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(12) INTERNATIONAL APPLICATION PUBLISHED UNDER THE PATENT COOPERATION TREATY (PCT) (19) World Intellectual Property Organization International Bureau (10) International Publication Number (43) International Publication Date Τ t t It t C C 20 October 2011 (20.10.2011) 2U11/13U455 Al (51) International Patent Classification: DZ, EC, EE, EG, ES, FI, GB, GD, GE, GH, GM, GT, A01N 43/40 (2006.01) A61K 31/44 (2006.01) HN, HR, HU, ID, IL, IN, IS, JP, KE, KG, KM, KN, KP, KR, KZ, LA, LC, LK, LR, LS, LT, LU, LY, MA, MD, (21) International Application Number: ME, MG, MK, MN, MW, MX, MY, MZ, NA, NG, NI, PCT/US201 1/032381 NO, NZ, OM, PE, PG, PH, PL, PT, RO, RS, RU, SC, SD, (22) International Filing Date: SE, SG, SK, SL, SM, ST, SV, SY, TH, TJ, TM, TN, TR, 13 April 201 1 (13.04.201 1) TT, TZ, UA, UG, US, UZ, VC, VN, ZA, ZM, ZW. (25) Filing Language: English (84) Designated States (unless otherwise indicated, for every kind of regional protection available): ARIPO (BW, GH, (26) Publication Language: English GM, KE, LR, LS, MW, MZ, NA, SD, SL, SZ, TZ, UG, (30) Priority Data: ZM, ZW), Eurasian (AM, AZ, BY, KG, KZ, MD, RU, TJ, 61/323,780 13 April 2010 (13.04.2010) US TM), European (AL, AT, BE, BG, CH, CY, CZ, DE, DK, EE, ES, FI, FR, GB, GR, HR, HU, IE, IS, ΓΓ, LT, LU, (72) Inventor; and LV, MC, MK, MT, NL, NO, PL, PT, RO, RS, SE, SI, SK, (71) Applicant : BABUL, Najib [US/US]; 146 Medinah SM, TR), OAPI (BF, BJ, CF, CG, CI, CM, GA, GN, GQ, Drive, Blue Bell, PA 19422-3212 (US). GW, ML, MR, NE, SN, TD, TG). (74) Common Representative: BABUL, Najib; 146 Medinah Published: Drive, Blue Bell, PA 19422-3212 (US). — with international search report (Art. 21(3)) (81) Designated States (unless otherwise indicated, for every — before the expiration of the time limit for amending the AE, AG, AL, AM, kind of national protection available): claims and to be republished in the event of receipt of AO, AT, AU, AZ, BA, BB, BG, BH, BR, BW, BY, BZ, amendments (Rule 48.2(h)) CA, CH, CL, CN, CO, CR, CU, CZ, DE, DK, DM, DO, o o (54) Title: DERMAL PHARMACEUTICAL COMPOSITIONS OF l-METHYL-2',6'-PIPECOLOXYLIDIDE AND METHOD OF USE (57) Abstract: The present invention is directed to therapeutic pharmaceutical compositions of l-Methyl-2', 6'-pipecoloxylidide or it pharmaceutically acceptable salts for application to the skin and the use thereof. DERMAL PHARMACEUTICAL COMPOSITIONS OF l-METHYL-2 .6'- PIPECOLOXYLIDIDE AND METHOD OF USE [0001] This application is entitled to priority to the applicant's U.S. provisional patent application No. 6 1/323,780, filed April 13, 2010 which is herein incorporated in its entirety for all purposes. FIELD OF THE INVENTION [0002] The present invention is directed to therapeutic pharmaceutical compositions of 1- methyl-2',6'-pipecoloxylidide or it pharmaceutically acceptable salts for application to the skin and the use thereof. BACKGROUND OF THE INVENTION [0003] The present invention relates to the application of l -methyl-2',6'-pipecoloxylidide (mepivacaine) to the skin for the treatment of mepivacaine responsive medical conditions such as pain and neuropathy. Mepivacaine [0004] Mepivacaine was synthesized in the mid 1950's in Sweden and introduced into clinical medicine in 1957 as an injectable local anesthetic. Presently injectable mepivacaine is indicated "for the production of local or regional analgesia and anesthesia by local infiltration, peripheral nerve block techniques, and central neural techniques including epidural and caudal blocks." To the applicant's knowledge, there are no working prototypes or therapeutic trials of mepivacaine in the prior art for application to the skin to treat pain. [0005] In order to provide analgesia following application to the skin, a local anesthetic must be able to reach the epidermis and dermis where the cutaneous nerve endings are located, and once there it must be capable of blocking the generation and/or propagation of aberrant or ectopic impulses in sensory nerve fibers. The former property depends on the pharmacokinetic behavior of the local anesthetic, i.e., how efficiently it can penetrate the stratum corneum (the outermost layer of the skin), and how long it dwells in the deeper skin layers before diffusing into underlying tissue. The latter property depends on the pharmacologic activity of the local anesthetic, i.e., its ability to bind to and inhibit specific ion channels essential for the generation and/or propagation of the aberrant or ectopic impulses in sensory nerve fibers. [0006] Although lidocaine has demonstrated some efficacy when applied to the skin of patients with certain pain states, these results are not generalizable to other local anesthetics. For example, an important predictor of skin penetration and penetration into the receptor site for local anesthetics is its octanol:water partition coefficient. In one report, the octanol:water partition coefficient of lidocaine was 3.6 fold greater than for mepivacaine (Ferrante FM, Pharmacology of local anesthetics, p. 330- 1362, In: Longnecker DE, Tinker JH, Morgan, Jr., GE (eds), Principles and practice of anesthesiology, 1998 (2nd ed), Mosby-Year Book, Inc. St. Louis, Missouri). In another study, the octanol:water partition coefficient of lidocaine was 2.6 fold greater than for mepivacaine. Similarly, the ratio of relative concentrations of protonated and neutral drug, respectively, between octanol and water was 2.8 fold greater for Lidocaine, compared with mepivacaine (Strichartz GR, Sanchez V, Arthur GR, Chafetz R, Martin D. Fundamental properties of local anesthetics. II. Measured octanokbuffer partition coefficients and pKa values of clinically used drugs. Anesth Analg 1990;7 1:158-70.). All of the foregoing observations support the superior skin and subsequent nerve tissue penetration of lidocaine and the purported lack of efficacy for mepivacaine when applied to the skin. Goodman & Gilman's The Pharmacological Basis of Therapeutics, a textbook of pharmacology used by physicians from all therapeutic and surgical specialties, clinical pharmacologists, clinical research professionals and pharmacists states that "Mepivacaine is not effective as a topical anesthetic". [0007] Neuropathic pain [0008] Pain is most often classified by time course, etiology or mechanism as acute pain, inflammatory pain, visceral pain, breakthrough pain, nociceptive pain, neuropathic pain, chronic pain, or cancer-related pain. [0009] The International Association for the Study of Pain (IASP) defines neuropathic pain as "pain initiated or caused by a primary lesion or dysfunction of the nervous system". Neuropathic pain may be classified as peripheral neuropathic pain and central neuropathic pain (central pain). Many terms may be used by patients with neuropathies to describe their painful neuropathic sensations. Clinical trials of putative analgesics will frequently assess: (i) steady pain (patient descriptors often include "burning", "aching", "stinging", "throbbing", "itching", "numbing", "pins & needles", "pulling"; (ii) brief pain (patient descriptors often include "sharp", "jabbing", "shooting", "electric"; and (iii) evoked pain (assessed by the clinician or self-reported using "mechanical" and "thermal stimulus). (Watson and Babul, Neurology, 1998). [0010] Pharmacological investigations have been conducted in a wide variety of painful neuropathies, particularly peripheral neuropathies. Among the peripheral neuropathies most widely investigated for pharmacologic response are painful diabetic neuropathy, postherpetic neuralgia, trigeminal neuralgia and painful HIV-associated distal symmetrical neuropathy. [001 1] It is estimated that approximately 20 million individuals in the United States have diabetes and about one-fifth of them suffer from painful diabetic neuropathy, which is a distal, symmetrical, axonal-sensory neuropathy usually involving the feet and legs initially and later the hands. A limited number of treatment options are available for the treatment of painful diabetic neuropathy and only two drugs (pregabalin and duloxetine) have been approved by the Food and Drug Administration (FDA) for the treatment of this condition. Even for effective and /or approved drugs, pain relief is often suboptimal and few patients obtain a complete response. Importantly, these pharmacologic agents can have troublesome side effects, an important issue given the co-morbid pathology in many patients with diabetes. [0012] To the applicant's knowledge, there are no data from placebo controlled randomized clinical trials (which are considered the gold standard in evidence based medicine) demonstrating the efficacy of any local anesthetic application to the skin for the treatment of painful diabetic neuropathy. [0013] HIV infection and HIV medications are both associated with the development of neuropathy which usually manifests as distal, symmetrical, predominantly sensory, polyneuropathy [Bailey et al, 1988; Corblath and MacArthur, 1988; Fuller et al, 1993]. Causative factors include nerve infiltration by HIV and the toxicity of antiretrovirals such as didanosine (ddl) or zalcitabine (ddC) [Fuller et al, 199 1; Grafe and Wiley, 1989; Griffin et al, 1994; Paice et al, 2000; Penfold and Clark, 1992; Rizzuto et al, 1995; Simpson and Olney, 1992]. Progressive and painful HIV-associated neuropathy significantly impairs patients' quality of life, and it impairs function, by rendering walking difficult. Painful HIV-associated neuropathy is also a toxicity of antiretroviral therapy and as such it limits patients' ability to remain on antiviral regimens containing