# Patent

## Title
Stable pharmaceutical compositions, processes for making the same and methods of their use

## Abstract

The present invention is generally related to alcohol free, liquid ranitidine formulations for oral administration. In particular, the present invention is related to stable, syrup formulations having ranitidine as an active ingredient for oral administration, processes for making the same, and methods of their use. The ranitidine of the present invention is stable in non-polar media or media having a relatively low polarity such that the dielectric constant is less than about 60, and is achieved by using certain saccharides, certain relatively high molecular weight starches, and/or certain celluloses instead of alcohol.

## Background
FIELD OF THE INVENTION
The present invention is generally related to alcohol free, liquid ranitidine formulations for oral administration. In particular, the present invention is related to stable, syrup formulations having ranitidine as an active ingredient for oral administration, processes for making the same, and methods of their use.
BACKGROUND OF THE INVENTION
Ranitidine [N-[2-[[[5-(dimethylamino)methyl-2-furanyl]methyl]thio]ethyl]-N′-methyl-2-nitro-1, 1-ethenediamine] and physiologically acceptable salts thereof (having, for example, the empirical formula C13H22N4O3S—HCl and the structural Formula I shown below) are disclosed in British Patent Specification No. 1565966.




According to current prescribing information, the compound of Formula I is indicated for short-term treatment of active duodenal ulcer (most patients found to heal within 4 weeks; studies available have not assessed the safety of ranitidine in uncomplicated duodenal ulcer for periods of more than 8 weeks); maintenance therapy for duodenal ulcer patients at reduced dosage after healing of acute ulcers (no placebo-controlled comparative studies have been carried out for periods of longer than 1 year); the treatment of pathological hypersecretory conditions (e.g., Zollinger-Ellison syndrome and systemic mastocytosis); short-term treatment of active, benign gastric ulcer (most patients found to heal within 6 weeks; the usefulness of further treatment has not been demonstrated; studies available have not assessed the safety of ranitidine in uncomplicated, benign gastric ulcer for periods of more than 6 weeks); maintenance therapy for gastric ulcer patients at reduced dosage after healing for acute ulcers (placebo-controlled studies have been carried out for 1 year); treatment of GERD (symptomatic relief found to commonly occurs within 24 hours after starting therapy with 150 mg b.i.d.); treatment of endoscopically diagnosed erosive esophagitis (symptomatic relief of heartburn found to commonly occur within 24 hours of therapy initiation with 150 mg b.i.d.); and maintenance of healing of erosive esophagitis (placebo-controlled trials have been carried out for 48 weeks).
Many of the formulations containing the compound of Formula I disclosed in British Patent Specification No. 1565966 are known to be unstable and, therefore, not appropriate for marketable formulations that are required to be stable. U.S. Pat. No. 4,585,790, on the other hand, discloses improved aqueous formulations of ranitidine that are more stable. That patent discloses ranitidine formulations having a pH in the range 6.5 to 7.5 that are suitable formulations for injections for intravenous and intramuscular administration, continuous infusions, and oral preparations such as syrups. Similarly, U.S. Pat. No. 5,068,249 discloses stabile, aqueous formulations of ranitidine containing ethanol as a stabilizer. That patent describes a pharmaceutical composition which is an aqueous formulation of ranitidine and/or one or more physiologically acceptable salts thereof containing ethanol and that is suitable for administration to patients and will, in general, contain at least one conventional pharmaceutical excipient in addition to the ethanol and ranitidine and/or physiologically acceptable salts thereof.
U.S. Pat. No. 6,265,449 discloses an aqueous pharmaceutical composition for oral administration comprising ranitidine, or a pharmaceutically acceptable salt thereof, that contains alcohol and low color, metal, turbidity (LCMT) sucrose, which was found to improved stability, bioavailability and taste-masking of ranitidine while allowing the volume of the alcohol required in the solution to be reduced.
A commercially available version of a stable pharmaceutically acceptable salt form of the compound of Formula I is known as ZANTAC® syrup, which is described in prescribing information as being a clear peppermint-flavored liquid that contains 16.8 mg of ranitidine-HCl equivalent to 15 milligrams (mg) of ranitidine per 1 milliliter (ml) (75 mg/5 mL) in bottles of 16 fluid ounces (one pint). Because of its relative instability, ZANTAC® is usually stored between about 4° and about 25° C. (39° and 77° F.) in tight, light-resistant containers.
SUMMARY OF THE INVENTION
It has been surprisingly found that aqueous syrup formulations containing the compound of Formula I, or other physiologically acceptable salts of ranitidine, can be stabilized without the use of ethanol or other alcohols as taught in U.S. Pat. Nos. 5,068,249 and 6,265,449, and at pH ranges that are higher and lower than the ranges set forth in those patents. In particular, it has been found that ranitidine is stable in non-polar media or media having a relatively low polarity such that the dielectric constant is less than about 60, the stability achieved by using certain saccharides, starches (preferably relatively high molecular weight starches), and/or certain celluloses instead of alcohol; buffers may or may not be needed.
An advantage of the formulations of the present invention is the relatively high concentration of the saccharides that help mask the taste of ranitidine.
Another advantage of the formulations of the present invention is that non-alcoholic aqueous formulations are generally preferred by, among others, parents who administer those formulations to their children.
Thus, the present invention involves a pharmaceutical composition which is an aqueous formulation containing a pharmaceutically effective amount of ranitidine and/or one or more physiologically acceptable salts thereof for treatment of conditions mediated through histamine H2-receptors, the formulation having a pH preferably within the range of about 4.85 to about 7.99, and most preferably within the range of about 6.5 to about 7.5, making it suitable for administration to humans and other mammals.


DETAILED DESCRIPTION OF THE INVENTION
The present invention involves a pharmaceutical composition of the compound of Formula I, or other physiologically acceptable salts of ranitidine, that is stable when dissolved in or combined with one or more saccharides, one or more starches (preferably relatively high molecular weight starches), and/or celluloses as stabilizers. In addition, physiologically acceptable carriers, excipients, diluents, colorants, flavorants, and other substances may also be added.
The preferred saccharides of the present invention include, but are not limited to, inverse sugar, dextrose, glucose, trehalose, lycasin (70% corn syrup), cyclodextrins, niacinamide, dextran, and other mono-, oligo- and poly-saccharides.
The preferred starches of the present invention include, but are not limited to, maize starch, potato starch, pregelatinized starch, topiaco and hydroxyl ethyl starch (HES). Cyclodextrins, which are cyclic carbohydrates derived from starch, are also contemplated as part of the invention for use in the stable compositions of ranitidine hydrochloride.
The preferred cellulose of the present invention include, but is not limited to, hydroxyl propyl cellulose (HPC), hydroxy propyl methyl cellulose (HPMC), and hydroxyl ethyl cellulose (HEC).
The concentration of the stabilizers preferably varies from about 5% to about 80% volume per total final composition, preferably from about 40% to about 70% volume per total final composition, most preferably about 5%, especially in the case of cellulose.
The concentration of the compound of Formula I is preferably about 16.8 mg/ml.
Stable pharmaceutical formulations of ranitidine hydrochloride using PVP and niacinamide are also contemplated.
Excipients include those that are suitable for the manufacture of aqueous suspensions and include, but are not limited to suspending agents, dispersing or wetting agents, preservatives, coloring agents, flavoring agents, and sweetening agents.
Stabilization of the ranitidine in the present invention is accomplished by, for example, reducing the dielectric constant of water. Water is a very polar medium and ranitidine, being a polar molecule, effectively degrades in water. By reducing the dielectric constant of the medium in which ranitidine will come in contact with, or by reducing the water activity at the reaction site, the stability of the ranitidine may be increased, which is to say that the degradation potential may be reduced.
The hydrolytic degradation reaction involving ranitidine is essentially as follows:




Previous attempts to affect the degradation of ranitidine formulations focused on slowing down the rate of conversion of the ranitidine transition complex (k2) to the final degradation product. In the present invention, the stabilizers preferably reacts with water and thus reduces the water activity at the reaction site. That, in turn, slows down the rate of formation of the transition complex (k1), which controls the overall degradation of the ranitidine.
It has been found that buffering may or may not be needed with the formulations of the present invention. If a buffer is used, the buffer can be, but is not limited to, acetate, citrate, phosphate, succinate, or any pharmaceutically acceptable acid or base with pKa ranging 4.5 to 6.5. The preferred buffer includes citric acid and disodium hydrogen orthophosphate, or potassium dihydrogen phosphate and disodium hydrogen phosphate.
Formulations of the present invention may be prepared by combining, in an appropriate sequence, an amount of the compound of Formula I, or other physiologically acceptable salts of ranitidine, with one or more saccharides or high molecular weight starches, and with one or more physiologically acceptable carriers, excipients, diluents, colorants, flavorants, or other substances, whereby the compound of Formula I is combined with the one or more saccharides or one or more high molecular weight starches, or one or more celluloses in order to achieve a generally stabilizing effect on the ranitidine. The resulting ranitidine concentration is about 15 mg/ml of free base (ranitidine plus water), preferably 16.8 mg/ml of free base.
The formulations of the invention may be made according to the following process. First, potable water, e.g. 40 mL, is transferred into a beaker calibrated to a predetermined batch volume, e.g. 50 ml. An amount of raniditine is added to the water to make a solution having a desired concentration, e.g. about 16.8 mg/ml. Into that solution, a sufficient amount of a buffer is dissolved to obtain a target pH, e.g. about 4.85 to about 7.99, preferably about 6.5 to about 7.5. Next, a stabilizer, such as one or more saccharides, and/or high molecular weight starches, and/or HPC or other cellulose, is/are admixed with the water/ranitidine/buffer solution in an amount necessary to stabilize the raniditine. An amount of potable water is then added to fill to the predetermined batch volume.
In addition to the above components, one or more excipients may be added to the solution along with the stabilizing agent.
Without further description, it is believed that one of ordinary skill in the art can, using the preceding description and the following illustrative examples, make and utilize the compounds of the present invention and practice the methods. The following examples are given to illustrate the present invention. It should be understood that the invention is not to be limited to the specific conditions or details described in these examples.
EXAMPLE 1
The formulations of the invention are made according to the following process. First, 40 ml of potable water are transferred into a beaker calibrated to a batch volume of 50 ml. An amount of ranitidine is added to the water to make a solution having a concentration of about 16.8 mg/ml. Into that solution, a sufficient amount of a buffer is dissolved to obtain desired pH. In some occasions. 0.1N NaOH was also used to adjust the pH in addition to buffer to get the target pH. Next, a stabilizing agent such as one or more saccharides and/or high molecular weight starches is/are admixed with the water/ranitidine/buffer solution in an amount necessary to stabilize the ranitidine. An amount of potable water is then added to create a batch volume of 50 ml. Samples of the resulting composition are introduced into 5-ml flint stopper vials for accelerated stability tests.
In addition to the above components, one or more excipients may be added to the solution along with the stabilizing agent.
EXAMPLE 2
Compositions and pharmaceutical compositions containing ranitidine hydrochloride are shown in Table 1 below.











TABLE 1







LOT





NO
FORMULATION
PH




















RNT-2
Drug- 16.8 mg/ml
6.81



(Control)
KH2PO4 1.0 mg/ml




K2HPO4 2.4 mg/ml




Ethanol 7.5%




Water - q.s. to target volume



RNT-9
Drug 16.8 mg/ml,
5.6




Dextran- 10%




KH2PO4 3.0 mg/ml




K2HPO4 1.0 mg/ml




Corn syrup 16%




Water q.s. to target volume



RNT-10
Drug 16.8,
6.81




Dextran- 10%




KH2PO4 1.0 mg/ml




K2HPO4 2.4 mg/ml




Corn syrup 16%




Water q.s. to target volume



RNT-11
Drug 16.8 mg/ml
7.85




Dextran - 10%




Corn syrup 16%




KH2PO4 1.0 mg/ml




K2HPO4 2.4 mg/ml




pH adj. With 0.1N




Water q.s. to target volume



RNT-13
Drug 16.8 mg/ml
7.02




HydroxyEthyl Starch 10%




Corn syrup 16%




KH2PO4 1.0 mg/ml




K2HPO4 2.4 mg/ml




pH adj. with 0.1N NaOH




Water q.s. to target volume



RNT-14
Drug 16.8 mg/ml
7.83




Hydroxyethyl Starch - 10%




Corn syrup 16%




KH2PO4 1.0 mg/ml




K2HPO4 4.0 mg/ml




Water q.s. to target volume



RNT-20
Drug 16.8 mg/ml
5.22




Alcohol 7.5% (v/v)




No pH adjustment




Water q.s. to target volume



RNT-21
Drug 16.8 mg/ml
7.2




Alcohol 7.5% (v/v)




KH2PO4 1.0 mg/ml




K2HPO4 3.0 mg/ml




Water q.s. to target volume










EXAMPLE 3
Eight pharmaceutical compositions containing ranitidine hydrochloride were prepared according to the formulations shown in Table 2. Two-week and/or four-week stability tests were conducted at 40° C. on each formulation with assays of ranitidine-HCl being conducted initially at the start of each test and at the end of the two week and/or four week test period. The results of the tests are shown in Table 2.









TABLE 2









STABILITY ANALYSIS



(ASSAY OF RANITIDINE



HCL)
















2 WKS
4 WKS


LOT



AT
AT


NO
FORMULATION
PH
INITIAL
40° C.
40° C.















RNT-
Drug 16.8 mg/ml
5.6
100%

106%


12
Starch 10%



corn syrup 16%



KH2PO4 3 mg/ml



Na2HPO4 1 mg/ml



Water qs to 1 ml


RNT-
Drug 16.8 mg/ml
7.85
100%

102%


14
HES 10%



corn syrup 16%



KH2PO4 1 mg/ml



Na2HPO4 4 mg/ml



Water qs to 1 ml


RNT-
Drug 16.8 mg/ml
5.22
100
99
98


20
Alcohol 7.5% (v/v)



No pH adustment



Water qs to target



volume


RNT-
Drug 16.8 mg/ml
7.2
100
99
96


21
Alcohol 7.5% (v/v)



KH2PO4 1 mg/ml



Na2HPO4 3 mg/ml



Water qs to target



volume


RNT-
Drug 16.8 mg/ml HPBCD
7.99
100%
96%


31
1.5 mg/ml



Niacinamide 3 mg/ml



pH adjusted with 0.1N



NaoH


RNT-
Drug 16.8 mg/ml
5.5
100
98
97


32
HPBCD 1.5 mg/ml



Niacinamide 3 mg/ml



HES 100 mg/ml



KH2PO4 3 mg/ml



Na2HPO4 1 mg/ml



Water qs to 1 ml


RNT-
Drug 16.8 mg/ml
7.83
100
NP
93


51
Niacinamide 10 mg/ml



pH adjusted with 0.1N



NaOH



Water qs to 1 ml


RNT-
Drug 16.8 mg/ml
7.84
100
NP
102 


53
PVPK 10 mg/ml



KH2PO4 1 mg/ml



Na2HPO4 mg/ml



pH adjusted with 0.1N



NaOH



Water qs to 1 ml









EXAMPLE 4
We have also formulated ranitidine with hyrdoxypropyl cellulose (HPC). Hydroxypropyl cellulose is used as a binder in the granulation step of tablet dosage form development. It has high affinity for water. Hence, it was theorized that the HPC is extensively hydrated by water thereby reduces the activity of water at the reaction site. A formulation, RNT-42, comprising ranitidine 16.8 mg/ml, hydroxypropyl cellulose 5%, KH2PO4 3 mg/ml, Na2HPO4 1 mg/ml., pH adjusted to 5.8 was prepared and its stability along with the simulated ranitidine syrup (innovator formulation) was evaluated. The samples ware assayed by the USP monograph method. The stability data is summarized in TABLE 4.







TABLE 4







STABILITY ASSAY OF RNT-42 at 40° C.










DAYS
ASSAY (% of target)







INITIAL
103%



30 DAYS
102%



60 DAYS
103%



90 DAYS
 99%







Target: 16.8 mg/ml ranitidine HCl






The impurity samples were taken at different time periods and were assayed by using a HPLC method described under ranitidine monograph in Pharm. Eur. Impurities B, C, E and G are identified as know impurities in the monograph. RRT means relative retention time of degradation peaks with reference to ranitidine peak. The impurities are summarized in TABLES 5-6.







TABLE 5







IMPURITY AT 40° C. OF RNT-42

















Name of the



DAYS
RRT
Area %
Area
impurity

















30
0.27
0.11
3010
Unknown




0.57
0.06
1690
Unknown




0.58
0.06
1794
C




0.62
0.13
3662
Unknown




0.85
0.17
4929
Unknown



60
0.28
0.10
2395
Unknown




0.55
0.21
4846
Unknown




0.60
0.09
2213
C




0.70
0.08
1775
E




0.86
0.44
10359
Unknown




1.16
0.16
3764
Unknown



90
0.22
0.20
4237
Unknown




0.28
0.13
2818
Unknown




0.50
0.14
2915
B




0.57
0.14
2942
C




0.82
0.51
10550
Unknown

















TABLE 6







IMPURITY AT 25° C. OF RNT-42



















Name








of the



S.No.
DAYS
RRT
Area %
Area
Impurity







1
90
0.22
0.057
1217
Un known





0.50
0.083
1795
B





0.57
0.090
1945
C










EXAMPLE 5
The following composition (RNT-57) was prepared and assayed for stability and impurity: drug (ranitidine), 2.5% HPC, 5% HES, niacinamide 1.5 mg/ml, cyclodextrin 1.5 mg/ml, and buffers (pH adjusted 5.7).







TABLE 7







STABILTIY ASSAY OF RNT-57










DAYS
ASSAY (% of target)







INITIAL
113



30 DAYS
111



60 DAYS
102










Target concentration: 16.8 mg/ml








TABLE 8







IMPURITY AT 40° C. OF RNT-57

















Name of the



DAYS
RRT
Area %
Area
impurity

















Initial
0.28
0.09
2356
Unknown




0.60
0.07
1803
C




1.16
0.09
2350
Unknown



30
0.28
0.12
3039
Unknown




0.55
0.15
3795
Unknown




0.60
0.06
1570
C




0.86
0.26
6583
Unknown




1.16
1.16
3230
Unknown



60
0.12
1.24
29600
Unknown




0.18
2.74
65566
G




0.26
0.17
3985
Unknown




0.84
0.50
11944
Unknown










EXAMPLE 6
The following composition (RNT-58) was prepared and assayed for stability and impurity: drug, 2.5% HPC, 5% HES, niacinamide 1.5 mg/ml, cyclodextrin 1.5 mg/ml, and buffer (pH adjusted 7.9). RNT-58 is identical to RNT-57 in composition with exception that pH is adjusted to 7.9.







TABLE 9







STABILITY ASSAY OF RNT-58









S.NO.
DAYS
ASSAY (%)












1
INITIAL
101


2
30 DAYS
101


3
60 DAYS
89
















TABLE 10







IMPURITY AT 40° C. OF RNT-58

















Name of the



DAYS
RRT
Area %
Area
impurity

















Initial
0.28
0.06
1312
Unknown




0.60
0.06
1257
C



30
0.55
0.16
3753
Unknown




0.60
0.13
2919
C




0.85
0.34
7669
Unknown




1.16
0.07
1495
Unknown



60
0.20
4.35
113447
G




0.85
0.89
22818
Unknown










EXAMPLE 7
The following TABLES 10 and 11 compares the stability and impurities of the commercially available formulation (RNT-02) with RNT-42. RNT-02 is simulated version of commercially available formulation without flavor and preservatives. RNT-02 consists of the following ingredients:
















Ranitidine HCl:
16.8 mg/ml



Ethyl alcohol:
7.5% (v/v)



KH2PO4:
  1 mg/ml



K2HPO4:
 2.4 mg/ml



pH adjusted:
7.0

















TABLE 10







STABILITY COMPARISON











Potency
Potency
Potency


Formulation
1 month (%)
2 months (%)
3 months (%)





RNT-42
100
98
98


Lead Formulation


Control
100
97
96


RNT-02
















TABLE 11







IMPURITY COMPARISON











30 DAYS
60 DAYS
90 DAYS



Related Substances
Related Substances
Related Substances
















LOT#
Impurity
% Area
RRT
Impurity
% Area
RRT
Impurity
% Area
RRT





RNT-
Unknown
0.11
0.28
Unknown
0.10
0.28
Unknown
0.20
0.22


42
Unknown
0.06
0.57
Unknown
0.21
0.55
Unknown
0.13
0.28



Unknown
0.06
0.58
C
0.09
0.60
B
0.14
0.50



C
0.13
0.62
E
0.08
0.70
C
0.14
0.57



Unknown
0.17
0.85
Unknown
0.44
0.86
Unknown
0.51
0.82






Unknown
0.16
1.16





Total
0.53

Total
1.08

Total
1.12


RNT-
Unknown
0.33
0.33
Unknown
0.14
0.18
Unknown
0.49
0.55


02
C
0.17
0.59
Unknown
0.17
0.44
C
0.47
0.60


Control
Unknown
0.33
0.81
C
0.29
0.59
E
0.13
0.70






Unknown
0.47
0.81
Unknown
0.86
0.86



Total
0.83

Total
1.07

Total
1.95









As shown above, the alcohol free formulation showed good stability at 40° C. as only 2% loss observed at over 3-month storage. Also, total impurities formed in the alcohol free formulation are lower than that of the simulated innovator formulation. Based on this data we can project a shelf life of 3 years under ambient storage conditions. There are quite a few impurities greater than 0.1%. However, the degradation products observed under accelerated conditions may not necessarily form under ambient storage condition. The stability at 3 months at 25° C. showed only one impurity peak.
EXAMPLE 8
The following composition (RNT-R1) was prepared and assayed for stability and impurity: drug 16.8 mg/mL and HPC 50.0 mg/mL (pH adjusted 5.73 with 0.1N sodium hydroxide).







TABLE 12







Stability of RNT-R1 at 40° C.













STABILITY


IMP.



TIME
(%)
IMP. (%)
RRT
NAME
pH













Initial
100
Impurities not detected
5.73












30 Days
97.9
0.07
0.60
C
6.00




0.27
0.88
UK









Total impurities
0.34













60 Days
96.8
0.38
0.26
UK
6.32




0.14
0.55
UK




0.18
0.60
C




0.42
0.88
UK




0.26
1.27
UK









Total impurities
1.38













90 Days
95.5
0.42
0.26
UK





0.33
0.46
UK




0.17
0.55
UK




0.24
0.60
C




0.54
0.88
UK




0.14
1.24
UK









Total impurities
1.84





UK—unknown


IMP—impurity













TABLE 13







Stability of RNT-R1 at 25° C.












TIME
STABILITY






(HRS)
(%)
IMP. %
RRT
IMP. NAME
pH













INITIAL
100.0
NOT DETECTED
5.73












 90 DAYS
99.1
0.04
0.88
UK
5.54


180 DAYS
99.0
0.06
0.88
UK
5.82









The accelerated stability of RNT-R1 showed comparable impurity profile compared to the pilot formulation (RNT-42).
EXAMPLE 9
In the next study, we studied the stability of RNT-R1 in the presence of sweetener and preservative. The formulation composition and stability data presented below:










Composition (RNT-R2)



















Drug:
16.8
mg/ml



HPC:
50.0
mg/ml



Sodium saccharin:
3.0
mg/ml



Methylparaben-Na (MPS):
0.7
mg/ml



Propylparaben-Na: (PPS):
0.2
mg/ml



pH adjusted with 0.1N NaOH:
5.69

















TABLE 14







STABILITY AND IMPURITIES OF RNT-R2 AT 40° C.












TIME
STABILITY


IMP



(HRS)
(%)
IMP. %
RRT
NAME
pH













INITIAL
100.0
NOT DETECTED
5.73












30 DAYS
98.2
0.27
0.88
UK
6.01









Total impurities
0.27













60 DAYS
97.1
0.19
0.27
UK
6.33




0.23
0.45
UK




0.52
0.88
UK









Total impurities
0.94













90 DAYS
96.4
0.23
0.26
UK
6.32




0.17
0.45
UK




0.69
0.88
UK









Total impurities
1.09









The stability of RNT-R2 appears to be better than that of RNT-R1. The number of impurity peaks limited to three and total peak are is around 1.1% compared to 1.84% for the RNT-R1. The pH of the syrup at the end of 3 months is also below 6.5.







TABLE 15







STABILITY AND IMPURITIES OF RNT-R2 AT 25° C.












TIME
STABILITY






(HRS)
(%)
IMP. %
RRT
IMP NAME
pH













INITIAL
100.0
IMPURITIES NOT DETECTED
5.73












 90 Days
99.0
0.05
0.83
UK
6.01


180 Days
99
0.07
0.83
UK
6.26









EXAMPLE 10
In the next set of experiment, we tested the stability of RNT-R2 in the presence of buffer at pH 7.8. The purpose of this experiment is to determine the effect of weakly alkaline pH condition on the stability of ranitidine. The composition (RNT-R3) and the stability is presented below.
Composition (RNT-R3):

















Drug
16.8
mg/ml



HPC
50.0
mg/ml



KH2PO4
1.0
mg/ml



Na2HPO4
4.0
mg/ml



Sodium Saccharin
3.0
mg/ml



MPS
0.7
mg/ml



PPS
0.2
mg/ml



pH
7.79

















TABLE 16







STABILITY AND IMPURITIES OF RNT-R3 AT 40° C.












TIME







(HRS)
ASSAY (%)
IMP. %
RRT
IMP NAME
pH













INITIAL
100.0
Impurities not detected
7.84












30 Days
96.9
0.35
0.58
C
7.78




0.31
0.88
J









Total Impurities
0.66













60 Days
94.2
0.12
0.11
H
7.42




0.06
0.53
UK




0.18
0.56
UK




0.12
0.72
E




0.68
0.83
UK




0.08
1.27
UK




0.30
1.32
I




0.40
1.61
UK




0.39
1.69
A









Total Impurities
2.33













90 Days
91.3
0.16
0.11
H
7.45




0.05
0.51
B




0.21
0.55
UK




0.13
0.72
E




0.83
0.83
UK




0.31
1.27
UK




0.40
1.35
UK




0.25
1.64
UK









Total Impurities
2.34









As shown in the table, the alkaline conditions have adverse effect on the stability of ranitidine syrup and also observed late eluting degradation products.







TABLE 17







STABILITY OF RNT-R3 AT 25° C.
















IMP



TIME (HRS)
ASSAY (%)
IMP. %
RRT
NAME
pH













INITIAL
100.0
NOT DETECTED
7.84












90 DAYS
97.1
0.04
0.83
UK
7.41




0.08
1.65
UK









TOTAL IMPURITES
0.12









Even at room temperature we observed 3% degradation suggesting that the HPC containing ranitidine syrup is not as stable under neutral to weakly alkaline conditions. The HPC containing formulation showed better stability under weakly acidic condition.
EXAMPLE 11
In the next set of experiments we studied the stability of RHT-R2 in the presence Xylitol (RNT-R5) and Xylitol plus flavoring agent (mint oil) (RNT-R6). We have conducted these trials in triplicate, i.e., three batches were made per lot. The data presented here is the mean of the three batches. The syrup was stored in PET bottles. The compositions and the stability data presented below.
Composition (RNT-R5):

















Drug
16.8
mg/ml



HPC
50.0
mg/ml



Xylitol
50.0
mg/ml



Sodium Saccharin
3.0
mg/ml



MPS
0.5
mg/ml



PPS
0.05
mg/ml



pH
5.55

















TABLE 17







STABILITY AND IMPURITIES OF RNT-R5 AT 40° C.
















Imp



TIME (HRS)
ASSAY (%)
IMP. %
RRT
name
pH













INITIAL
100.0
NOT DETECTED
5.55












30 DAYS
97.3
0.45
0.23
UK
5.65




0.26
0.45
UK




0.08
0.53
UK




0.37
0.82
D




0.21
1.23
UK









TOTAL IMPURITIES
1.37









Composition (RNT-R6):


















Drug
16.8
mg/ml



HPC
50.0
mg/ml



Xylitol
50.0
mg/ml



Sodium Saccharin
3.0
mg/ml



MPS
0.5
mg/ml



PPS
0.05
mg/ml



Pippermint
0.001
mg/ml



pH
5.81

















TABLE 18







STABILITY AND IMPURITIES OF RNT-R6 AT 40° C.














TIME
ASSAY


Imp




(HRS)
(%)
IMP. %
RRT
name
pH
















INITIAL
100.0
NOT DETECTED
5.81














30 DAYS
97.5
0.22
0.23
UK
6.15





0.13
0.45
UK





0.05
0.53
UK





0.09
0.82
D





0.21
1.23
UK





0.15
1.36
UK












TOTAL IMPURITIES

0.85










EXAMPLE 12
Based on the stability data of the pilot batches, RNT-R2 had been chosen for further development. Several taste masking studies have been conducted; and it was found that the combination of RNT-R2 with raspberry flavor, orange flavor and peppermint flavor has provided a taste-masked formulation. The composition of the formulation is given below:
Composition of Flavored RNT-R2:
















Drug
16.8 mg/ml 



HPC
50.0 mg/ml 



Sodium Saccharin
3.0 mg/ml



MPS
0.7 mg/ml



PPS
0.2 mg/ml



Pippermint flavor
0.4% (v/v)



Orange flavor
2.0% (v/v)



Raspberry flavor
2.0% (v/v)



pH
5.69










Although certain presently preferred embodiments of the invention have been specifically described herein, it will be apparent to those skilled in the art to which the invention pertains that variations and modifications of the various embodiments shown and described herein may be made without departing from the spirit and scope of the invention. Accordingly, it is intended that the invention be limited only to the extent required by the appended claims and the applicable rules of law.
An alcohol-free aqueous pharmaceutical composition for oral administration comprising ranitidine and/or one or more physiologically acceptable salts thereof with a stabilizing effective amount of a cellulose, a starch, or a saccharide, wherein the composition has a pH in the range of about 4.85 to about 7.99.

## Claims

1. An alcohol-free aqueous pharmaceutical composition for oral administration comprising ranitidine or a physiologically acceptable salt thereof, and about 1-5% (weight/volume) hydroxyethyl starch as a stabilizer, wherein the composition has a pH in the range of about 4.85 to about 7.99.

2. The composition of claim 1, containing about 5% of the stabilizer.

3. The composition of claim 1, wherein the pH is about 5.5 to 7.5.

4. The composition of claim 1, wherein the pH is obtained without the use of buffer salts.

5. The composition of claim 1, wherein the ranitidine concentration is about 16.8 milligrams per milliliter dose.

6. The composition of claim 1, further comprising a sweetening agent, a buffer, or a flavoring agent.

7. The composition of claim 6, wherein the sweetening agent is saccharin.

8. The composition of claim 6, wherein the flavoring agent is selected from the group consisting of peppermint, orange, raspberry, and combinations thereof.

9. The composition of claim 6, wherein the buffer comprises acetate, citrate, phosphate, succinate, or a pharmaceutically acceptable acid or base with pKa of about 4.5 to 6.5.

10. The composition of claim 6, further comprising methyl paraben sodium or propyl paraben sodium.

11. The composition of claim 10, wherein the concentration of methyl paraben sodium is about 0.7 mg/mL and the concentration of propyl paraben sodium is about 0.2 mg/mL.

12. The composition of claim 1, wherein the composition is at least 95% stable after 90 days at 40° C.

13. A method for stabilizing an aqueous alcohol-free ranitidine solution comprising the steps of:
a) providing the aqueous solution of alcohol-free ranitidine or of a salt thereof;
b) adding to the aqueous solution about 1-5% hydroxyethyl starch as a stabilizer; and
c) adjusting the pH to about 4.85 to about 7.99.

14. The method of claim 13, wherein about 5% of the stabilizer is added to the aqueous solution.

15. The method of claim 13, wherein the pH is about 5.5 to 7.5.

16. The method of claim 13, wherein the pH is obtained without the use of buffer salts.

17. The method of claim 13, wherein the final ranitidine concentration is about 16.8 mg per mL dose.

18. The method of claim 13, further comprising the step of adding a sweetening agent, a buffer, or a flavoring agent.

19. The method of claim 18, wherein the sweetening agent is saccharin.

20. The method of claim 18, wherein the flavoring agent is selected from the group consisting of peppermint, orange, raspberry, and combinations thereof.