title: Synthesis and in vitro evaluation of novel morpholinyl- and methylpiperazinylacyloxyalkyl prodrugs of 2-(6-methoxy-2-naphthyl)propionic acid (Naproxen) for topical drug delivery.
abstract: Various novel morpholinyl- (3a,b) and methylpiperazinylacyloxyalkyl (3c-f) esters of 2-(6-methoxy-2-naphthyl)propionic acid were synthesized and evaluated in vitro for topical drug delivery as potential prodrugs of naproxen (1). Compounds 3a-f were prepared by coupling the corresponding naproxen hydroxyalkyl ester with the morpholinyl- or (4-methyl-1-piperazinyl)acyl acid in the presence of dicyclohexylcarbodiimide (DCC) and 4-(dimethylamino)pyridine (DMAP) and quantitatively hydrolyzed (t(1/2) = 1-26 min) to naproxen in human serum. Compounds 3c-f showed higher aqueous solubility and similar lipophilicity, determined by their octanol-buffer partition coefficients (log P(app)), at pH 5.0 when compared to naproxen. At pH 7.4 they were significantly more lipophilic than naproxen. The best prodrug 3c led to a 4- and 1.5-fold enhancement of skin permeation when compared to naproxen at pH 7.4 and 5.0, respectively. The present study indicates using a methylpiperazinyl group yields prodrugs that are partially un-ionized under neutral and slightly acidic conditions, and thus, a desirable combination is achieved in terms of aqueous solubility and lipophilicity. Moreover, the resulting combination of biphasic solubility and fast enzymatic hydrolysis of the methylpiperazinylacyloxyalkyl derivatives gave improved topical delivery of naproxen.
authors.affiliation: Departments of Pharmaceutical Chemistry and Chemistry, University of Kuopio, P.O. Box 1627, FIN-70211 Kuopio, Finland, and Finncovery Ltd, Kuopio, Finland. jarkko.rautio@uku.fi
authors.forename: J
authors.initials: J
authors.lastname: Rautio
authors.forename: T
authors.initials: T
authors.lastname: Nevalainen
authors.forename: H
authors.initials: H
authors.lastname: Taipale
authors.forename: J
authors.initials: J
authors.lastname: Vepsäläinen
authors.forename: J
authors.initials: J
authors.lastname: Gynther
authors.forename: K
authors.initials: K
authors.lastname: Laine
authors.forename: T
authors.initials: T
authors.lastname: Järvinen
mesh_terms: D000287:Administration, Topical; D000894:Anti-Inflammatory Agents, Non-Steroidal / Q000008:administration & dosage / Q000138:chemical synthesis* / Q000737:chemistry / Q000494:pharmacology; D006801:Humans; D066298:In Vitro Techniques; D009288:Naproxen / Q000008:administration & dosage* / Q000031:analogs & derivatives* / Q000138:chemical synthesis / Q000737:chemistry / Q000494:pharmacology; D010539:Permeability; D010879:Piperazines / Q000008:administration & dosage / Q000138:chemical synthesis* / Q000737:chemistry / Q000494:pharmacology; D011355:Prodrugs / Q000008:administration & dosage / Q000138:chemical synthesis* / Q000737:chemistry / Q000494:pharmacology; D012869:Skin Absorption; D012995:Solubility; D013329:Structure-Activity Relationship
chemical_list: C407567:2-((4-methyl-1-piperazinyl)acetyloxy)ethyl (6-methoxy-2-naphthyl)propanoate; D000894:Anti-Inflammatory Agents, Non-Steroidal; D010879:Piperazines; D011355:Prodrugs; D009288:Naproxen