0 | 2.94 | 38.0 | 2.94 | 38.0 | 2.94 |
Magnesium stearate | – | – | 6.0 | 0.46 | 6.0 | 0.46 | 6.0 | 0.46 | 6.0 | 0.46 | 6.0 | 0.46 |
|
1292.0 | 100.0 | 1292.0 | 100.0 | 1292.0 | 100.0 | 1292.0 | 100.0 | 1292.0 | 100.0 | 1292.0 | 100.0 |
* The solvent evaporates during the production process
The method for wet granulation is chosen, characterized by the ability to formulate high-dose tablets, as it is the case with this developed product. Other reasons behind are as follows:
Bulk density increase, which is due to multiple increase in the size of dust particles, which gives them excellent flow properties;
The binding properties of the powders are improved, whereby they acquire the property of cohesiveness, which is especially important for obtaining of quality tablets.
The povidone binder is included in a powder form in the granulation mixture and granulated
Purified water was used as the granulation fluid to form the wetted mass of all formulations except IF L06, in which an aqueous solution of macrogol 6000 was used. The results of the tested physicochemical parameters of the batches are presented in Table
Results of tested physicochemical parameters.
Tested parameters | Evaluation | |||||
---|---|---|---|---|---|---|
IF L01 | IF L02 | IF L03 | IF L04 | IF L05 | IF L06 | |
Bulk density of granules, g/ml | 0.500 | 0.476 | 0.488 | 0.476 | 0.500 | 0.500 |
Tapped density, g/ml | 0.541 | 0.556 | 0.541 | 0.526 | 0.500 | 0.526 |
Hausner ratio of granules | 1.081 | 1.167 | 1.108 | 1.105 | 1.000 | 1.053 |
Residual moisture of granules, % | 2.8 | 2.4 | 2.6 | 2.2 | 2.9 | 2.7 |
Average mass per tablet (mg) | 1293.2 | 1295.4 | 1293.8 | 1294.2 | 1294.6 | 1293.4 |
Hardness (N) n = 10; ± SD | 60 ± 5.5 | 65 ± 6.4 | 75 ± 5.6 | 96 ± 6.8 | 55 ± 7.6 | 45 ± 7.2 |
Disintegration (min) | 10.0 | 10.0 | 11.0 | 10.0 | 12.0 | 9.0 |
Friability (%) | 0.68 | 0.62 | 0.58 | 0.51 | 0.84 | 0.73 |
Defects in the appearance of the tablets, % | 3.0 | no | no | no | no | 1.0 |
With regards to the „flow” property of the granules, the „Hausner ratio“ data showed all batches have good criterion values < 1.25.
The composition of batch IF L01 is almost twice proportional to the established composition of
In the composition IF L03, wheat starch was replaced by starch 1500TM. This is a starch that has been previously gelatinized and dried to powder form. Partially pregelatinized starches have a mixture of properties of both native and fully gelatinized starches. This makes them useful as both a binder and a disintegrant in wet granulated formulations. Starch 1500 can be added directly to the granulator bowl and water can be utilized to granulate. The results show there is no significant change in the properties of the tablets.
The composition IF L05 was prepared according to the instructions of Colorcon for the application of starch 1500 to water-soluble active substances (
In the composition IF L06, another wet granulation binder is being experimented with macrogol 6000, which is typically used for water-soluble active substances. In solid dosage formulations, higher molecular weight polyethylene glycols can enhance the effectiveness of tablet binders and impart plasticity of granules. The use of polyethylene glycols is proposed, since it has been verified that the same when in solution, act not only as binder in the granulation process, but also effectively contributes to the increase of density of the granules, reducing the volume originally occupied by the active principles (
From the evaluation of the results, the following effects of binders are observed:
The strongest and most suitable binder for the granules is povidone in combination with wheat starch, as also was found for the dose of 500 mg tablets. Wheat starch can be replaced by pregelatinized starch, but it is much more expensive and economically not justified.
Using only water as a binder solvent does not affect the properties of the resulting granules.
The inclusion of microcrystalline cellulose in the external phase of the composition further strengthens the binding properties and allows obtaining 1000 mg tablets with the desired properties.
The use of mannitol as a binder in the external phase of the composition is not effective for the 1000 mg dose.
Dissolution tests were performed according to the guidelines of Ph Eur “Recommendation on dissolution testing” and the monograph “Dissolution test for solid dosage forms”, as well as the EMA 2010 guidelines “Guideline on the investigation of bioequivalence” and “Reflection paper on dissolution specification for generic solid oral immediate release products with systemic action“.
The active ingredient is not included in any pharmacopoeia.
The established conditions and procedure for testing the dose of
According to the data for dissolution of
Experiments were performed for comparison of the dissolution profiles between
Comparative dissolution profile of
Comparative dissolution profile of
The dissolution test was also carried out with sample IF L03 in order to evaluate the effect of the binder pregelatinized starch (Fig.
The dissolution profiles of both products show similar behavior and are characterized as similarly rapid - 85% of the active substance is released within 30 min.
Dissolution profile of
To demonstrate the similarity of dissolution profiles according to the Guideline on the investigation of bioequivalence, the value of the similarity factor f2 is calculated:
f2 inosine = 79.19 and
f2 4 - acetamidobenzoic acid salt = 80.66
According to criterion f2 requirement, values between 50 and 100 indicate the similarity of the dissolution profiles of the two products.
The dissolution profiles of both products show similar behavior and are characterized by a certain delay in the release of the active substance compared to the medium at pH 6.8.
To demonstrate the similarity of dissolution profiles according to CPMP/EWP/QWP/1401/98 Rev. 1 /Corr **, the value of the similarity factor f2 is calculated.
The result obtained is as follows:
f2 inosine = 76.47 and
f2 4 - acetamidobenzoic acid salt = 85.24
According to criterion f2 requirement, values between 50 and 100 indicate the similarity of the dissolution profiles of the two products.
The data show that in the medium with pH 1.2, the dissolved amount of
The dissolution profile of sample IF L03, in which wheat starch is replaced by the pregelatinized starch, is also characterized as rapid - 85% of the active substance is released within 30 min. Therefore, the Starch 1500TM/Povidone binder combination favors the immediate release of
Tablet Batch IF L04 was packed in a blister consisting of PVC /PVdC film (250 μm /40 g /m2), thermally sealed with aluminum foil (20 μm) and stability tests were performed under accelerated conditions - 40 °C /75% RH for six months according to Note for guidance on stability testing.
The analytical results are presented in Table
Stability study tablet batch № IF L04.
Test | Specification | Initial analysis | Testing after 3 months | Testing after 6 months |
---|---|---|---|---|
1. Appearance | White to off-white, oblong, biconvex tablets with a slight ammonia odor | Complies | Complies | Complies |
2. Identification Inosine Acedoben Dimepranol | Compliance with the tests | Meets the tests | Meets the tests | Meets the tests |
– UV absorption | ||||
– HPLC | ||||
3. Average mass, mg /tablet and uniformity of mass, mg | From 1227.4 to 1356.6 (1292 ± 5%) | 1294.2 Complies | 1294.6 Complies | 1294.8 Complies |
4. Disintegration, min | Not more than 15 | 10.0 | 10.0 | 10.0 |
5. Dissolution, %, within 30 min: Inosine 4-acetamidobenzoic acid salt | Not less than 80 (Q=75) Not less than 80 (Q=75) | 93 98 | 92 96 | 90 95 |
6. Impurities, HLPC: | ||||
6.1 Hypoxanthine, % | Not more than 0.2 | n.d. | n.d. | 0.02 |
6.2 4-aminobenzoic acid salt, % | Not more than 0.2 | 0.05 | 0.06 | 0.09 |
6.3 Each unspecified impurity, % | Not more than 0.1 | n.d. | < LOQ | < LOQ |
6.4 Total impurities, % | Not more than 0.5 | 0.05 | 0.06 | 0.11 |
7. Content of |
240.50 (95.0–105.0%) 759.50 (95.0–105.0%) 1000.00 (95.0–105.0%) | 233.46 770.66 1004.12 | 233.04 770.22 1003.26 | 232.32 769.43 1001.75 |
The results of the batch impurity profile after 6 months of storage under accelerated conditions did not show any significant change. No changes in the physicochemical parameters of the tablets were observed. The results correspond to the product specification.
Wet granulation technique can be successfully used to overcome the poor compression properties of Inosine Acedoben Dimepranol powder and also to produce high-dose 1000 mg tablets with immediate release of the active substance.
Wet granulation was tested with several binders - Wheat starch /Povidone; Starch 1500TM/ Povidone, Starch 1500TM and Macrogol 6000.
The Wheat starch /Povidone and Starch 1500TM/ Povidone mixtures, including microcrystalline cellulose in the outer phase were found to be the best for producing
The optimal lubricant system is glycerol dibehenate /magnesium stearate.
A similarity of the dissolution profile of the 1000 mg
The results of the stability study indicate that the tablets remain stable under the conditions of observation.