Abstract:
The present invention relates to pharmaceutical combinations of opioid and non-opioid analgesics in an intimate admixture with an analgesic from a series of N-acylated 4-hydroxyphenylamine derivatives, linked via an alkylene bridge to the nitrogen atom of a 1,2-benzisothiazol-3(2H)-one 1,1-dioxide group and methods for their use to alleviate pain in mammals. The analgesic combinations exhibit enhanced analgesic potency and are free from antipyretic activity, do not suppress blood coagulation, and have little hepatotoxic effect.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS  
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         STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT  
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         REFERENCE TO A MICROFICHE APPENDIX  
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         COPYRIGHT NOTICE  
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         FIELD OF THE INVENTION  
         [0005]    The present invention relates to analgesic compositions for enhancing the efficacy and/or potency of certain opioid and non-opioid analgesics and which are free from antipyretic activity, do not suppress blood coagulation, and have little hepatotoxic effect. More particularly, the present invention relates to analgesic compositions that include analgesics referred to as the SCP series (SCP-1 through SCP-5) in combination with opioid and non-opioid analgesics.  
         BACKGROUND OF THE INVENTION  
         [0006]    Drug combinations such as acetaminophen and codeine (Tylenol III) or acetaminophen and oxycodone (Lortab) produce analgesia that is additive or synergistic. The rational for using such combinations is to reduce the dose of each analgesic, and thus reduce adverse effects and toxicity, while retaining or increasing analgesic efficacy. These acetaminophen combinations have greater efficacy for moderate to severe pain.  
           [0007]    For many types of pain (e.g. common headache, osteoarthritis) acetaminophen has equal potency and efficacy to acetylsalicylic acid (aspirin). However, the safety of acetaminophen has been questioned. There are approximately 100,000 cases of acetaminophen overdose annually, with approximately 30 deaths resulting. (Clissold, 1980; McGoldrick et al. 1997). Acetaminophen has a toxic metabolite, N-acetyl-benzoquinoneimine (NAPQI), which depletes hepatic and renal glutathione, a cytoprotective endogenous metabolite (Mason &amp; Fischer, 1986; Mitchell et al., 1983). Hepatic and renal toxicity with acetaminophen can occur at doses only 4- to 8-fold higher than the maximum recommended analgesic dose (Neuberger et al., 1980). Pharmaceutical combinations that contain acetaminophen and a centrally acting analgesic may be even more dangerous than acetaminophen alone. With repeated use these combinations require higher doses to produce the same analgesic effect because of an increase in tolerance. As the dose of the combination is increased to compensate for analgesic tolerance, the safety of the drug decreases as the higher doses of the acetaminophen component increase hepatic and renal toxicity.  
           [0008]    In U.S. Pat. No. 5,554,636 (Bazan et al.) and U.S. Pat. No. 5,621,110 (Bazan et al.), two of the inventors herein disclosed the series of N-acylated 4-hydroxyphenylamine derivatives linked via an alkylene bridge to the nitrogen atom of a 1,2-benzisothiazol-3(2H)-one 1,1-dioxide group along with the process for their preparation and methods of their use for alleviating pain. The disclosures of these patents are incorporated herein by reference. The SCP series is structurally depicted by the following general formula:  
                         
 
           [0009]    wherein n is a number from 1 to 5. These new non-narcotic analgesics surprisingly possess high analgesic activity free from antipyretic activity, do not suppress blood coagulation, and display little hepatotoxic effect. When the term “SCP series” is used herein, it is understood that any of the pharmaceutically suitable salts thereof are included by the term.  
           [0010]    The analgesic profiles of the SCP series are at least as good as that of acetaminophen. As expected, both types of drugs show little or no activity in the tail-flick and hotplate tests when compared with codeine. SCP-1 is more potent in the abdominal stretchs formalin, and Freund&#39;s adjuvant-induced inflammation assays of analgesia than acetaminophen. Acetaminophen is a potent antipyretic, whereas SCP-1 at doses up to 904 μmoles/kg (300 mg/kg) has no antipyretic effect. SCP-1 is lower in toxicity, and, of even greater importance, lower in hepatotoxicity (Paul et al., 1998). All of these properties make SCP-1 and related derivatives potentially very useful pharmacologic agents.  
         OBJECTS AND SUMMARY OF THE INVENTION  
         [0011]    It is an object of the invention to provide pharmaceutical combinations comprising an analgesic from the SCP series along with an opioid or a non-opioid analgesic that has an analgesic profile at least as good as an acetaminophen/opioid analgesic or acetaminophen/non-opioid analgesic combinations.  
           [0012]    It is another object of the invention to provide pharmaceutical combinations comprising an analgesic from the SCP series along with an opioid or non-opioid analgesic that has no antipyretic effect at doses up to 904 μmoles/kg (300 mg/kg).  
           [0013]    It is another object of the invention to provide pharmaceutical combinations comprising an analgesic from the SCP series along with an opioid or non-opioid analgesic that has lower hepatotoxicity than acetaminophen/opioid analgesic or acetaminophen/non-opioid analgesic combinations.  
           [0014]    It is yet another object of the invention to provide pharmaceutical combinations comprising an analgesic from the SCP series along with an opioid or non-opioid analgesic that supplants acetaminophen/opioid analgesic or acetaminophen/non-opioid analgesic combinations in cases where fever control would be contraindicated.  
           [0015]    It is still another object of the invention to provide pharmaceutical combinations comprising an analgesic from the SCP series along with an opioid or non-opioid analgesic that does not suppress blood coagulation, and therefore can be used as a pre-emptive analgesic for procedures expected to produce mild post-surgical pain. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0016]    [0016]FIG. 1 shows the analgesic effect of SCP-1 compared to codeine and acetaminophen.  
         [0017]    [0017]FIG. 2 shows an isobologram for acetaminophen and codeine compared to an isobologram for SCP-1 and codeine.  
         [0018]    [0018]FIG. 3 shows the hepatotoxicity of SCP-1 alone and in combination with codeine compared to acetaminophen alone and in combination with codeine in C57/b16 mice. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0019]    The most commonly employed method of managing pain involves the systemic administration of analgesics. Analgesics by definition include drugs that through their action on the nervous system reduce or abolish the perception of pain without producing unconsciousness. Traditionally, analgesics fall into two broad categories: (1) simple, non-narcotic analgesics, such as aspirin, which appear to work by inhibition of prostaglandin synthetase, and (2) narcotic analgesics, which appear to work through interaction with the endorphin/enkephalin receptor system of the central nervous system. The term “narcotic” has historically been associated with the strong opioid analgesics, but the term is not very useful in a pharmacological context. More appropriately, the category referred to as narcotic analgesics, can be further divided into two groups, the opioids and non-opioids. The term “opioids” refers to drugs with morphine like activity (agonists and antagonists), acting on mu, delta and kappa receptors. The term “non-opioids” refers to drugs that act via a different mechanism.  
         [0020]    The drugs that comprise the group known as the opioid analgesics include among others the phenanthrene alkaloids of opium, comprising morphine, codeine, and thebaine. While thebaine produces no analgesia, it is an important intermediate in the production of semisynthetic opioids. Other agents with structures and function related to morphine include: (1) the morphine analogs, such as hydromorphone, oxymorphone, hydrocodone, and oxycodone; (2) Diels-Alder adducts, such as etorphine and buprenorphine; (3) the morphinan derivatives, such as dextromethorphan and butorphanol; (4) the benzomorphan derivatives, such as phenazocine, pentazocine and cyclazocine; (5) the piperidine derivatives, such as meperidine and anileridine; and (6) open chain analgesics (methadone type compounds), such as methadone and propoxyphene. The drugs that comprise the group known as the non-opioid analgesics include: (1) N-methyl-D-aspartate (NMDA) receptor antagonists, such as dextromethorphan and ketamine and other antagonists that suppress central sensitization by competing for any of the binding site subcategories associated with the NMDA receptor, e.g., the glycine binding site, the phenylcyclidine (PCP) binding site, etc., as well as the NMDA channel; (2) alpha 2  adrenoreceptor agonists, such as clonidine, metomidine, detomidine, dexmetomidine, dexmedetomidine and xylazine, that reduce the release of norepinephrine; (3) other agents, such as tramadol, often mistakenly referred to as an opioid, that produce analgesia by their inhibitory actions on monoamine re-uptake rather than by agonist effect; (4) non-steroidal anti-inflammatory drugs such as aspirin, ibuprofen and other drugs that inhibit cyclooxygenase enzymes and (5) mixed agonist-antagonist analgesics such as buprenorphine, dezocine, nalbuphine.  
         [0021]    Opioid and non-opioid analgesics may cause a variety of side effects including sedation, constipation, hypotension, nausea, vomiting, elevation of cerebrospinal fluid pressure, respiratory depression, physical dependence and tolerance. Therefore, there is a serious need to develop combinations of drugs that supplement the activity of the opioid and non-opioid analgesics, which allows the use of smaller doses of the opioid and non-opioid analgesics. One way of achieving this result is to enhance the analgesic activity of a known opioid or non-opioid analgesic by the addition of a second non-narcotic analgesic. However, it is difficult to predict when a synergistic effect will be obtained from two pharmaceutical compositions that take effect through different mechanisms.  
         [0022]    The SCP series are non-narcotic analgesics that are free from antipyretic activity and have little hepatotoxic effect. The compounds in this series do not produce the metabolite that is responsible for acetaminophen toxicity and they do not reduce fever. As a result, they are more useful than acetaminophen and other non-narcotic analgesics in the treatment of chronic pain and in situations in which controlling fever is contraindicated, such as after surgery, where fever control can mask infection. Moreover, unlike conventional non-narcotic analgesics, such as aspirin or ibuprofen, the SCP series does not suppress blood coagulation. Children, the elderly and liver-compromised patients would also benefit from the administration of SCP for the treatment of pain. Pharmaceutical combinations utilizing the SCP series with opioid and non-opioid analgesics has been found to provide enhanced analgesia without antipyretic activity, without suppressing blood coagulation, and without the toxicity associated with conventional non-narcotic analgesics.  
         [0023]    The pharmaceutical combinations of the present invention comprise an opioid or a non-opiod analgesic in an intimate admixture with an analgesic from the SCP series along with a pharmaceutically acceptable carrier prepared according to conventional pharmaceutical techniques. Pharmaceutically acceptable carriers include solid or liquid fillers, diluents, and encapsulating substances. The amount of the carrier employed in conjunction with the combination is sufficient to provide a practical quantity of material per unit dose of analgesic.  
         [0024]    Pharmaceutically acceptable carriers for oral administration include, sugars, starches, cellulose and its derivatives, malt, gelatin, talc, calcium sulfate, vegetable oils, synthetic oils, polyols, alginic acid, phosphate buffer solutions, emulsifiers, isotonic saline, and pyrogen-free water. Pharmaceutically acceptable carriers for parenteral administration include isotonic saline, propylene glycol, ethyl oleate, pyrrolidone, aqueous ethanol, sesame oil, corn oil, and combinations thereof.  
         [0025]    Various oral dosages forms can be employed, including solid forms such as tablets, capsules, granules and bulk powders. Tablets can be compressed, tablet triturates, enteric-coated, sugarcoated, film-coated or multiple compressed, containing suitable binders, lubricants, diluents, disintegrating agents, coloring agents, flavoring agents, flow-inducing agents, and melting agents. Liquid oral dosage forms include aqueous solutions, emulsions, suspensions, and reconstituted solutions and/or suspensions.  
         [0026]    Pharmaceutically effective combinations can contain between 0.1 and 1000 mg of an analgesic from the SCP series. The preferred pharmaceutically effective combinations contain between 400 and 1000 mg of an analgesic from the SCP series. The pharmaceutically effective amounts of the opioid and non-opioid analgesics in combination with analgesics in the SCP series are similar to the corresponding combinations of opioid and non-opioid analgesics with acetaminophen. The following examples are illustrative of pharmaceutically effective combinations of the present invention:  
                                                                                                                                                                                                                                                                                                                                                                                                                                             Example 1: Codiene            Dosage of SCP (mg):    100-1000       Dosage of Codiene (mg):    0.1-100        Preferred Ratios for Oral Dosage (mg codeine:mg SCP):    15:450            30:450            60:450       Preferred Weight Ratios for Injectable Delivery (codeine:SCP):    1:10           1:5            Example 2: Morphine            Dosage of SCP (mg):    100-1000       Dosage of Morphine (mg):    0.1-100        Preferred Ratios for Oral Dosage (mg morphine:mg SCP):    15:450            30:450            60:450       Preferred Weight Ratios for Injectable Delivery (morphine:SCP):    1:60            1:30            Example 3: Hydrocodone            Dosage of SCP (mg):    100-1000       Dosage of Hydrocodone (mg):    0.1-100        Preferred Ratios for Oral Dosage (mg hydrocodone:mg SCP):    2.5:450             5:450            7.5:450             10:450       Preferred WeightRatios for Injectable Delivery (hydrocodone:SCP):    1:200            1:100            Example 4: Dihydrocodone            Dosage of SCP (mg):    100-1000       Dosage of Dihydrocodone (mg):    0.1-100        Preferred Ratios for Oral Dosage (mg dihydrocodone:mg SCP):    10:450            36:450       Preferred Weight Ratios for Injectable Delivery (dihydrocodone:SCP):    1:100            1:50            Example 5: Oxycodone            Dosage of SCP (mg):    100-1000       Dosage of Oxycodone (mg):    0.1-100        Preferred Ratios for Oral Dosage (mg oxycodone:mg SCP):    5:450       Preferred Weight Ratios for Injectable Delivery (oxycodone:SCP):    1:200            Example 6: Controlled Release Oxycodone            Dosage of SCP (mg):    100-1000       Dosage of Oxycodone (mg):    0.1-100        Preferred Weight Ratios for Oral Dosage (mg oxycodone:mg SCP):    10:900            20:900            40:900            60:900            Example 7: Meperidine            Dosage of SCP (mg):    100-1000       Dosage of Meperidine (mg):    0.1-500        Preferred Ratios for Oral Dosage (mg merperidine:mg SCP):    25:450            50:450       Preferred Weight Ratios for Injectable Delivery (merperidine:SCP):    1:20            1:10            Example 8: Propoxyphene            Dosage of SCP (mg):    100-1000       Dosage of Propoxyphene (mg):    0.1-500        Preferred Ratios for Oral Dosage (mg propoxyphene:mg SCP):    65:450           100:450       Preferred Weight Ratios for Injectable Delivery (propoxyphene:SCP):    1:10            Example 9: Levorphanol            Dosage of SCP (mg):    100-1000       Dosage of Levorphanol (mg):    0.1-100        Preferred Ratios for Oral Dosage (mg levorphanol:mg SCP):    4:450       Preferred Weight Ratios for Injectable Delivery (levorphanol:SCP):    1:100            Example 10: Oxymorphone            Dosage of SCP (mg):    100-1000       Dosage of Oxymorphone (mg):    0.1-200        Preferred Ratios for Oral Dosage (mg oxymorphone:mg SCP):    5:450       Preferred Weight Ratios for Injectable Delivery (oxymorphone:SCP):    1:100            Example 11: Hydromorphone            Dosage of SCP (mg):    100-1000       Dosage of Hydromorphone (mg):    0.1-100        Preferred Ratios for Oral Dosage (mg hydromorphone:mg SCP):    1:450            3:450            5:450            8:450       Preferred Weight Ratios for Injectable Delivery (hydromorphone:SCP):    1:450            1:150            1:100            1:50            Example 12: Fentanyl            Dosage of SCP (mg):    100-1000       Dosage of Fentanyl (mcg):    0.1-500        Preferred Ratios for Oral Dosage (mcg fentanyl:mg SCP):    10:450            50:450       Preferred Weight Ratios for Injectable Delivery (fentanyl:SCP):     1:1000            Example 13: Alfentanyl            Dosage of SCP (mg):    100-1000       Dosage of Alfentanyl (mcg):   0.01-50         Preferred Ratios for Oral Dosage (mcg alfentanyl:mg SCP):    1:450            5:450       Preferred Weight Ratios for Injectable Delivery (alfentanyl:SCP):     1:10000            Example 14: Sufentanyl            Dosage of SCP (mg):    100-1000       Dosage of Sufentanyl (mcg):    0.1-500        Preferred Ratios for Oral Dosage (mcg sufentanyl:mg SCP):    10:450            50:450       Preferred Weight Ratios for Injectable Delivery (sufentanyl:SCP):     1:10000            Example 15: Remifentanyl            Dosage of SCP (mg):    100-1000       Dosage of Remifentanyl (mcg):    0.1-500        Preferred Ratios for Oral Dosage (mcg remifentanyl:mg SCP):    1:450            5:450       Preferred Weight Ratios for Injectable Delivery (remifentanyl:SCP):      1:100000            Example 16: Levomethadyl            Dosage of SCP (mg):    100-1000       Dosage of Levomethadyl (mg):    0.1-200        Preferred Ratios for Oral Dosage (mg levomethadyl:mg SCP):    10:450           140:450       Preferred Weight Ratios for Injectable Delivery (levomethadyl:SCP):    1:10           1:4            Example 17: Methadone            Dosage of SCP (mg):    100-1000       Dosage of Methadone (mg):    0.1-200        Preferred Ratios for Oral Dosage (mg methadone:mg SCP):    5:450            10:450            40:450       Preferred Weight Ratios for Injectable Delivery (methadone:SCP):    1:100            1:50            1:10            Example 18: Buprenorphine            Dosage of SCP (mg):    100-1000       Dosage of Buprenorphine (mg):   0.01-100        Preferred Ratios for Oral Dosage (mg buprenorphine:mg SCP):    1:450       Preferred Weight Ratios for Injectable Delivery (buprenorphine:SCP):    1:100            Example 19: Butorphanol            Dosage of SCP (mg):    100-1000       Dosage of Butorphanol (mg):    0.1-200        Preferred Ratios for Oral Dosage (mg butorphanol:mg SCP):    20:450       Preferred Weight Ratios for Injectable Delivery (butorphanol:SCP):    1:20            Example 20: Dezocine            Dosage of SCP (mg):    100-1000       Dosage of Dezocine (mg):    0.1-200        Preferred Ratios for Oral Dosage (mg dezocine:mg SCP):    15:450            30:450            60:450       Preferred Weight Ratios for Injectable Delivery (dezocine:SCP):    1:60            1:30            Example 21: Nalbuphine            Dosage of SCP (mg):    100-1000       Dosage of Nalbuphine (mg):    0.1-200        Preferred Ratios for Oral Dosage (mg nalbuphine:mg SCP):    50:450       Preferred Weight Ratios for Injectable Delivery (nalbuphine:SCP):    1:60            Example 22: Pentazocine            Dosage of SCP (mg):    100-1000       Dosage of Pentazocine (mg):    0.1-500        Preferred Ratios for Oral Dosage (mg pentazocine:mg SCP):    25:450            50:450       Preferred Weight Ratios for Injectable Delivery (pentazocine:SCP):    1:20            1:10            Example 23: Tramadol            Dosage of SCP (mg):    100-1000       Dosage of Tramadol (mg):    0.1-500        Preferred Ratios for Oral Dosage (mg tramadol:mg SCP):    50:450       Preferred Weight Ratios for Injectable Delivery (tramadol:SCP):    1:10            Example 24: Clonidine            Dosage of SCP (mg):    100-1000       Dosage of Clonidine (mg):   0.01-100        Preferred Ratios for Oral Dosage (mg clonidine:mg SCP):    1:450       Preferred Weight Ratios for Injectable Delivery (clonidine:SCP):    1:450            Example 25: Aspirin            Dosage of SCP (mg):    100-1000       Dosage of Aspirin (mg):    0.1-1000        Preferred Ratios for Oral Dosage (mg aspirin:mg SCP):   250:450       Preferred Weight Ratios for Injectable Delivery (aspirin:SCP):   1:2                  
 
         [0027]    As shown in FIG. 1, the analgesic potency of SCP-1 is greater than that of acetaminophen in the abdominal stretch assay. In this assay of pain, the number of stretches exhibited by a mouse after an intraperitoneal (i.p.) injection of dilute acetic acid (Koster et al., 1959) are counted. The analgesic compounds (acetaminophen, SCP-1, or codeine) were administered orally and fifty-five minutes later, the mice (groups of 8 or more) received a second i.p. injection of 10 ml/kg of 0.4% acetic acid. The number of abdominal stretches was counted beginning 5 minutes after the second acetic acid injection for a period of 10 minutes. For each of the compounds tested, the percentage of the number of stretches obtained in control animals (29±2.1) was calculated. All three compounds produced a dose-dependent decrease in the number of abdominal stretches, however, the potency of SCP-1 was significantly greater than acetaminophen.  
         [0028]    As shown in FIG. 2, an isobolographic analysis was performed to demonstrate the synergistic effect of an SCP-1/narcotic analgesic pharmaceutical combination. The isobologram is a quantitative method for measuring interactions between drugs where dose-effect relationships are depicted in a multi-dimensional array with lines connecting dose pairs that are equieffective in relationship to a common pharmacological endpoint. Most importantly, the isobolographic analysis permits a full range of doses and dose combinations to be examined where the proportion of the first drug to the second actually varies from 0 to infinity, and to determine, by virtue of the graphical display, whether any one or more of the paired drug combinations displays unique pharmacological properties in comparison to the entire body of generated data.  
         [0029]    Groups of mice (n=10) were administered a dose of acetaminophen, SCP-1, or codeine to define a dose-response curve for each drug in the abdominal stretch assay. The ED 50  for each drug was calculated using nonlinear regression analysis. Subsequently, a combination of acetaminophen and codeine or a combination of SCP-1 and codeine was tested using the same assay. The ratios of acetaminophen to codeine or SCP-1 to codeine were equivalent to the ratios of the ED 50 s of each drug alone. Dose-response curves for the drug combination ratios were produced and ED 50 s calculated. The ED 50 s were graphed according to the method of Tallarida et al., (1997). Briefly, the dose of one drug is depicted on the X-axis with a linear scale and a range of 0 to its ED 50 . The dose of the other drug is likewise depicted on the Y-axis. A line is drawn diagonally from ED 50  to ED 50 . This line is known as the line of additivity, as any combination of X and Y doses that fall upon this line would be predicted to produce 50% analgesia. The experimental ED 50  is plotted according to the dose of each individual drug and the standard error oriented on a line from the origin through the data point. Thus, when the ED 50  of the drug combination is plotted, any point (+standard error) closer to the origin than the line of additivity would be considered to be synergistic (producing more analgesia than expected based on simple additivity) and any point farther from the origin than the line of additivity would be considered to be antagonistic (producing less analgesia than expected based on simple additivity). The combination of acetaminophen and codeine produced analgesia synergistically (see FIG. 2A). The combination of SCP-1 and codeine also produced analgesia synergistically (see FIG. 2B).  
         [0030]    A study was also devised to assess the toxicity of SCP-1 in combination with codeine in comparison to the toxicity of acetaminophen in combination with codeine, the results of which are depicted in FIG. 3. The study was performed on C57/b16 mice weighing 22-25 g. The mice were administered doses of acetaminophen, SCP-1, codeine, a combination of acetaminophen and codeine, or a combination of SCP-1 and codeine in a corn oil vehicle using an esophageal cannula. The administered doses of acetaminophen and SCP-1 were equivalent to the acetaminophen LD50 in mice (3.7 mmole/kg) and the administered dose of codeine was 50 mg/kg. After 24 hours, plasma activity levels of glutamic/pyruvic transaminase (GPT) and glutamic/oxalacetic transaminase (GOT) were obtained to assess hepatotoxic levels of drugs. As shown in FIG. 3, acetaminophen produced a large increase in GPT activity in serum, but neither SCP-1 nor codeine, nor the combination of both, produced any significant increase in activities.  
         [0031]    It is apparent from the instant specification that various modifications and changes may be made by those skilled in the art. It is therefore intended that the following claims be interpreted as covering all modifications and changes that fall within the true spirit and scope of the invention.