ABSTRACT
Three conjugates of thymopentin (TP5), an oligopeptide derived from the thymic hormone thymopoietin, with lipoamino acid (LAAs) have been obtained by solid-phase peptide synthesis. Both linear and dendrimer structures have been prepared to achieve enhanced lipophilicity. After incubation in foetal calf serum the lipophilic conjugates showed a higher stability to hydrolysis with respect to the parent drug. In a preliminary in vitro biological assay, LAA conjugates showed the ability to retain or improve the growth inhibitory activity of the parent peptide against a human lymphoblastoid cell line. The interaction of the prepared conjugates with 1,2-L-alpha-dimiristoylphosphatidylcholine multilamellar liposomes, chosen as a biological membrane model, was studied. The higher lipophilicity of TP5 conjugates was reflected in a better penetration through phospholipid bilayers, whose thermal behaviour was altered in a concentration-dependent way. Such enhanced affinity of TP5-LAA conjugates for this membrane model could anticipate a better interaction with cell membranes and, ultimately, an improved biological activity of compounds compared with the parent pentapeptide.
Subject(s)
Amino Acids/chemistry , Amino Acids/pharmacology , Antineoplastic Agents/chemistry , Antineoplastic Agents/pharmacology , Lipids/chemistry , Lipids/pharmacology , Thymopentin/chemistry , Thymopentin/pharmacology , Anisotropy , Antineoplastic Agents/chemical synthesis , Calorimetry, Differential Scanning , Cell Line , Cell Line, Tumor , Chemical Phenomena , Chemistry, Physical , Chromatography, High Pressure Liquid , Diffusion , Drug Stability , Humans , Hydrolysis , Leukemia-Lymphoma, Adult T-Cell/drug therapy , Leukemia-Lymphoma, Adult T-Cell/pathology , Liposomes , Thymopentin/chemical synthesisABSTRACT
OBJECTIVE: Lorazepam (LZM) is a broadly used tranquillizer for the treatment of anxiety. Tavor is one of the most diffused registered drug products containing LZM. Lots of generic drug products containing LZM have been registered in Italy by several pharmaceutical groups and are present in the Italian market. Due to the wide medical prescription of products containing LZM, it seemed interesting, from a technological and biopharmaceutical point of view, to perform a comparative bioequivalence evaluation of a trade marked and generic tablet formulations containing LZM available in the Italian market. MATERIALS AND METHODS: The trial vas carried out on four preparations, including Tavor (1 mg) as reference product and three generics named A, B and C. In vitro technological parameters (dissolution, uniformity of content, uniformity of weight) and in vivo (pharmacokinetic on rabbit) studies were performed. RESULTS: All the examined brands passed technological tests according the European Pharmacopeia 5th ed. and USP25. Tavor ensures a faster dissolution behaviour than the tree generics in vitro. All the pharmacokinetic parameters were within the prescriptions of EMEA, even if the reference product showed the highest values of AUC0-infinity and of Cmax. CONCLUSIONS: Obtained results show that Tavor ensures a faster dissolution behaviour than the tree generics in vitro. Moreover, considering the pharmacokinetic data, it is possible to suppose that the generics B and C are not able to provide the same therapeutic effect as the reference product.
