title: Interaction of Oxicam NSAIDs with lipid monolayer: anomalous dependence on drug concentration.
abstract: Surface pressure (pi) versus specific molecular area (A) isotherms of Langmuir monolayers of dimyristoylphosphatidylcholine (DMPC) lipid on pure water were studied in pristine form and in presence of three non-steroidal anti-inflammatory drugs, meloxicam (MX), piroxicam (PX) and tenoxicam (TX) in the subphase. Data were taken at three drug/lipid (D/L) ratios of 0.026, 0.05, and 0.1. Integration of drug to the lipid monolayer was measured by the increase in A (Delta A) of DMPC monolayer due to the presence of drugs. All three drugs could be integrated in the monolayer resulting in a positive value of Delta A for D/L ratio of 0.026. Above this D/L value, there is an anomalous, monotonic decrease in Delta A for MX and TX resulting, finally, in negative Delta A values. For PX, however, decrease in Delta A values at D/L of 0.05 is partially compensated at D/L of 0.1. We have tentatively explained these observations by invoking two competing forces in the overall drug-lipid interaction. One of these is an 'in-plane' force that tends to integrate the drug molecule to the plane formed by the lipid monolayer and the other is an 'out-of-plane' force that perturbs the drug and the lipid molecules such that the monolayer plane is no longer well defined.
authors.affiliation: Surface Physics Division, Saha Institute of Nuclear Physics, 1/AF Bidhannagar, Kolkata 700064, India.
authors.forename: Sarathi
authors.initials: S
authors.lastname: Kundu
authors.forename: Hirak
authors.initials: H
authors.lastname: Chakraborty
authors.forename: Munna
authors.initials: M
authors.lastname: Sarkar
authors.forename: Alokmay
authors.initials: A
authors.lastname: Datta
mesh_terms: D000894:Anti-Inflammatory Agents, Non-Steroidal / Q000737:chemistry*; D004134:Dimyristoylphosphatidylcholine / Q000737:chemistry; D004305:Dose-Response Relationship, Drug; D008055:Lipids / Q000737:chemistry; D000077239:Meloxicam; D008563:Membrane Lipids / Q000737:chemistry*; D008567:Membranes, Artificial; D008956:Models, Chemical; D015394:Molecular Structure; D010894:Piroxicam / Q000031:analogs & derivatives* / Q000737:chemistry*; D011312:Pressure; D013499:Surface Properties; D013843:Thiazines / Q000737:chemistry*; D013844:Thiazoles / Q000737:chemistry*; D014867:Water / Q000737:chemistry
chemical_list: D000894:Anti-Inflammatory Agents, Non-Steroidal; D008055:Lipids; D008563:Membrane Lipids; D008567:Membranes, Artificial; D013843:Thiazines; D013844:Thiazoles; D014867:Water; D010894:Piroxicam; D004134:Dimyristoylphosphatidylcholine; D000077239:Meloxicam; C032801:tenoxicam