United States Patent [19] [11] Patent Number: 4,704,278 Wu Et Al

United States Patent [19] [11] Patent Number: 4,704,278 Wu et al. [45] Date of Patent: :1: Nov. 3, 1987

[54] FLUIDIZED MAGALDRATE SUSPENSION 4,117,116 9/1978 Buehler et a1...... 424/158 [75] Inventors: Chien-Chin Wu, Wilmington, Del.; OTHER PUBLICATIONS Gerald L‘ Renter’ Plattsburgh’ NY‘ Handbook on Nonprescription Drugs, Fifth Edition [73] Assignee: American Home Products Corp (Del), (1977), p. 16, American Pharmaceutical Assoc, Wash. New York, N.Y. D.C. [ * 1 Notice The portion of the term of this patent Primary Examiner-Frederick E. Waddell subsequent to Jun. 30, 2004 has been disclaimed. [57] ABSTRACT , [211 App], N03 395,012 An aqueous antacid composition of magaldrate gel and _ . a process for preparing same are described by the inven [22] F11e d'' A ug' 8 ’ 1986 t1on.- The composltlon- - is prepared from and contains _ . precipitated and undried magaldrate gel and a ?uidizing Related U‘S' Apphcatlon Data of a ?rst and second ?uidizer. On fluidizer is provided [63] Continuation of Ser. No. 661,648, Oct. 17, 1984, aban~ by an aluminum hydroxide gel having colloidal proper doned’ ties and the second by a pharmaceutically acceptable [51] Int. (:1.4 ...... A61K 33/08 citrate ion source including citric acid- The Process and [52] US. Cl...... 424/157; 424/158 compositiw are characterized in Providing a ?uid, [5 8] Field of Search ...... 424/157, 158 resuspendlble, pharmaceutically elegant suspension POS _ ' sessing high antacid capacity and stability at even ele [56] References cued vated magaldrate concentrations in addition to the abil U.S. PATENT DOCUMENTS ity to ?uidize stiff, paste-like magaldrate gel cakes. 4,112,072 9/1978 Rubino et a1...... 424/158 4,115,553 9/1978 Rubino et a1...... 424/158 3 Claims, No Drawings 4,704,278 1 2 colloidal properties and a loss of ?uidity or mobility. FLUIDIZED MAGALDRATE SUSPENSION Even where ?uidity is initially maintained or achieved, further requirements of pharmaceutically acceptable This is a continuation of application Ser. No. 661,648, aqueous antacid suspensions call for a smooth (non ?led Oct. 17, 1984, now abondoned. gritty) mouth feel and maintenance of a gel structure for both suspendibility and resuspendibility. In general, BACKGROUND OF THE INVENTION resuspendible, aqueous antacid suspensions are typically 1. Field of the Invention de-?occulated products which contain a de?occulant This invention relates to resuspendible, pharmaceuti or suspending agent to arrest or control further agglom cally elegant high concentration, low viscosity, aqueous eration or ?occulation and settling. In the absence of a ' antacid suspension dosage forms for oral administration de?occulant or suspending agent type additive, the and to methods for their preparation and use. antacid in a suspension forms a hard cake or a gel struc 2. Decription of the Antacid Art ture which can no longer be resuspended with its origi Antacids are widely used in the treatment of gastroin nal desirable characteristics. The formation of such a testinal disorders. Their effectiveness in promoting the cake or gel structure is independent of antacid concen healing of gastric and duodenal ulcers has been well tration except for low antacid concentration. documented. Essentially, antacids exert their positive The de?occulants and suspending agents have been effects by neutralizing the gastric acid secreted in the frequently included in the formulation of aqueous ant stomach. When the pH of stomach contents is raised acid suspensions containing solid antacid concentrations above 3, most gastric acid is neutralized and the proteo 20 in the range of about 6 to 12 percent to prevent caking. lytic activity of pepsin is inhibited. The recent elevation With the growing interest in providing antacid suspen of antacids to a major therapeutic role, particularly in sion dosage forms with a greater acid neutralizing ca ulcer therapy, rather than a merely pallative role, has pacity, means were sought to provide highly concen emphasized the importance of providing antacid prod trated but fluid systems. ucts featuring a high neutralization (and buffer) capac 25 US. Pat. No. 3,579,634 describes an antacid composi ity as well as a rapid rate of gastric acid neutralization. tion containing as the essential ingredients an antacid These features particularly that of rapid rate of neutral and a water dispersible, colloidal anionic ether or ester ization to the neutralization capacity of the antacid derivative of a low polymer of a monosaccharide as a de?ne the more effective antacid in vivo since it is less gelation agent, the gelation agent being such that a likely that unconsumed antacids will be removed by 30 thickened gel-like consistency occurs upon interaction normal gastric emptying. of the composition with gastro-intestinal mucous so as Most antacids are available in both liquid and solid to adhere thereto. The gelation agent in vitro is de dosage forms. The liquid antacids, as aqueous suspen scribed as providing ?uidity to concentrated suspen sions, are, generally, more effective than the same ant sions, and the starting actacid may be selected from acids in solid dosage forms and are more commonly powder, granule or paste forms of certain calcium, alu prescribed in the hospital. The greater effectiveness of minum, magnesium, sodium and bismouth antacids. The liquid antacids is partially due to the large surface area antacid suspension compositions disclosed therein ap available in liquid suspensions to react with gastric acid pear to initially require milling, high energy agitation or and partially due to the great amount of colloidal parti homogenization to eliminate the grittiness of the antacid cles in aqueous suspension which can more easily reach ingredient. the affected area where treatment is needed. Moreover, In U.S. Pat. No. 3,591,680, high concentration ant aqueous suspensions of undehydrated antacids are more acid suspensions are disclosed containing about 25 to 50 reactive than dry or solid antacids. . percent weight/volume of certain selected solid antacid While liquid antacids possess these advantages, the materials suspended in an aqueous vehicle containing same require administration of relatively large volumes 45 certain speci?ed suspending agents of which a de?nd of liquid suspension. The ingestion of such large vol hydroxypropyl cellulose is preferred. While these sus umes is inconvenient, however, making the normal pension are said to provide stable and palatable, high problem of assuring patient compliance outside the concentration suspensions, the preferred composition is hospital environment even more difficult. Since high stated to provide only a minimum of 2 months of contin dose regimes of liquid antacid have recently been ued ?uidity and pourability. Such standards are not shown to be effective both in promoting the healing of acceptable for a commercial product in which shelf life duodenal ulcers and in preventing the acute upper gas stability should extend for at least 1-2 years. trointestinal bleeding in critically ill patients, the use of US. Pat. No. 3,347,744 discloses a high concentration regular liquid antacid suspensions with the usual solid magnesium hydroxide suspension containing up to 30% antacid content in the 6-12 percent range has become of that antacid with a cellulosic suspending agent and even more impractical for such therapeutic indications. submicroscopic silica. The suspension is said to avoid The most widely used antacids can be described as the clumping and caking common among even lower mineral type, insoluble inorganic salts that are hydrated, concentration magnesium hydroxide suspensions, al possess colloidal properties, and contain, for example, though there is no disclosure that the suspension is aluminum, magnesium, bismouth and the like. Com thereby rendered more ?uid. pounds of the described mineral variety in their freshly More recently, in US Pat. No. 4,117,116, there is prepared, hydrated form and in suspensions therefrom disclosed a method for lowering the viscosity of a com provide some of the characteristics desired in an ant mercially available aqueous antacid gel cake to render acid. To provide liquid antacids with a high neutraliza the same pumpable in the production environment. The tion capacity it is necessary to increase the solids con 65 gel cake represents a magnesium hydroxide antacid, an centration of the antacid components. Such increases in aluminum hydroxide antacid or a mixture thereof and concentration, however, are accompanied at higher the antacid is 25-35% weight by weight of the gel cake levels with exponential increases in viscosity, a loss in before processing. The method comprises mixing into 4,704,278 3 4 the gel cake a ?uidizing agent selected from acacia, equivalent of not less than 18.0 percent and not more citric acid, sodium citrate, sodium lauryl sulfate or dioc than 26.0 percent of aluminum oxide (A1203). tyl sodium sulfosuccinate and the ?uidizing agent The preparation of magaldrate is described in US amounts to 0.l—4% of the ?nal total mixture. Pat. No. 2,923,660. A commercially suitable procedure It is an object of this invention to provide magaldrate, is described in said patent, for example, beginning in aqueous antacid suspensions with high antacid capacity column 2, line 40, although to maintain a low sodium and good mouth feel characteristics. content for the ?nal product, the use of potassium oxide Another object of this invention is to provide magal (or hydroxide) is preferred over the discloed sodium drate, aqueous antacid suspensions with high antacid oxide. Typically the magaldrate is precipitated to pro- ‘ capacity and which retain, at high concentrations, the vide a 6% weight/volume mixture (?uid when fresh) desirable qualities of rapid acid neutralization and reli and diluted to 3% or washing prior to concentration ably uniform reaction in acidic solutions. and formulation into a suspension providing a so called A further object of the invention is to provide high single strength neutralization capacity (ANC) of 13.5 to antacid capacity, aqueous magaldrate suspensions with 15 meq per 5 milliliters of suspension which is equiva good ?uidity, pourability and suspension characteristics lent to a magaldrate weight/weight concentration in and which further provides full resuspendibility under the range of about 12 to 13 percent solids. At this con the typical shelf life conditions for a commercial aque centration, unformulated, magaldrate is a paste-like gel. ous antacid suspension. In one commercial embodiment sold under the RIO SUMMARY OF THE INVENTION PAN trademark, the magaldrate is formulated with 20 acacia gum to reduce the gel viscosity and achieve In accordance with this invention there is provided satisfactory ?uidization. While acacia is suitable as a aqueous antacid compositions characterized in provid ?uidizer for the so called single strength magaldrate ing a ?uid, resuspendible, pharmaceutically elegant product and is reported to be suitable for lowering the antacid suspension with high antacid capacity. The viscosity of a concentrated commercially aqueous ant composition comprises precipitated and undried magal 25 acid gel cake consisting of aluminum or magnesium drate gel and a ?uidizing amount of a combination of an hydroxide or a physical mixture of the two hydroxides, aluminum hydroxide gel having colloidal properties as a the same is not suitable for providing a magaldrate ?rst ?uidizer and a second ?uidizer selected from at product providing greater than about 22 milliequiva least one from the group consisting of citric acid and a lents per 5 ml of ANC and the high antacid capacity pharmaceutically acceptable citrate ion source. 30 In another embodiment, the invention includes a composition of this invention. It is hardly surprising method for producing aqueous antacid composition of that the usefulness reported for acacia in liquifying high antacid capacity and which are characterized in aluminum or magnesium hydroxide antacids or mix providing ?uid, resuspendible pharmaceutically elegant tures thereof does not extend to magaldrate, since their antacid suspensions of magaldrate. The method com 35 crystal structures have been reported to be distinct. prises mixing a precipitated and undried magaldrate gel Thus, while magaldrate has a great similarity structur with a ?uidizing combination of a ?rst and second ?uid ally to the naturally occurring minerals hydrotalcite izer. The ?rst ?uidizer is selected from an aluminum and motukoreaite, and is believed to contain sulfate as hydroxide gel having colloidal properties and the sec the major interlayer, with a small amount of carbonate ond ?uidizer is selected from at least one from the 40 impurity, magnesium hydroxide is most similar to the ‘group consisting of citric acid and a pharmaceutically mineral brucite and aluminum hydroxide has a disor ' acceptable citrate ion source. The method for produc dered, amorphous polymeric structure. The physical ing the high antacid capacity, aqueous antacid composi mixtures of some aluminum and magnesium hydroxides tions of the invention may be broadly approached and have been reported to form hydrotalcite type structures achieved, for example, either by prior concentration of 45 on aging while retaining many brucite characteristics. the magaldrate gel cake into a high concentration paste Mere ?uidization or de?oculation of an aqueous sus followed by its ?uidization with a ?uidizing amount of pension dosage is, however, only one factor in the for the combination of the ?rst and second ?uidizer, or, by mulation of an aqueous antacid susension. Thus, no concentration of a ?uid and relatively low concentra advantage arises from increased ?uidization of more tion magaldrate gel'cake previous mixed with a ?uidiz highly concentrated suspension if ?uidization is ing amount of the combination of the ?rst and second achieved at the expense of resuspendibility or loss of ?uidizer. rate or extent of acid neutralization capacity or antacid The magaldrate of the invention is the precipitated, buffer capacity, immediately or upon aging. This con undried form of the antacid. This description refers to cern is especially acute for an aqueous antacid suspen magaldrate gel which has not been previously dried to sion comprising magladrate as the predominant antacid its hydrated, anhydrous form. because of its exceptional balance of desirable antacid properties within a single chemical entity—i.e., rapid DETAILED DESCRIPTION OF THE reaction rate, prolonged buffering action within the INVENTION therapeutically desired range and good acid-consuming Magaldrate is a chemical combination of aluminum 60 capacity. With this invention, the desirable balance of and magnesium hydroxide, corresponding approxi magaldrate antacid properties is retained while the rhe mately to the formula Al5Mg10(OH)31(SO41)ZXHZO, ological properties of the magaldrate gels are signi? according to the of?cial monograph USP XX, third cantly altered, thereby enabling the provision of con supplement USP-NF, and has a molecular weight of centrated, high antacid capacity magaldrate suspension. about 1097.4. Magaldrate, also sometimes referred in 65 An additional bene?t accompanying this invention is said monograph as aluminum magnesium hydroxidesul the uniformity of desirable rheological properties ob fate, contains not less than 29.0 percent and not more tained which reduces or eliminates the batch to batch than 40.0 percent of magnesium oxide (MgO) and the ?ne tuning frequently required to deal with the unpre 4,704,278 5 6 dictability usually inherent in the rheological properties Thus in one aspect the method of this invention com of both ?uidized and un?uidized magaldrate gels. prises: Accordingly this invention relates to an aqueous ant (a) mixing a low concentration of a precipitated and acid composition characterized in providing a ?uid, undried magaldrate gel with a ?uidizing amount of a resuspendible, pharmaceutically elegant antacid suspen combination of an aluminum hydroxide gel having col sion with high antacid capacity. This composition com loidal properties as a first ?uidizer and a second ?uid prises precipitated and undried magaldrate gel and a izer selected from at least one from the group consisting ?uidizing amount of a combination of an aluminum of citric acid and a pharmaceutically acceptable citrate hydroxide gel having colloidal properties as a ?rst ?uid ion source; izer and a second ?uidizer selected from at least one (b) concentrating the mixture of step (a) to a ?uid from the group consisting of citric acid and a pharma high antacid capacity aqueous magaldrate suspension. ceutically acceptable citrate ion source. Alternatively, the steps of the method of the inven As previously described the magaldrate gel of this tion may be reversed so that the magaldrate gel is ?rst invention refers to precipitated magaldrate which has concentrated to a concentration providing a high ant not previously been dried to its hydrated, anhydrous acid capacity and then ?uidized by mixing the concen form. While the ?uidizing combination contained in the trate magaldrate gel with a ?uidizing amount of a com composition of the invention may very well ?uidize an bination of the ?rst and second ?uidizer of the inven aqueous mixture employing anhydrous magaldrate gel, tion. a composition therefrom will not possess the desirable In a preferred embodiment the method of the inven combination of suspension, resuspendibility, colloidal tion comprises: and antacid properties provided by the composition of (a) forming an aqueous mixture containing a ?uidiz the invention. Moreover, it is preferred in the composi ing amount of a combination of an aluminum hydroxide tion: of the invention to utilize freshly precipitated ma gel having colloidal properties as a ?rst ?uidizer and a galdrate gel since the use of older gels appears to re second ?uidizer selected from at least one from the quire relatively higher proportions of the ?uidizing group consisting of citric acid anda pharmaceutically acceptable citrate ion source; combinations than the same composition comprising (b) concentrating a precipitated and undried magal freshly precipitated magaldrate gels. drate gel to high antacid capacity; In contrast to most currently available antacid sus (0) incrementally and continuosly charging and mix pensions and to commercial magaldrate antacid suspen ing the concentrated magaldrate gel into a stream of the sions which provide an ANC of about 13.5 meq/S ml, mixture containing said ?uidizers thereby ?uidizing the the composition of this invention readily provides an concentrated gel into a ?uid suspension; and acid neutralization capacity (double strength) of at least (d) incrementally and continuously charging and 25-30 meq/5 ml or of at least about 17-18% to about mixing additional concentrated magaldrate gel into 20% weight/weight or about 18 to about 22% weight a continuosly recycled stream of the increasingly /volume. It will be appreciated that less concentrated concentrated ?uidized suspension to provide a suspensions such as those having an ANC of 13.5 meq/S ?uidized high antacid capacity magaldrate suspen ml are, also, easily achievable by the composition and sion. method of this invention. The upper limit to the ANC The concentrations and proportions of materials used and concentration of the composition of this invention in the method of the invention are the same as those ‘ ‘is only limited by the equipment available, but is be described for the composition of the invention and will ‘ 'lieved to be on the order of 50-60 meq/S ml. be based on the magaldrate concentration of the ?uid The ratio on a dry basis of magaldrate to the ?uidiz ized suspension. Thus, the concentration of the magal ‘ ing combination will range from about 25:1 to about 2:1, drate in step (b) of the hereinabove described method and preferrably from about 8:1 to about 4:1. For exam 45 will exceed the ?nal concentration of the suspensions. ple, in a composition having 216 g magaldrate per liter Also, as with the composition of the invention, the of suspension, the 25:1 to 2:1 ratio would correspond to method of the invention preferably employs freshly about 8.0 g/l to about 104 g/liter of ?uidizers. precipitated magaldrate gel. The ratio on a dry basis of the ?rst ?uidizer, alumi The composition of the invention can also and usually num hydroxide gel, calculated as aluminum oxide to the does include a number of pharmaceutically acceptable second ?uidizer will range from about,1:15 to about 1:1, excipients which are conventional in the aqueous ant preferrably from about 1:6 to about 1:2 and most prefer acid suspension art and do not form part of the inven rably in a range of about 1:4. For example, in a composi tion. Such excipients include one or more ?avoring tion having 216 g magaldrate per liter of suspension in a agents e.g. peppemint, etc; sweetening agents, e.g. sac ratio to ?uidizers of 8:1 or 27 g/l of ?uidizers the 1:4 55 charin, sorbitol, preservatives; sanitizers; body-building ratio of ?rst ?uidizer to second ?uidizer would corre agents and the like. spond to about 5.4 g/l of ?rst ?uidizer and 21.6 g/l of The composition of this invention may also contain second ?uidizer. other therapeutically active substances such as anti?atu In another embodiment, ‘the invention relates to a lents, as for example, simethicone, algin derivatives for method for providing or preparing aqueous antacid 60 treatment of esophogeal re?ux; analgesics such as acet comositions of high antacid capacity and which are aminophen, ibuprofen and protected aspirin; various further characterized in providing ?uid, resuspendible antidiarrheal or parasympatholytic agents; antiulcer pharmaceutically elegant antacid suspensions of magal agents such as cimetidine, ranitidine and sucralfate; and drate. The method broadly comprising mixing a precip others. itated and undried magaldrate gel with a ?uidizing com 65 Compositions of this invention are useful in the treat bination of the ?rst and second ?uidizer of this inven ment of a variety of gastrointestinal disorders in man or tion. Moreover, mixing can be done prior or subsequent animals. Typical of such disorders are hyperchlorhy to concentration of the magaldrate gel. dria, peptic ulcer, gastic ulcer, duodenal ulcer, gastritis, 4,704,278 7 8 esophagitis, hiatal hernia, and other digestive disturb particle size distribution, mobility and resuspendibility ances. As noted earlier, the composition of this inven (5 hand shakes). tion is especially useful in the treatment of disorders that EXAMPLE 2 demand the antacid to play a therapeutic role rather than a mere pallative role. The dosage form for the composition of this invention will normally be adminis Ingredient Amount (mg) tered orally. In general, the therapeutic dosage of the Magaldrate Gel 170.8 composition can be determined by relationship to the Aluminum Hydroxide (colloidal) 8.1 ANC of same to that of known antacid dosage forms. Potassium Citrate 34.2 Saceharin 0.4 While not wishing to be bound by any theory of Sorbitol Solution (70%) 50.0 invention, it is hypothesized that magaldrate prepared Gylcerine 50.0 by the processes earlier described, contains small parti Peppermint ?avor 0.3 cles with a resulting greater surface area and higher Water q.s. 1000.0 surface charges. Witha material such as just described, one in which it is essential to maintain the colloidal The magaldrate composition of the invention in this properties of the magaldrate to guarantee its most effi example provided a suspension having about 17.1% cacious values over a useful shelf-life, control of viscos magaldrate solids with an approximate ANC of 24 ity is critical, and, is rendered more difficult in increas meq/ 5 ml. ing concentrations. This control is achieved with a The composition of this example was prepared as ?uidizing amount of a combination of the ?rst and sec described in Example 1 and with the same results. ond ?uidizer whereby the second ?uidizer. apparently EXAMPLE 3 controls the surface charge of the magaldrate to create a desirable negative in?uence while the ?rst ?uidizer apparently enhances the anion adsorption process a 25 Ingredients Amount (mg) provides a competitive substrate with the magaldrate Magaldrate Gel 201.3 thereby maintaining an equilibrium of the negative in Aluminum Hydroxide (colloidal) 10.5 fluence. The negative in?uence, which can be deter Potassium Citrate 40.1 Saccharin 0.4 mined by zeta potential measurements, thus fluidizes the Sorbitol Solution (70%) 80.0 magaldrate suspension to a mobilizable gel having an Glycerine 20.0 equilibrium which apparently provides for retention of Lemon Flavor 2.7 desirable'properties. Peppermint Flavor 0.2 The invention may be further illustrated by the fol Water q.s. 1000.0 lowing examples. In example 1-3 the magaldrate gel (potassium base) was ?rst concentrated to about a 24% The approximate ANC of this 20.1% w/w magal w/w strength at which point it was a stiff immobile drate is about 29 meq/ 5 ml. paste and then used to prepare the composition listed. The composition of this example again provided a ?uid suspension and was prepared as described in Ex EXAMPLE 1 ample 1 with the same results. EXAMPLE 4 Ingredients Amount (mg) A magaldrate suspension product, according to the Magaldrate Gel 152.5 invention, having an ANC of 30 meq/S ml or magal Aluminum Hydroxide (colloidal) 7.4 Potassium Citrate 30.8 drate 1080 mg/5 ml of suspension was prepared as fol Saccharin 0.4 45 lows. The formula given is for 1 liter (1.18 Kg). Sorbitol Solution (70%) 100.0 Peppennint Flavor 0.2 Orange Flavor 2.0 Ingredient Amount Water q.s. 1000.0 Magaldrate Gel 2.93 1" Aluminum Hydroxide Gel (12.5% A1203) 47.8 g 50' Potassium Citrate 19.6 g This composition provided a magaldrate suspension Sorbitol Solution (70%) 57.4 g according to the invention having 15.2% magaldrate Glycerin 47.8 g solids providing approximately 20 meq/S ml of ANC. Saccharin 0.383 g The citrate was dissolved in sufficient water to make Xanthan Gum 1.43 g Peppermint, Natural and Arti?cial 0.283 ml an 80% w/w solution. The citrate solution and the 55 Monochlorarnine Solution q.s. aluminum hydroxide which is provided as a paste Water, puri?ed, Chlorinated q.s. 1.18 Kg. (12.5—13.5% A1203) were added to the concentrated ‘Theoretical input per liter is 216 g Magaldrate at 100% magaldrate gel paste. The mixture was blended until it became a mobile liquid suspension. The other ingredi 1. In a suitable tank equipped with a mixer, the sorbi ents were then added to the suspension, the water being 60 tol solution, 15.7 g of the water and the citrate were last to provide the ?nal weight. The mixture was further combined and then mixed until a clean solution was blended to yield a homogeneous suspension. The ?nal obtained. The aluminum hydroxide gel was added and suspension was then further homogenized prior to ?ll mixed until uniform and mixing continued until use. ing the palatable suspension into 12 ?uid ounce con 2. Immediately before concentration of the magal tainer for stability observation. 65 drate gel, 126 g of the Step #1 mixture was added to a The suspension was evaluated over a four month jacketed tank equipped with a stirrer. With continuous period. At each time point, the suspension was found to stirring, the magaldrate gel was concentrated on a ro have maintained its initial ANC, physical appearance, tary ?lter to a concentration of not less than 24% w/w 4,704,278 9 10 into the mixture and cooling to 25° C. was begun. After -continued all the concentrated had been added the remainder of Amount the Step #1 mixture was added with continuous stirring Ingredient A B to achieve uniformity. Glycerin 95.6 g 3. The Step #2 mixture was poured through a ho Saccharin .766 g mogenizer into a jacketed tank with continuous stirring Xanthan Gum 2.86 3.43 g and continuous cooling to 25° C. Peppermint Flavor 0.57 ml Monochloramine Solution q.s. 100 ppm 4. The remaining ingredients, except the water and Water, distilled q.s. 2.321 Kg monochloramine, were mixed in a separate container until uniform, after which, they are added to the magal In this experiment, two different freshly concentrated drate mixture and mixed until the xanthan gum was magaldrate gels at the percents indicated were em hydrated. Water was then added (with mixing) to bring ‘ ployed to prepare suspensions with an ANC of 30 the batch up to about 1.18 Kg. meq/S ml. The sorbitol, citrate, and aluminum hydrox .5. Prior to ?lling the suspension, suf?cient mono ide gel were added to a container equipped with a stir chloramine was added to and mixed into the bulk mate rer and mixing was begun. The magaldrate was added rial to provide at least 85 ppm in the suspension. to the same container, preferrably incrementally and 6. The suspension was then ?lled into sterilized con mixed until uniform. The saccharin and flavor were tainers which were capped, inverted and returned to the dispensed in the glycerin, after which, the xanthan gum upright position. 20 was added and mixed until uniform. The ?avored dis The suspension of this example was subjected to re pension was then added to the ?uidized magaldrate peated freeze~thaw cycles of 24 hours each, and after " with mixing until the mixture was uniform and the gum each cycle both the physical and antacid properties hydrated. Suf?cient distilled water was added with mixing as was a quantity of the chlorine sanitizing solu were retained. In contrast, a conventional magaldrate 25 tion to provide about 100 ppm chlorine. The suspen suspension at even 13.5 meq/S ml with acacia as the sions (12) having an aluminum oxide ratio to citrate de?occulant did not retain all the properties after only ranging from about 1:88 to about 13.95 were then ?lled one such cycle. into container. All formulations provided suspensions with the desired physical and antacid properties includ EXAMPLE 5 ing resuspendibility. Using the procedure described in Example 4, a ma galdrate suspension, according to the invention, having EXAMPLE 8 an ANC of about 45 meq/S ml may be prepared. A typical formulation for the monochloramine solu tion referred to in some of the prior examples as follows: 35 Calcium Hypochlorite 60%: 14.0 g Ingredients Amount Ammonia Solution, Strong: 7.4 g Magaldrate Gel (at about 34%) 985.0 g Water, puri?ed, chlorinated: 1998. g Aluminum Hydroxide Gel (A1203 12.5%) 47.8 g What is claimed is: Polassium Citrate 39.2 g 1. An aqueous antacid composition characterized in Sorbitol Solution (70%) 57.4 g providing a ?uid resuspendable pharmaceutically ele Glycerin 47.8 g Saccharin 0.383 g gant antacid suspension with high antacid capacity of at Xanthan Gum 1.43 g least about 25 milliequivalents of acid neutralizing ca Peppermint Flavor 0.283 ml pacity per 5 milliliters of suspension consisting essen Monochloramine Solution q.s. 100 ppm tially, prior to forming the pharmaceutically elegant Water, puri?ed, chlorinated q.s. ad 1.0 L antacid suspension, of: (a) precipitated and undried magaldrate gel contain ing at least about 24% by weight of magaldrate, EXAMPLE 6 and A magaldrate suspension, according to the invention, (b) a ?uidizing amount of a combination of (i) an was prepared with the formula and procedure described aluminum hydroxide gel having colloidal proper tiessof a ?rst ?uidizer and (ii) as a second ?uidizer in EXAMPLE 4, but for the addition of simethicone to "potassium citrate, the weight ratio on a dry basis of provide a suspension with an ANC of 30 meq/S ml and magaldrate to the combination of ?uidizers being. 30 mg/5 ml of simethicone. ._Iwithin the range of about 25:1 to 2:1 and the weight 55 EXAMPLE 7 ratio on a dry basis of the ?rst ?uidizer calculated as aluminum oxide and the second ?uidizer being within the range of about 1:6 to about 1:2. Amount 2. The composition of claim 1 wherein the ratio on a Ingredient A B 1 dry basis of magaldrate to the combination of ?uidizers ranges from about 8:1 to about 4:1. (I Magaldrate Gel at 1565 g 1789 g 27.6% w/w or 24.14% w/w/ 3. The composition of claim 1 wherein the ratio on a Aluminum Hydroxide Gel (13.5% A1203) 86.04 100.4 g dry basis of the ?rst ?uidizer to the second ?uidizer is Potassium Citrate Solution (80%) 61.9 137.6 g about 1:4. Sorbitol Solution (70%) 114.8 g * Ii * * t 65