Oral pharmaceutical compositions in unit dosage form

Abstract: Oral pharmaceutical compositions in unit dosage form, especially capsules, comprising solid Colloidal Bismuth Subcitrate (CBS), optionally one or more auxilliary medicaments and excipients, the dosage units having a packing density of between 0.06 and 0.60 grams of CBS per ml.

Description: This invention relates to oral pharmaceutical compositions in unit dosage form, comprising solid Colloidal Bismuth Subcitrate. Solid Colloidal Bismuth Subcitrate (CBS), compositions thereof being sold under the trademark De-Nol®, is the product obtained by the process of European Patent 0,075,992, corresponding to U.S. Patent 4,801,608. It is also the active ingredient obtained by the process of British Patent 1,478,742. According to these specifications, CBS can be formulated into pharmaceutical compositions in solid dosage form for oral administration, such as tablets and capsules. Up to now only the tablet form has been realized and it is marketed in many countries. According to The Merck Index, 11th Edition (1989), item 1296, the approximate molecular formula of CBS is K₃(NH₄)₂[Bi₆O₃(OH)₅(C₆H₅O₇)₄]. Its bismuth content, when expressed as Bi₂O₃, is according to said European Patent 0,075,992 and British Patent 1,478,742, 39-42% by weight. The currently used swallowable tablet form of CBS has already been given to hundreds of thousands of patients and its clinical efficacy and safety have been firmly established. However, recently there have been reports of a transient sharp peak of bismuth blood level in humans after the ingestion of this CBS-containing swallowable tablet, t max around 30 minutes, see C.U. Nwokolo et al., Aliment. Pharmacol. Therap. 3 , (1989), 29-39. On the other hand, the values of the traditionally cited safe blood levels of bismuth have also been questioned recently, see for Example A. Slikkerveer and F. de Wolff, Med. Toxicol. Adverse Drug Exp. 4 (5) (1989), 303-323. Anyway, since the therapeutic action of CBS is localized in the gastrointestinal tract, even a transient peak of bismuth blood level does not appear to serve any useful purpose and should be avoided if possible. The object of the present invention therefore is to provide an oral dosage unit comprising CBS in a therapeutically effective amount, which does not cause the above described peak in the bismuth blood levels. This object has now been found to be met by oral pharmaceutical dosage units, comprising CBS prepared according to any of the above identified patent specifications, provided that the packing density of the CBS in the dosage units is between 0.06 and 0.60 g/ml. The term "packing density" as used herein, means the weight of the active ingredient (CBS) in grams divided by the volume occupied by the dosage unit expressed in milliliters, and, in case of a filled capsule form, excludes the volume and weight of the empty capsule. Thus, the packing density can be varied by varying the amount of excipients added to the CBS and by varying the pressure used in compressing the units. The invention therefore concerns oral pharmaceutical compositions in unit dosage form comprising a therapeutically effective amount of solid Colloidal Bismuth Subcitrate (CBS), and, optionally, pharmaceutically acceptable excipients, characterized in that the packing density of the CBS in the pharmaceutical dosage units is between 0.06 and 0.60 g/ml. Preferably, the packing density is between 0.30 and 0.50 g/ml. Figure 1 is a graphic representation of mean bismuth blood levels in dogs after ingestion of different CBS formulations. Figure 2 is a graphic representation of mean bismuth plasma levels in humans after ingestion of different CBS formulations. The CBS according to the invention is preferably present in the form of a granulate, having a preferred particle size of less than 1.5 mm. To the CBS may be added any of the excipients known in the art, which are compatible with CBS, such as: diluents, like lactose, starch, microcrystalline cellulose, sorbitol, mannitol, dibasic calcium phosphate dihydrate, calcium sulfate dihydrate, sucrose-based diluents and mixtures thereof; binders, like acacia, cellulose derivatives, gelatin, glucose, polyvinylpyrolidone, starch, sucrose, sorbitol, tragacanth, sodium alginate and mixtures thereof; disintegrants, like microcystalline cellulose and cellulose derivatives, starch and its derivatives, alginic acid and its derivatives, ion-exchange resins, cross-linked sodium carboxymethyl cellulose, sodium starch glycolate, cross-linked polyvinylpyrrolidone and formaldehyde-caseine; lubricants, antiadherents and glidants, like magnesium-, calcium- and sodium stearates, stearic acid, hydrogenated castor oil, talc, water, polyethylene glycol, sodium lauryl sulfate, magnesium lauryl sulfate and silica. These excipients are preferably added in a total amount ranging from 3-1000 mg, more preferably 20-150 mg, per 100 mg of CBS. A low packing density of oral dosage units as specified above is contrary to the current tendency in the art of pharmaceutical production, which is to concentrate the oral dosage units, e.g. by compressing the contents of oral capsules to a high density, see Hard Capsules, Development and Technology, Ed. K. Ridgway 1987, chapter 9, G.C. Cole, pp. 92-103. The oral dosage units of the present invention, when compared to swallowable tablets having the same formula and dosage of CBS but with a higher packing density, were found to give not only a lower maximal blood and plasma bismuth level (C max ), but also a lower bismuth bioavailability (AUC) and a lower bismuth excretion in the urine. Therefore, systemic bismuth absorption after ingestion of these dosage units has proved to be lower than after ingestion of the prior art tablets. This is contrary to the expectation that more dispersed material leads to its more rapid dissolution and consequently to its greater absorption than compressing the same material. The oral dosage units of the present invention surprisingly give maximum bismuth plasma levels and a total bismuth absorption which are lower than those of the dosage units with a higher packing density Besides CBS, the oral dosage units according to the invention may also contain additional medicaments, preferably those which are intended to act in combination with it, such as non-steroidal anti-inflammatory compounds, H₂-antagonists and synthetic prostaglandins. In particular the dosage units may contain antimicrobially effective medicaments such as antibiotics and chemotherapeutic compounds, more in particular medicaments effective against Helicobacter p ylori (formerly called Campylobacter pylori ), such as the antimicrobially effective nitro imidazoles, the β-lactam antibiotics such as the penicillins, cephalosporins, monobactams and penems, the tetracyclines, the quinolones and the macrolides. The preferred dosage of CBS in the oral dosage units according to the invention is 30-600 mg per dosage unit, more preferably 37.5-300 mg per dosage unit. The dosage of the optionally present additional medicaments will depend on the effectivity of the particular medicament used. The most practical oral dosage units according to the invention are capsules, although tablets having a low CBS packing density as defined above are also possible. The material of the swallowable capsules according to the invention may be any material known in the art, such as gelatine, a modified starch, such as hydroxyalkyl starch, and a cellulose derivative, such as a cellulose ether, e.g. methyl cellulose. Gelatine capsules can be soft or hard. The dosage units according to the invention may be further coated in order to provide controlled release. The following Examples will illustrate the invention. Example 1 CBS, prepared according to European Patent 0,075,992 and British Patent 4,801,608, was used to prepare tablets and capsules as follows: Uncoated round swallowable tablets A containing CBS were produced as follows: 100 kg of CBS were granulated with 23.8 kg of corn starch using 5.85 kg of povidone K30 dissolved in 51.0 kg of ethanol. The granulate, having a particle size of less than 1 mm, was blended with 7.8 kg of polacrilin potassium, 1.98 kg of polyethylene glycol 6000 and 0.66 kg of magnesium stearate, and compressed into tablets. Coated round swallowable tablets B containing CBS were produced by filmcoating compressed tablets, prepared as above described, with about 12 mg hydroxypropyl methylcellulose and about 2 mg polyethylene glycol per tablet. These tablets were identical to commercially used De-Nol® swallowable tablets. Coated elongated swallowable low packing density tablets C were produced as follows: 240 g of CBS were granulated with 480 g of corn starch, using 15 g of povidone K30 dissolved in 285 g of ethanol. The granulate, having a particle size of less than 1 mm, was blended with 19.4 g polacrilin potassium, 4.9 g polyethylene glycol 6000, 35.8 g corn starch and 3.6 g magnesium stearate, and compressed into tablets. The tablets were filmcoated with about 21 mg hydroxypropyl methylcellulose and about 3 mg polyethylene glycol per tablet. Swallowable capsules D with a low packing density and swallowable capsules E with a very low packing density of CBS were produced using the granulate for uncoated swallowable tablets A described above, filled into hard gelatin capsules No. 0, using a rotary capsule filling machine. The packing density of the capsule content was adjusted by setting of the piston within the dosator. The packing densities of the uncoated and coated tablets and of the contents of the two different capsules were calculated with respect to the amount of CBS per unit of volume. The disintegration time of the five formulations was measured in water at 37°C according to USP XXI. The hardness of the three tablet formulations was determined using the Schleuniger E-2 apparatus. The relevant properties of the five formulations are summarized in the following Table 1. Example 2 Bismuth absorption in dogs Healthy fasted dogs (Beagles) were given a single dose of the coated tablets B or C or the very low packing density capsule E of Example 1. The dogs were each dosed with 2 tablets or 2 capsules, giving a total dose of 600 mg CBS per dog. After ingestion, blood samples were taken at 9 intervals up to 8 hours. The bismuth content was measured in the blood by atomic absorption. The mean bismuth blood levels in the dogs after ingestion of the different CBS formulations are shown in Figure 1. Table 2 summarizes the mean values of: the blood t max (time after ingestion at which maximum bismuth blood level was reached); the blood C max (maximum bismuth blood level reached); the blood AUC (Area Under bismuth concentration-time Curve), calculated over a period of 8 hours after ingestion. From these results it becomes clear that in dogs the low packing density tablets and the very low packing density capsules gave a lower systemic bismuth absorption than did a prior art dosage form. Example 3 Bismuth absorption in humans Healthy fasted volunteers were given the uncoated and coated tablets A and B and the two capsules D and E of Example 1. The volunteers each took 2 tablets or 2 capsules, giving a total dose of 600 mg CBS per volunteer. After ingestion blood samples were taken at several intervals up to 3 hours, and the urine was collected for 3 hours. The bismuth content was measured in the plasma and in the urine by atomic absorption. The mean bismuth plasma levels in humans after ingestion of the different CBS formulations are shown in Figure 2. Table 3 summarizes the plasma and urine data (the AUC was calculated over a period of 3 hours after ingestion, the urine was collected over a period of 3 hours after ingestion). From the above results it becomes clear, that also in humans the very low packing density capsule gave a much lower systemic bismuth absorption than did the two prior art dosage forms, the low packing density capsule being intermediate. From Tables 3 and 1 there appears a reverse relationship between the density of the dosage form and the systemic bismuth absorption therefrom.

Claims: Claims for the following Contracting States :AT, BE, CH, DE, DK, FR, GB, IT, LI, LU, NL, SE An oral pharmaceutical composition in unit dosage form comprising a therapeutically effective amount of solid Colloidal Bismuth Subcitrate (CBS) and, optionally, pharmaceutically acceptable excipients, characterized in that the packing density of the CBS in each unit of the pharmaceutical composition is between 0.06 and 0.60 g/ml. An oral pharmaceutical composition according to claim 1, characterized in that the packing density is between 0.30 and 0.50 g/ml. An oral pharmaceutical composition according to claim 1 or 2, characterized in that the content of solid Colloidal Bismuth Subcitrate is between 30 and 600 mg per dosage unit. An oral pharmaceutical composition according to claim 3, characterized in that the content of solid Colloidal Bismuth Subcitrate is between 37.5 and 300 mg per dosage unit. An oral pharmaceutical composition according to any one of claims 1-4, characterized in that the composition contains at least one additional medicament. An oral pharmaceutical composition according to claim 5, characterized in that the additional medicament is an antimicrobial. An oral pharmaceutical composition according to claim 6, characterized in that the antimicrobial is one which is effective against Helicobacter ( Campylobacter ) pylori , chosen from the groups of the nitro imidazoles, penicillins, cephalosporins, monobactams, penems, tetracyclines, quinolones and macrolides. An oral pharmaceutical composition according to any one of claims 1-7, characterized in that the composition is a capsule. Capsule according to claim 8, characterized in that the material of the capsule is chosen from the group of gelatine, a modified starch and a cellulose derivative. Claims for the following Contracting States : ES, GR Process for the preparation of an oral pharmaceutical composition in unit dosage form comprising a therapeutically effective amount of solid Colloidal Bismuth Subcitrate (CBS) and, optionally, pharmaceutically acceptable excipients, characterized in that the packing density of the CBS in each unit of the pharmaceutical composition is between 0.06 and 0.60 g/ml. Process according to claim 1, characterized in that the packing density is between 0.30 and 0.50 g/ml. Process according to claim 1 or 2, characterized in that the content of solid Colloidal Bismuth Subcitrate is between 30 and 600 mg per dosage unit. Process according to claim 3, characterized in that the content of solid Colloidal Bismuth Subcitrate is between 37.5 and 300 mg per dosage unit. Process according to any one of claims 1-4, characterized in that the composition contains at least one additional medicament. Process according to claim 5, characterized in that the additional medicament is an antimicrobial. Process according to claim 6, characterized in that the antimicrobial is one which is effective against Helicobacter ( Campylobacter ) pylori , chosen from the groups of the nitro imidazoles, penicillins, cephalosporins, monobactams, penems, tetracyclines, quinolones and macrolides. Process according to any one of claims 1-7, characterized in that the composition is a capsule. Process for the preparation of the capsule according to claim 8, characterized in that the material of the capsule is chosen from the group of gelatine, a modified starch and a cellulose derivative.

Inventors: GROENENDAAL JAN WILLEM, MUHLENBRUCH AART, GROENENDAAL, JAN WILLEM, MUHLENBRUCH, AART
Applicants: BROCADES PHARMA BV, BROCADES PHARMA B.V.
Application year: 1991
Main classification: A61K31
IPC codes: A61K9, A61K45, A61K33, A61K31