Background of the Invention

Aspirin and acetaminophen (also referred to as paracetamol and APAP, respectively) are well-known analgesic and antipyretic agents. They are often employed with caffeine.

Buffered aspirin products that are formulated to simultaneously deliver alkaline material and aspirin to the stomach are known in the art. The alkaline material is co-administered with aspirin to reduce the acidity of the stomach content and to react with the aspirin to form a soluble salt thereof.

In the co-administration of tablets containing alkaline material(s) and aspirin, it is customary to separate the alkaline material(s) from the aspirin. One way to accomplish this is through the formulation of a multi-layer tablet in which the alkaline material(s) is (are) contained in one layer and the aspirin in another layer.

U.S. Patent 4,664,915 ('915 patent) discloses that in multi-layered compressed tablets the rate of reaction of the alkaline material with the acid content of the stomach can be increased if the tablets contain citric acid and monobasic sodium phosphate as part of the alkaline layer. As is evident from Claim 1 of the '915 patent, the alkaline component is selected from the group consisting of calcium carbonate, magnesium carbonate, a magnesium-oxy component and mixtures thereof. The magnesium-oxy component is selected from the group consisting of magnesium oxide, magnesium hydroxide, and combinations thereof.

Grattan et al., "A five way crossover human volunteer study to compare the pharmacokinetics of paracetamol following oral administration of two commercially available paracetamol tablets and three development tablets containing paracetamol in

combination with sodium bicarbonate or calcium bicarbonate", Eur. J. Pharm Biopharm. 2000, 43 (3), 225-229), report that, in a panel of 15 fasted volunteers, paracetamol was absorbed faster from tablets containing 630 mg sodium bicarbonate than from conventional paracetamol tablets.

Rostami-Hodjegan et al., Drag Development and Industrial Pharmacy, 28 (5), 523-531 (2002)), report that, as indicated by a shorter t _max in both the fed and fasted state and a higher C _max in the fasted state, as compared to conventional tablets, paracetamol is absorbed more rapidly from the tablets containing sodium bicarbonate. The two formulations were deemed bio-equivalent with respect to area under the curve (AUC). As indicated by AUC, food did not affect the extent of absorption from either formulation. However, as indicated by the longer T _max and C _max , food reduced the rate of absorption from both formulations.

Rostami-Hodjegan et al. refer to the work of Neilsen et al., "Analgesic Efficacy of Immediate and Sustained Paracetemol and Plasma Concentration of Paracetamol, Double Blind, Placebo Controlled Evaluation Using Painful Laser Stimulation", Eur. J. Clin. Pharmacol. 1992, 42, 261-264, who postulate that the rate of increase in paracetamol plasma concentration may be important in the alleviation of acute (laser-induced) pain.

Rostami-Hodjegan et al. also refer to Luthy et al., "The Analgesic Effect of Paracetamol Depends on Its Method of Administration" Scweiz. Med. Wochenschr. 1993, 123 (50/11), 406), who conclude that only rapid administration of paracetamol produces sufficiently high plasma levels at the peak to induce effective passage of the drug to the central nervous system and cause a significant analgesic effect.

After reviewing the relevant literature, Rostami-Hodjegan et al. opine that it appears likely that the faster rate of paracetamol absorption from paracetamol/sodium bicarbonate tablets would bring the clinical benefit of a faster onset of analgesic action and possibly a greater peak analgesic effect.

Nayak et al., Journal of Pharmaco Kinetics and Biopharmaceutics (1997) 5 (6), 597-613, studied the in-vitro dissolution profile, in- vitro and in-vivo buffering characteristics, and single dose bioavailability, of various buffered aspirin tablet formulations. Buffering agents, such as magnesium and aluminum hydroxides or magnesium carbonate and aluminum glycinate, were found to significantly increase the rate of aspirin dissolution from solid dosage forms, as compared to an unbuffered tablet formulation. The extent of aspirin absorption was equivalent with all formulations; however, the faster rate of dissolution (t50 and t90) with buffered formulations resulted in earlier and higher peak concentration of salicylate, as compared to that obtained with the unbuffered formulation.

Grattan et al., European Journal of Pharmaceutics and Biopharmaceutics (2000 May), 49 (3), 225-9, carried out a five-way crossover human volunteer study to compare the pharmacokinetics of paracetamol following oral administration of two commercially available paracetamol tablets and three development tablets containing paracetamol in combination with sodium bicarbonate or calcium carbonate. The results demonstrated that the addition of 630 mg of sodium bicarbonate to paracetamol tablets increased the rate of absorption of paracetamol relative to conventional paracetamol tablets and soluble paracetamol tablets. The addition of 400 mg of sodium bicarbonate to paracetamol tablets increased the absorption rate of paracetamol relative to conventional paracetamol tablets but there was no difference in the rate of absorption compared to soluble paracetamol tablets. Grattan et al. report that, compared to the conventional paracetamol tablet, the addition of 375 mg calcium carbonate to paracetamol tablets had no effect on absorption kinetics. Grattan et al. postulate that the faster absorption observed for the sodium bicarbonate formulations could be the result of an increase in gastric emptying rate leading to faster transport of paracetamol to the small intestine where absorption takes place.

Since, as compared to the conventional paracetamol tablet, the addition of a calcium salt, for example, calcium carbonate, to paracetamol tablets had no effect on absorption kinetics, one skilled in the art would be lead away from the use of a calcium salt. The

skilled artisan would instead employ a sodium salt to increase the rate of absorption of paracetamol in paracetamol tablets.

Kelly et al, Pharmaceutical Research (2003), 20 (10), 1668-1673), compare the rates of disintegration, gastric emptying and drug absorption following administration of new and conventional paracetamol formulations. Kelly et al. conclude "it would seem that a combination of faster disintegration and gastric emptying of the new tablets [a combination of paracetamol and sodium bicarbonate] is responsible for the faster rate of absorption of paracetamol from such tablets".

Sterbenz et al., GB2103087A, disclose that, as measured by the time it takes after ingestion for the level of APAP to reach its maximum in the blood plasma of the subject to which it was administered (t _max ), the rate of absorption of APAP into the bloodstream can be increased by coadministering the APAP with about 60 mg to about 1200 mg, preferably about 400 mg to about 1000 mg, optimally about 450 mg to 880 mg of antacid. The weight of antacid used depends on its milliequivalent weight. Sterbenz et al. reference Wojcicki et al., ZbI. Pharm. 118 (1979) Vol. 2-3, who found that when 4 grams of calcium carbonate were administered with 1 gram of APAP there was a significant decrease in the rate of absorption as measure by t _max . The t _max for APAP alone was 1.4 hours. The t _max for calcium carbonate was 1.9 hours. In other words, the time it took for the plasma level of APAP to reach its maximum was 1/2 hour longer when the APAP was co-administered with the calcium carbonate than when it was administered alone. Sterbenz et al. state that when APAP is administered with the antacids at the levels called for by their invention, contrary to the teaching of Wojcicki et al., the t _max values are lower when APAP and antacid are co-administered than when APAP is administered without the antacid.

Summary of the Invention

Bristol-Myers Squibb Company markets EXCEDRIN, including EXCEDRTN MIGRAINE (under a Food and Drug Administration (FDA) approved New Drug

Application (NDA)), EXCEDRIN EXTRA STRENGH and EXCEDRIN TENSION HEADACHE. EXCEDRIN MIGRAINE tablets contain aspirin, acetaminophen and caffeine. The present inventors postulated that enhancement of the absorption of the analgesics contained in the respective tablets, for example, EXCEDRIN MIGRAINE tablets, would produce a faster onset of the analgesic/antipyretic effect produced by the tablets.

In one embodiment, the present invention produces a stable analgesic/antipyretic dosage form, for example a tablet or caplet, having enhanced absorption of the analgesic/antipyretic active(s) contained therein and faster onset of analgesic/antipyretic activity.

In a further embodiment, the invention produces a stable analgesic/antipyretic dosage form, for example a tablet or caplet, such dosage form having enhanced absorption of the analgesic/antipyretic active(s) contained therein and faster onset of analgesic/antipyretic activity while maintaining bioequivalence with the respective tablets, for example EXCEDRIN MIGRAINE tablets.

In another embodiment of the invention, an improved aspirin, acetaminophen and caffeine containing dosage form was formulated that affords faster absorption of the analgesic/antipyretic actives, as compared to an FDA approved tablet, for example, the EXCEDRTN MIGRAINE tablet, while simultaneously keeping the peak blood level (C _max ) and AUC parameters equivalent to that of the FDA approved tablets, thereby obtaining an improved faster acting product enabling suffers to obtain quicker relief.

The present inventors have surprisingly found that the inclusion of a buffer/alkaline species, for example, a carbonate, a bicarbonate or a mixture thereof, optionally with a pharmaceutically acceptable magnesium salt, in formulations containing analgesic/antipyretic actives, such as, aspirin, acetaminophen, and combinations of aspirin and/or acetaminophen, with caffeine, enhances the dissolution rate, speeds gastric emptying time, and possibly stimulates the gastro-intestinal tract, so that the

analgesic/antipyretic actives are more rapidly absorbed and the onset of the analgesic/antipyretic effect is shortened.

Detailed Description of the Invention

The composition of the present invention provides a unit dosage form containing (i) an analgesically effective amount of an analgesic/antipyretic composition comprising acetaminophen, caffeine and, optionally, aspirin and (ii) at least one pharmaceutically acceptable alkaline agent, the alkaline agent being present in an amount effective to enhance the absorption of the aspirin, acetaminophen, and/or caffeine and produce a more rapid onset of the analgesic/antipyretic effect after administration of the unit dosage form to a subject having need of pain relief or an antipyretic effect, as compared to a like unit dosage form that does not contain the alkaline agent.

The unit dosage form of the present invention contains:

(i) in one embodiment, about 25 mg to about 2.0 g acetaminophen, about 5 mg to about 500 mg caffeine, about 25 mg to about 2.5 g of at least one alkaline agent, and, optionally, about 25 mg to about 2.5 g aspirin; (ii) in another embodiment, about 100 mg to about 1 g acetaminophen, about 15 mg to about 250 mg caffeine, about 50 mg to about 1 g of at least one alkaline agent, and, optionally, about 81 mg to about 1 g aspirin; (iii) in yet another embodiment, about 150 mg to about 500 mg acetaminophen, about 30 mg to about 150 mg caffeine, about 75 mg to about 500 mg of at least one alkaline agent, and, optionally, about 150 mg to about 500 mg aspirin; and (iv) in a further embodiment, about 250 mg acetaminophen, about 65 mg caffeine, about 100 mg to about 300 mg of at least one alkaline agent, and, optionally, about 250 mg aspirin.

Examples of alkaline agents that may be employed include, but are not limited to, antacids, or a mixture of antacids, commonly employed to neutralize gastric acid, for

example calcium carbonate, magnesium carbonate, sodium bicarbonate, sodium carbonate, potassium bicarbonate, aluminum hydroxide, aluminum oxide, magnesium oxide, magnesium hydroxide, magnesium trisilicate, aluminum glycinate, dihydroxyaluminum acetate, or any mixture thereof.

In one embodiment, the alkaline agent is selected from calcium carbonate, magnesium hydroxide, magnesium carbonate, magnesium oxide, and mixtures thereof.

In another embodiment, the alkaline agent is calcium carbonate or a mixture of calcium carbonate and magnesium hydroxide

In yet another embodiment, the alkaline agent is a mixture of calcium carbonate and magnesium hydroxide.

The unit dosage form of the present invention can be a capsule (in which the alkaline agent(s) is (are) prevented from reacting with the acidic analgesic/antipyretic component(s) of the composition), a tablet or a caplet.

The unit dosage form of the present invention can also be a powder (or even an effervescent powder) which can be packaged in, for example a double pouch, in order to separate the acidic analgesic/antipyretic component(s) and alkaline agent(s).

The alkaline agent(s) can be contained in one tablet or caplet and the acidic analgesic/antipyretic component(s) can be contained in a separate tablet or caplet. The subject, generally a human, would be instructed to simultaneously or sequentially take one of each tablet or caplet.

In one embodiment, the dosage form is a tablet or caplet. In another embodiment, the dosage form is a multi-layer tablet or caplet. In yet another embodiment, the dosage form is a two-layer tablet or caplet.

Another means of keeping the acidic analgesic/antipyretic component(s) of the composition from interacting with the alkaline agent(s) is by placing the acidic analgesic/antipyretic component(s) in a capsule and inserting the capsule into another capsule containing the alkaline agent(s). Alternatively, the alkaline agent(s) can be placed in a capsule and the capsule can be inserted into another capsule containing the acidic analgesic/antipyretic component(s). The caffeine can be present in either the inner or outer capsule or apportioned between both capsules. Instead of a capsule within another capsule, the dosage form can be a tablet within a capsule or a tablet compressed within another tablet.

Yet another means of keeping the acidic analgesic/antipyretic component(s) of the composition from interacting with the alkaline agent(s) is by coating the alkaline agent(s), the acidic analgesic/antipyretic component(s) or both, so as to create a physical barrier that prevents their interaction.

The aspirin and acetaminophen are kept physically separate from the alkaline agent(s) for reasons of stability. Thus, in a further embodiment, the aspirin and acetaminophen are formulated in one layer of a multi-layer tablet or caplet and the alkaline agent(s) is (are) formulated in another layer of the multi-layer tablet or caplet. The caffeine can be formulated in either layer or divided between both layers.

The composition employed to produce the tablet or caplet dosage form of the present invention may contain other materials typically employed in such formulations, for example, excipients such as starch, dextrose, sucrose or other saccharides, sorbitol, manitol, iso-malitol, or other compressible sugar alcohols, or mixtures thereof.

In one embodiment, the composition of the present invention will also contain citric acid, sodium phosphate and starch.

The present invention will now be elaborated upon with reference to the Examples which follow and the figures in which:

Figure 1 is a graph of the plasma salicylic acid concentration, as a function of time, for Examples 1 - 4;

Figure 2 is a graph of the plasma acetaminophen concentration, as a function of time, for Examples 1 -4;

Figure 3 is a bar graph showing, for each time point, the truncated AUC values of salicylic acid for the compositions of Examples 1 - 4; and

Figure 3 is a bar graph showing, for each time point, the truncated AUC values of acetaminophen for the compositions of Examples 1 — 4.

Compositions, in accordance with the present invention, and unit dosage forms formulated therefrom, may be produced by means of pharmaceutical processing techniques well known to those skilled in the art. The acetaminophen, caffeine and, when present, the aspirin, can be formulated into tablets or caplets by means of a dry mix/direct compression approach. The alkaline agent(s) can be formulated into the tablets/caplets by means of either a dry mix/direct compression approach or a wet granulation approach.

To prevent undesirable interaction of the acetaminophen, caffeine, aspirin (when present), the alkaline agent(s) and/or excipients, the unit dosage form can be formulated, for example, as a single, bi- or triple layer tablet/caplet.

In one embodiment, a wet granulation approach can be employed utilizing a mixer or granulator, for example, a Planetary mixer, high shear granulator or fluid bed granulator. The various processing techniques would require different formula compositions and/or

different processing parameters that would be readily known or easily ascertainable by those skilled in the art.

In another embodiment, a dry mix process can be employed. In this embodiment, mixing equipment, such as, a V-blender (with or without an intensifier bar), a double-con blender, a Sigma-blade mixer, and a Tote blender, can be employed.

The embodiments which follow serve to illustrate processes that are employed in the manufacture of tablet/caplet unit dosage forms of the present invention.

In an embodiment, employing wet granulation and a high shear granulator, cold water is charged into a jacketed kettle equipped with a stirrer. Corn starch is dispersed into the cold water, and the resultant dispersion is heated in the range of 88-92°C while mixing to provide a starch paste. The resultant starch paste is cooled to a temperature of 45 - 50 ⁰ C. In a separate a PMA 300 High Shear granulator, the alkaline agent(s) and caffeine are mixed for three (3) minutes at 150 RPM with the chopper at high position. After this time, the chopper is turned off and the starch paste is gradually added to the premix in the PMA 300 High Shear granulator over a period of about ten (10) minutes. The resultant wet granulation is passed through a Comil equipped with a 500 Q screen using a round blade. The screened wet granulation is then dried in a Glatt Fluid Bed dryer, with inlet air set at 70° C and air volume at 1200 CFM, until the product temperature reaches about 42° - 46°C and the moisture content, as determined with the aid of a Mettler (program 3, temperature 105° C, using ~5 grams of sample) or Computrac Moisture Balance, is in the range of 1.2 - 2.5%. Once at the prescribed temperature and moisture content, the dry granulation is milled with the aid of a Comil (equipped with screen 075R and a round blade). After this time, the milled granulation is charged through a 10 mesh screen into a Tote blender (or V-blender) and then mixed with the excipients for five (5) minutes. At the conclusion of this period, the lubricant is charged into the blender through a 30 mesh screen, and the resulting mixture is mixed for three (3) minutes to produce the desired product.

In another embodiment, a fluid bed granulator is employed as follows: The chamber of a Glatt Fluid Bed granulator is pre-heated to 70 ⁰ C by setting the inlet air temperature to 70 °C and the air flap at 30-35%. Once at the prescribed temperature, a mix of the caffeine and alkaline agent(s) is charged into the Glatt bowl, and then, while heating the powder mix, the starch paste is sprayed into to the mix at a rate of 130-180 g/min. The granulation process is periodically checked for consistency and the spray rate and inlet air temperature are adjusted, as needed, to ensure production of a good granulation. The resulting granulation is dried in the manner set forth above and then milled at a speed of 900 rpm with the aid of a Comil, equipped with screen No. 094R. The milled dried granulation is then charged into a two (2) cubic foot Tote blender and the required amount of lubricant (previously screened through # 30 mesh) is charged into the blender. The resultant mix is blended for five (5) minutes at 24 rpm to achieve the desired product.

In another embodiment, a dry mix method is employed as follows:

(i) The caffeine, alkaline agent(s) and excipients are sequentially charged into a five (5) cubic foot Tote blender and mixed for twenty (20) minutes. After this time, the lubricant is screened through #30 mesh and then charged into the blender. The resultant mix is blended for five (5) minutes at 12 rpm to afford a caffeine/alkaline agent(s) blend.

(ii) The acetaminophen, aspirin and excipients are sequentially charged into a separate five (5) cubic foot Tote blender and mixed for twenty (20) minutes. The lubricant is added in the manner set forth in (i) above, and the resultant mix is blended for five (5) minutes at 12 rpm to afford an acetaminophen/aspirin blend.

Caplets (or tablets) are produced utilizing the blends produced in (i) and (ii) above as follows:

The acetaminophen/aspirin blend is charged into one hopper of a Two-Layer Kikusui tablet press fitted with 0.290" x 0.725" caplet shape tooling (or when tablets are desired, the appropriate tablet shape tooling). The caffeine/alkaline agent(s) blend is charged into

the other hopper. In one embodiment, the caplets (or tablets) are produced in accordance with the following specifications:

The tablet and caplet dosage forms of the present invention are optionally coated with an aqueous or solvent film coating using methods and equipment, for example, a perforated coating pan or a Fluid Bed with Wurster Column, commonly used by those skilled in the art.

In one embodiment, the film coating suspension is applied onto cores in a perforated coating pan while maintaining the following conditions:

Pan load: 12 Kg Inlet air temperature: 50-65 ⁰ C Exhaust temperature: 40-45°C Air volume: 300-350 CFM Spray rate: 40-60 g/minute Pan speed: 8-15 rpm

The coated caplets (or tablets) are then cooled to 25-30 ⁰ C. Optionally, the exhaust blower is bypassed and carnauba wax is applied to the coated caplets (or tablets) to polish their surfaces.

The following Examples are offered to illustrate the present invention and are not intended to be limiting in any respect.

Examples 1 - 4

Analgesic/Antipyretic Compositions

It should be noted that Examples 1 - 3 are illustrative of the fast acting compositions of the present invention. Example 4 is a like composition but without the alkaline agent called for by the present invention.

A preclinical pharmacokinetic (PK) study was carried out utilizing tablets prepared from the compositions of Examples 1 - 4.

A single-dose, four-sequence, four-period, four formulation, crossover Williams Design was used to differentiate the pharmacokinetic behaviors between the compositions of Examples 1 - 3 and that of Example 4. Each sequence contained two (2) naive beagle dogs. The washout period was one week. Serial blood samples were collected for a period of twelve (12) hours after oral administration. The plasma concentrations of caffeine, acetaminophen, and salicylic acid were determined using a validated HPLC method. One dog vomited in its second dosing and its' samples were not analyzed.

Pharmacokinetic values, including the time it takes for a drug to reach peak blood level (T _m a _x ) and truncated AUC, were determined by non-compartmental analysis. Analysis of variance (ANOVA) was performed on the means to determine statistical significance. The classical pharmacokinetic parameters, C _max and/or AUC, showed the compositions of Example 1 - 3 to be bioequivalent to the composition of Example 4.

In addition, a truncated AUC, reflective of plasma levels at early time points, was employed to reflect what happens during the time intervals of interest (ten (10) minutes (TlO), twenty (20) minutes (T20), and thirty (30) minutes (T30)), and indicate a faster onset of activity.

The following conclusions can be drawn from the study results:

(1) Table 1, which follows, shows the plasma level of salicylic acid in each dog in the study.

Table 1 The plasma concentrations of salicylic acid (ng/ml) 10, 20 and 30 minutes post dosing.

Cone.

SA

A H00473 H00479 H00475 H00480 H00478 H00481 H00474 HO0476 AVE SD RSD lOmin 22800 38100 17300 5120 12300 6130 9900 15000 15831 10716 68

20min 52300 41700 57800 31200 64400 57100 60100 24900 46900 28400 38

30min 59200 57400 66100 36400 75400 76500 44500 30500 60000 45100 26

B lOmin 18400 ₂ 7800 18600 11100 26300 31300 12800 20900 7726 37

20min 41700 45000 44600 30600 47300 56400 46000 44514 7670 17

30min 57400 54000 61900 38000 58200 67600 58500 56514 9207 16

C lOmin 27300 30400 24600 14400 16500 12000 11500 8660 18170 8144 45

20min 57800 60100 46900 42200 47500 38000 41200 35000 46088 8972 19

30min 66100 44500 60000 52500 60900 54000 59200 55200 56550 6535 12

D lOmin 16100 7620 4470 7720 15600 4150 6080 12100 9230 4770 52

20min 31200 24900 12100 20000 23900 12600 17300 31500 21688 7546 35

30min 36400 30500 42000 27100 28600 18700 25100 40600 31125 8014 26

In Table 1, above, A, B, C, and D respectively represent the compositions of Examples 1, 2, 3 and 4 and HO0473 to HO0476 represent dog numbers.

The results of Table 1 demonstrate that with the compositions of Examples 1 - 3 there was a faster uptake of salicylic acid in the plasma during the early time intervals post dose (10 minutes to 30 minutes), as compared to the composition of Example 4 (a like composition but without alkaline agent).

The average plasma level of salicylic acid as a function of time is shown in Figure 1.

As shown in Table 1 and Figure 1, the average level of salicylic acid in the plasma at TlO after administration of the compositions of Examples 1, 2 and 3 was 15834 ± 10716 ng/ml (Example 1), 20900 ± 7726 ng/ml (Example X), 18170 ± 8144 ng/ml (Example 3) compared to 9230 ± 4770 ng/ml (Example 4).

In other words, with the same level of aspirin being delivered from the three different compositions of the present invention, at TlO, there was about 1.5 ~ 2 times more salicylic acid present in the plasma than was present after administration of the composition of Example 4.

An ANOVA analysis showed that plasma level at TlO from the compositions of Examples 1, 2 and 3 is statistically greater than the plasma level at TlO from the composition of Example 4 (p=0.05).

As the study was crossover in design, the plasma level difference in each individual dog could be examined. It clearly showed that, as compared to dogs dosed with the composition of Example 4, 6 out of 8 dogs had a 1.5 ~ 5.5 times higher plasma salicylic acid level at TlO when dosed with the composition of Example 3. Only one dog was slightly lower.

(2) During the early time intervals post dose (10 minutes to 30 minutes post dosing), the plasma uptake of acetaminophen was faster with the compositions of Examples 1 - 3 than with the composition of Example 4.

Figure 2 shows the average plasma level of acetaminophen and Table 2, below, shows the plasma level of acetaminophen in each dog in the study.

As shown in Table 2 and Figure 2, the average plasma acetaminophen level at TlO after administration of the test compositions, was 2759 ± 2971 ng/ml (Example 1), 4461 ± 3383 ng/ml (Example 2), 4173 ± 3193 ng/ml (Example 3) and 2071 ± 1307 ng/ml (Example 4). In other words, although the same amount of acetaminophen was delivered in all of the test compositions, with the compositions of the present invention (Examples 1, 2 and 3) at TlO there was, with the compositions of Examples 2 and 3, about 2 times more acetaminophen present in the plasma (an over 200% increase), and with the composition of Example 1, an over 33% increase, as compared with the results obtained with the composition of Example 4.

As shown in Table 2, 7 out of 8 dogs had a 1.3 ~ 3.0 times higher acetaminophen plasma level at T20 with composition A (Example 1) than with composition D, with only one dog slightly lower.

Table 2. The plasma concentrations of acetaminophen (ng/ml) 10,20 and 30 minutes post dosing.

Cone.

APAP

A H00473 H00479 H00475 H00480 H00478 H00481 H00474 H00476 AVE SD RSD lOmin 3950 9600 2800 500 1260 1350 1260 1350 2759 2971 108

20min 11700 13600 7730 3140 8700 8490 8700 8490 8819 3043 35

3Qmin 11500 13500 8440 5400 7210 8180 7210 8180 8703 2586 30

B lOmin 1560 8480 3100 1230 6020 9130 1710 4461 3383 76

₂₀ min 52.60 14600 4910 4230 6090 8810 5710 7087 3618 51

30min 8230 14500 7790 4100 7660 10200 5100 8226 3429 42

C lOmin 4850 11100 5310 1780 4270 2880 2280 910 4173 3193 77

₂ Qmin 9570 13700 10700 6760 8510 7490 8240 8300 9159 2194 24

3Qmin 10900 11800 12700 5660 8160 9140 12100 9550 10001 2358 24

D lOmin 3840 2430 889 1280 4140 645 1870 1470 2071 1309 63

₂ 0min 6650 6350 3050 4110 4850 2800 4740 6120 4834 1469 30

30min 6640 5860 5360 4710 4760 4340 5670 7450 5599 1050 19

In Table 2, above, A, B, C, and D respectively represent the compositions of Examples 1, 2, 3 and 4 and HO0473 to HO0476 represent dog numbers.

(3) During the early time intervals post dose: (ten (10) to thirty (30) minutes post dosing), the compositions of Examples 1, 2 and 3, produced a higher truncated AUC of salicylic acid than was produced by the composition of Example 4.

Table 3, below, shows the truncated AUC values of salicylic acid for each dog in the study.

As shown in Table 3, at TlO after administration, the average level of truncated AUC of salicylic acid for the compositions of Examples 1 - 4, was 1322 ± 895 ng/ml*hr (Example 1), 1745 ± 645 ng/ml*hr (Example 2), 1517 ± 680 ng/ml*hr (Example 3) and 771 ± 398 ng/ml*hr (Example 4), respectively.

Figure 3 graphically illustrates, at each time point, the truncated AUCs of the compositions of Examples 1 - 4. At the final time point (180 minutes (T180) post dosing) the ratios of truncated AUC for salicylic acid (SA) for all compositions (Examples 1, 2, 3 and 4) were close to 100%. This indicates that the compositions of Examples 1, 2 and 3, in accordance with the present invention, were AUC bioequivalent to the composition of Example 4.

Surprisingly, although the compositions of the present invention were bioequivalent to a like composition that does not contain alkaline agent, at the early time points, the compositions of Examples 1, 2 and 3 were more than three (3) times higher in truncated AUC for salicylic acid than the composition of Example 4.

Table 3 The truncated AUC values of salicylic acid (ng/ml*hr) 10, 20 and 30 min post dosing.

AUC

SA

A HO0473 H00479 H00475 H00480 HO0478 H00481 H00474 HO0476 AVE SD RSD lOrain 1904 3181 1445 428 1027 512 827 1253 1322 895 68

₂₀ min 8025 11535 5170 2565 5232 3481 4071 5149 5654 2870 51

30min 17503 23418 11418 7572 12610 9984 9928 11490 12990 5095 39

B lOmin 1536 2321 1553 927 2196 2614 1069 1745 645 37

₂ 0min 6434 8254 6704 4326 8194 9762 5861 7076 1800 25

30min 14858 16669 15757 10157 17162 20302 14744 15664 3071 20

C lOmin 2280 2538 2054 1202 1378 1002 960 723 1517 680 45

20min 9216 9914 7881 5815 6594 5077 5255 4281 6754 2049 030

30min 19748 18805 16968 13865 15808 12897 13789 11948 15479 2834 018

D lOmin 1344 636 373 645 1303 347 508 1010 771 398 52

₂ Omin 5199 3286 1723 2904 4522 1712 2413 4563 3290 1344 41

30min 10945 7995 6322 6908 8985 4373 6017 10692 7780 2318 30

In Table 3, above, A, B, C, and D respectively represent the compositions of Examples 1, 2, 3 and 4 and HOO473 to HO0476 represent dog numbers.

(4) The compositions of Examples 1, 2 and 3 exhibited a higher truncated AUC of acetaminophen during the 10 minute, 20 minute and 30 minute post dose periods, as compared to the composition of Example 4 (a like composition but not containing alkaline agent).

Table 4, which follows, shows the truncated AUC values of acetaminophen in each dog in the study. As shown in Table 4, at T20 after administration, the average level of truncated AUC of acetaminophen present after administration of the compositions of Examples 1, 2 and 3 was 1174 ± 703 ng/ml*hr (Example 1), 1283 ± 833 ng/ml*hr (Example 2), 1422 ± 711 ng/ml*hr (Example 3) compared to 728 ± 314 ng/ml*hr after administration of the composition of Example 4..

Figure 4 graphically shows, for each of Examples 1 - 4, the truncated AUCs of acetaminophen at each time point. At the final point (T180) the ratios of truncated AUC for acetaminophen for the compositions of Examples 1, 2, 3 and 4 were close to 100%, indicating the compositions of Examples 1, 2 and 3 are all AUC bioequivalent to the composition of Example 4. However, at the early time points, the compositions of Examples 1, 2 and 3, in accordance with the present invention, exhibited a truncated AUC of acetaminophen more than three (3) times greater than that exhibited by the composition of Example 4.

Table 4

The truncated AUC values of acetaminophen (ng/ml*hr) at the 10, 20 and 30 minute time points.

AUC

APAP

A H00473 H00479 H00475 H00480 H00478 H00481 H00474 H00476 AVE SD RSD lOrnin 330 802 234 42 105 113 105 113 231 248 107

₂ Omin 1605 2693 1092 339 917 915 917 915 1174 703 60

30min 3577 4997 2466 1065 2269 2332 2269 2332 2663' 1159 44

B lOmin 130 708 42 103 503 762 143 342 308 90

₂ Omin 686 2589 695 548 1490 2224 748 1283 833 65

30min 1833 5063 1775 1256 2659 3840 1667 2585 1388 54

C lOmin 405 927 443 042 357 240 190 076 335 280 084

₂ 0min 1580 2948 1748 738 1399 1085 1047 827 1422 711 050

30min 3320 5116 3737 1794 2816 2499 2776 2344 3050 1023 034

D lOmin 321 203 74 42 346 54 156 123 165 117 71

20min 1176 919 395 481 1079 335 695 742 728 314 43

30min 2306 1957 1110 1231 1896 942 1580 1895 1615 479 30

In Table 4, above, A, B, C, and D respectively represent the compositions of Examples 1, 2, 3 and 4 and HO0473 to HO0476 represent dog numbers.

(5) The median (mean) T _max (acetaminophen) for Examples 1, 2, 3 and 4 were 0.50 (0.78), 0.75 (0.74), 0.50 (0.56), and 1.25 (1.29) hours, respectively.

The ANOVA model, based on the ranked T _max values, indicated that T _max (acetaminophen) for the compositions of Examples 1, 2 and 3 was statistically significantly lower than for the composition of Example 4.

The median (mean) T _max (salicylic acid) for the compositions of Examples .1, 2, 3 and 4 were 1.50 (1.68),1.25 (1.25),1.25 (1.21), and 1.50 (1.68) hours, respectively.

The ANOVA model based on the ranked T _max values (salicylic acid) indicated no statistically significant difference between the compositions of Example 1 and Example 2. However, the T _max (salicylic acid) for the compositions of Examples 2 and 3 was statistically significantly lower than the T _max (salicylic acid) for the composition of Example 4.

This data indicates that the compositions of Examples 1, 2 and 3, in accordance with the present invention, provided a faster onset of analgesic/antipyretic activity than the composition of Example 4.