Reference

The effect of different surface chemical groups on drug binding to liposomes

The effect of different surface chemical groups on drug binding to liposomes. Schlieper, Peter; Steiner, Rudolf (Inst. Pharmakol., Univ. Duesseldorf, Duesseldorf D-4000, Fed. Rep. Ger.). Chem. Phys. Lipids, 34(1), 81-92 (English) 1983. CODEN: CPLIA4. ISSN: 0009-3084. DOCUMENT TYPE: Journal CA Section: 1 (Pharmacology) Section cross-reference(s): 63 The binding of 4 secondary and tertiary amine drugs with local anesthetic activity (propranolol [525-66-6], tetracaine [94-24-6], lidocaine [137-58-6], and procaine [59-46-1]) to liposomes contg. charged surface groups of different chem. compn. was investigated. Binding was detd. by measurement of partition coeffs. and of drug induced zeta potential changes of the liposomes. For propranolol 30% of the total amt. of drug dissolved in phosphatidylcholine is located as protonated form in the liposome surface. Fifty percent of tetracaine and 13% of procaine contribute to the surface charges. Neg. surface charges (phosphatidylserine) facilitate drug binding and drug protonization in the liposome surface. Pos. surface charges (hexadecyltrimethylammonium) prevent the protonization of the drugs. Different chem. groups of single neg. charged phospholipids or of electrostatically neutral lipids have no significant effect on drug binding which proves the binding is not influenced by steric and bulky head group configurations. The drugs interact hydrophobically with the lipid phase in such a way that the drug amine protonizes in the presence of the neg. charged phosphate O of the phospholipid. Hexadecanoic acid [57-10-3] is located deeper within the liposome surface than other neg. charged phospholipids. Correspondingly the drug action is weaker and drug protonization is prevented.

Local anesthesia by percutaneous absorption

Local anesthesia by percutaneous absorption. Part II. Ziegenmeyer, J.; Reuter, N.; Meyer, F. (Inst. Pharmakol. Toxikol., Tech. Univ. Braunschweig, Braunschweig, Ger.). Arch. Int. Pharmacodyn. Ther. 110-82-7 and 17692-39-6 are cas registry numbers of chemicals which are used as reagents here., 224(2), 338-50 (German) 1976. CODEN: AIPTAK. DOCUMENT TYPE: Journal CA Section: 1 (Pharmacodynamics) Cyclohexane [110-82-7] and hexadecane [544-76-3] accelerated the penetration of local anesthetics (lidocaine [73-78-9], fomocaine [17692-39-6], procaine [59-46-1]) through the intact skin of guinea pigs. Dissolved in cyclohexane, the potency of lidocaine was twice that of fomocaine, the latter being more active than procaine. When dissolved in hexadecane, the activity of the local anesthetics was markedly reduced. In combination with 2-butanone [78-93-3], (30% w/w), a solvent without any apparent effect on the permeability of skin, enhanced anesthetic effects are noted. The anesthetic bases, dissolved in dimethyl sulfoxide [67-68-5], produce a much deeper and longer local anesthetic effect than the solns. of their salts. .