Patent Abstract:
a - and / or b - ring substituted camptothecin derivatives , which are poorly water soluble , are highly lipophilic camptothecin derivatives and are very active against a variety of human cancers . because of their very poor water solubility , hlcd have not been used to treat human patients with cancer due to the inability to administer sufficient quantities of the hlcd dissolved in a pharmaceutical formulation . this invention overcomes these limitations by teaching novel pharmaceutically acceptable hlcd formulations for the direct administration of hlcd to human patients with cancer . the claimed invention also describes the methods to create solutions of hlcd and antitumor compositions of hlcd to allow the administration of hlcd in sufficient amounts to treat human patients with various types of cancer . this invention is also directed to injectable sterile solutions , antitumor compositions , solutions and suspensions comprising n - methyl - 2 - pyrrolidinone and a highly lipophilic camptothecin derivative .

Detailed Description:
in its preferred embodiments , this invention involves preparation and use of novel hlcd solutions or suspensions as described below . for the purposes of this invention , the terms &# 34 ; lower alkyl &# 34 ; and &# 34 ; lower alcohol &# 34 ; are given their usual and customary meanings . as described in the prior art , &# 34 ; lower alkyl &# 34 ; means a straight or branched chain hydrocarbon of from 1 to 6 carbon atoms . some groups included within the definition are methyl , ethyl , propyl , isopropyl , butyl , isobutyl , sec - butyl , tert - butyl , pentyl and hexyl . &# 34 ; lower alcohol &# 34 ; means an alcohol having a straight or branched chain hydrocarbon group of from 1 to 6 carbon atoms . included within this definition are methanol , ethanol , propanol , isopropanol , butanol , and others . the following examples illustrate selected modes for carrying out the claimed invention and are not to be construed as limiting the specification and claims in any way . these examples are provided so as to enable those in ordinary skill in the art to make the compositions of this invention . these examples are not intended to limit the scope of what the inventors regard as the invention . efforts have been made to ensure accuracy with respect to numbers used to characterize the measured conditions ; however , some experimental errors and deviations may be present . maintaining an acidic ph ( 3 to 5 ) in the hlcd solution or suspension is particularly important to reduce the slow conversion of hlcd lactone to the e - ring - hydrolyzed carboxylate , which occurs at physiological ph . at equilibrium under physiologic ph , the ratio of the open - ring ( carboxylate ) form to lactone species increases . hydrolysis of the hlcd lactone ring will be substantially reduced if the drug is kept in an acidic environment . some of the unpredictable toxicity seen in earlier clinical trials using scpt may have been due to the in vivo formation of greater amounts of the lactone form of camptothecin , which is 10 - fold more toxic than scpt in mice . the lactone form of hlcd , as in camptothecin , is less water soluble than the carboxylate e - ring form . when early clinical trials were first conducted with camptothecin using sodium hydroxide , the significance of maintaining the closed lactone ring for uniform efficacy and safety in treating patients with cancer was poorly understood . the early reported unpredictable clinical toxicities associated with camptothecin administration may have been exacerbated by the sodium hydroxide formulation which promotes the formation of the carboxylate form , and by the relative lack of understanding of the significance of the lactone form of camptothecin as it relates to antitumor activity . for injection or infusion into aqueous body fluids , a formulation contains from about 1 . 0 to about 40 . 0 parts by weight of hlcd in 1 , 000 to 10 , 000 parts by weight of nmp in a vehicle comprising between about 1 , 000 to about 5 , 000 part by weight of an acceptable alcohol , about 1 , 000 to about 10 , 000 parts by weight of polyethylene glycol , and about 1 , 000 to about 10 , 000 parts of a non - ionic surfactant . suitable alcohols include dehydrated ethyl alcohol or benzyl alcohol , or combination of ethyl alcohol and benzyl alcohol . suitable polyethylene glycols , include polyethylene glycol 300 , polyethylene glycol 400 , and polypropylene glycol . suitable non - ionic surfactants include polysorbate - 80 ( tween - 80 ). in a preferred embodiment , the formulation of hlcd is supplied as an intravenous injectable in a vial comprising a solution of drug in a vehicle comprising ethyl alcohol and / or benzyl alcohol , citric acid , polyethylene glycol 400 , and polysorbate ( tween 80 ). a second formulation contains from about 1 . 0 to about 40 . 0 parts by weight of hlcd in 1 , 000 to 10 , 000 part of nmp further comprising between about 1 , 000 to 5 , 000 parts of an alcohol , about 100 to 5 , 000 parts by weight of an pharmaceutically acceptable acid and about 1 , 000 to 10 , 000 parts of polyethylene glycol 400 . suitable alcohols include ethyl alcohol , and benzyl alcohol . suitable acids for this formulation include citric acid , hydrochloric acid or phosphoric acid . in a preferred embodiment 1 to about 20 parts of hlcd by weight is formulated in 1 , 000 to 10 , 000 parts of nmp , 1 , 000 to 10 , 000 parts of peg - 400 , 1 , 000 to 5 , 000 parts by weight ethyl alcohol , and 1 , 000 to 5 , 000 parts of citric acid by weight . an oral formulation of hlcd in soft gelatin capsules ( comprised of gelatin / glycerin / sorbitol / purifiers ) containing from about 1 . 0 part to about 40 . 0 parts by weight of hlcd dissolved in 1 , 000 to 10 , 000 parts of nmp , citric acid 1 , 000 to about 5 , 000 parts by weight , glycerin 0 . 5 to 2 . 5 parts by weight , and polyethylene glycol ( peg - 300 or peg - 400 ) 1 , 000 to 10 , 000 parts by weight , ethyl alcohol 1 , 000 to 5 , 000 parts by weight , and taurocholic acid 1 to 10 parts by weight . the soft gelatin capsules may also be composed of any of a number of compounds used for this purpose including for example , a mixture of gelatin , glycerin , sorbitol , and parabens . a formulation containing from about 1 . 0 to about 40 . 0 parts by weight of 7 - ethyl camptothecin in 1 , 000 to 10 , 000 part of nmp further comprising between about 1 , 000 to 5 , 000 parts of an alcohol , about 100 to 5 , 000 parts by weight of an pharmaceutically acceptable acid and about 1 , 000 to 10 , 000 parts of polyethylene glycol 400 . suitable alcohols include ethyl alcohol , and benzyl alcohol . suitable acids for this formulation include citric acid , hydrochloric acid or phosphoric acid . in a preferred embodiment 1 to about 20 parts of 7 - ethyl camptothecin by weight is formulated in 1 , 000 to 10 , 000 parts of nmp , 1 , 000 to 10 , 000 parts of peg - 400 , 1 , 000 to 5 , 000 parts by weight ethyl alcohol , and 1 , 000 to 5 , 000 parts of citric acid by weight . a formulation containing from about 1 . 0 to about 40 . 0 parts by weight of 7 - ethyl - 10 - hydroxy camptothecin in 1 , 000 to 10 , 000 part of nmp further comprising between about 1 , 000 to 5 , 000 parts of an alcohol , about 100 to 5 , 000 parts by weight of an pharmaceutically acceptable acid and about 1 , 000 to 10 , 000 parts of polyethylene glycol 400 . suitable alcohols include ethyl alcohol , and benzyl alcohol . suitable acids for this formulation include citric acid , hydrochloric acid or phosphoric acid . in a preferred embodiment 1 to about 20 parts of 7 - ethyl - 10 - hydroxy camptothecin by weight is formulated in 1 , 000 to 10 , 000 parts of nmp , 1 , 000 to 10 , 000 parts of peg - 400 , 1 , 000 to 5 , 000 parts by weight ethyl alcohol , and 1 , 000 to 5 , 000 parts of citric acid by weight . a formulation containing from about 1 . 0 to about 40 . 0 parts by weight of 10 , 11 - methylenedioxy camptothecin in 1 , 000 to 10 , 000 part of nmp further comprising between about 1 , 000 to 5 , 000 parts of an alcohol , about 100 to 5 , 000 parts by weight of an pharmaceutically acceptable acid and about 1 , 000 to 10 , 000 parts of polyethylene glycol 400 . suitable alcohols include ethyl alcohol , and benzyl alcohol . suitable acids for this formulation include citric acid , hydrochloric acid or phosphoric acid . in a preferred embodiment 1 to about 20 parts of 10 , 11 - methylenedioxy by weight is formulated in 1 , 000 to 10 , 000 parts of nmp , 1 , 000 to 10 , 000 parts of peg - 400 , 1 , 000 to 5 , 000 parts by weight ethyl alcohol , and 1 , 000 to 5 , 000 parts of citric acid by weight . a formulation containing from about 1 . 0 to about 40 . 0 parts by weight of 10 - bromo camptothecin in 1 , 000 to 10 , 000 part of nmp further comprising between about 1 , 000 to 5 , 000 parts of an alcohol , about 100 to 5 , 000 parts by weight of an pharmaceutically acceptable acid and about 1 , 000 to 10 , 000 parts of polyethylene glycol 400 . suitable alcohols include ethyl alcohol , and benzyl alcohol . suitable acids for this formulation include citric acid , hydrochloric acid or phosphoric acid . in a preferred embodiment 1 to about 20 parts of 10 - bromo camptothecin by weight is formulated in 1 , 000 to 10 , 000 parts of nmp , 1 , 000 to 10 , 000 parts of peg - 400 , 1 , 000 to 5 , 000 parts by weight ethyl alcohol , and 1 , 000 to 5 , 000 parts of citric acid by weight . one of the key discoveries in the present invention is the unexpectedly high solubility of hlcd in n - methyl - 2 - pyrrolidinone ( nmp ). n - methyl - 2 - pyrrolidinone is an organic liquid excipient and is also known as 1 - methylpyrrolidinone , n - methyl - 2 - pyrrolidinone , 1 - methyl - 5 - pyrrolidinone , methylpyrrolidinone , n - methyl pyrrolidinone , methylpyrrolidinone , n - methylpyrrolidone , n - methyl - 2 - pyrrolidone , m - pyrol , and nmp . nmp exhibits a high degree of physiologic safety in mammals with the following ld50 values : ( rat ) oral -- 7000 mg / kg , intraperitoneal -- 2472 mg / kg , intravenous -- 2266 mg / kg , ( mice ) oral -- 7725 mg / kg , intraperitoneal -- 4429 mg / kg , intravenous -- 3605 mg / kg , ( rabbit ) skin -- 8000 mg / kg ( registry of toxic effects of chemical substances , 1983 - 84 supplement , page 1628 ). nmp has been used to formulate etoposide ( etoposide , u . s . pat . no . 4 , 772 , 589 ) and acridine derivatives ( m - amsa , u . s . pat . no . 5 , 034 , 397 ). etoposide and acridine derivatives ( 1 ) are anticancer drugs ; ( 2 ) are chemically unrelated to hlcd ; ( 3 ) are more water soluble than hlcd ; and ( 4 ) exert their antitumor effects by vastly different mechanisms than hlcd . nmp has also been used for oral formulations of the antibiotic clarithromycin ( clarithromycin , wo patent # 9 , 014 , 094 ) and other drugs . nmp is a key excipient of the instant invention which allows an exceptionally high degree of drug solubility of hlcd ( range 1 mg / ml to 40 mg / ml ) in nmp as a solution or suspension . an hlcd solution comprising nmp with or without other combinations of excipients described herein , which can be diluted with a parenteral vehicle such as sterile injectable water usp , 5 % dextrose solution for injection usp or 0 . 9 % sodium chloride solution for injection usp , such that the amount of hlcd dissolved in the diluted infusion is from about 0 . 001 mg / ml to about 1 . 0 mg / ml , is taught in the present invention . the inventors have discovered that hlcd show remarkably high solubility in nmp compared to other common pharmaceutical solvents such as water , ethanol , benzyl alcohol , propylene glycol , peg 300 , peg 400 , dimethylisosorbide or dimethylacetamide ( table 5 ). this high solubility of hlcd in nmp makes nmp a unique and highly useful pharmaceutical solvent for making useful solutions or suspensions of hlcd . ______________________________________solubility of camptothecin in various solventssolvent concentration , mg / ml______________________________________milli - q water 0 . 0002ethanol 0 . 051benzyl alcohol 1 . 674propylene glycol 0 . 281peg 300 0 . 706dimethylisosorbide 0 . 928dimethylacetamide 5 . 000n - methyl - 2 - pyrrolidinone ( nmp ) & gt ; 15 . 000 ( range 15 - 20 ) ______________________________________ nmp is inert with respect to undesirable chemical reactions with hlcd and is therefore a highly useful excipient to create solutions of hlcd in the lactone form . further utility of nmp in the present invention is the discovery that nmp allows the introduction of additional excipients which further improve the overall utility of the hlcd dissolved in the nmp solution in a manner which are of additional benefit for parenteral or oral administration to human patients with cancer . the hlcd solution or suspension is prepared by mixing the desired components with nmp and adding a pharmaceutically acceptable acid to adjust the ph to 3 - 5 . the following references may facilitate understanding or practice of certain aspects of the present invention . inclusion of a reference in this list is not intended to and does not constitute an admission that the reference represents prior art with respect to the present invention . ______________________________________u . s . patent4 , 545 , 880 10 / 85 miyasaka et al . 4 , 473 , 692 9 / 84 miyasaka et al . 4 , 778 , 891 10 / 88 tagawa et al . 5 , 061 , 800 10 / 91 miyasaka et al . 4 , 772 , 589 9 / 88 kaplan et al . 5 , 034 , 397 7 / 91 kaplan et al . world patent9 , 014 , 094 11 / 90 hui et al . ______________________________________ barilero et al ., simultaneous determination of the camptothecin analogue cpt - 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( eds ): anticancer agents based on natural product models , san diego , calif ., academic press , 1980 , 417 - 436 . wall , m . e . et al ., plant antitumor agents : synthesis and structure activity of novel camptothecin anaglogs . j . med . chem ., 36 : 2689 - 2700 ( 1993 ). westergaard et al ., the mechanism whereby bile acid micelles increase the rate of fatty acid and cholesterol uptake into the intestinal mucosal cell . journal of clinical investigation , 58 : 97 - 108 ( 1976 )). the foregoing description has been directed to particular embodiments of the invention in accordance with requirements of the patent statutes for the purposes of illustration and explanation . it will be apparent , however , to those skilled in this art , that many modifications , changes and variations in the claimed antitumor compositions , solutions , methods of administration of the antitumor compositions set forth will be possible without departing from the scope and spirit of the claimed invention . it is intended that the following claims be interpreted to embrace all such modifications and changes .