Document Detail

Thermoresponsive drug delivery using liquid crystal-embedded cellulose nitrate membranes.
MedLine Citation:
PMID:  16877309     Owner:  NLM     Status:  MEDLINE    
The aim of this study was to investigate the use of thermotropic liquid crystalline (TLC) blends of 4-pentyl-4'-cyanobiphenyl (K15) and 4-heptyl-4'-cyanobiphenyl (K21) with appropriate nematic to isotropic phase temperature (Tn - i) just above body temperature as a temperature-modulated drug permeation system. Using differential scanning calorimetry (DSC) we showed that the phase transition temperature (Tn - i) of K15 and K21 were 34.2 degrees C and 41.5 degrees C respectively. However, the thermogram of K15 and K21 blends with different ratios was shown to be a single endothermic peak similar to that of pure TLCs. K15 and K21 blends did not behave as a physical blend of two thermotropic liquid crystals with different Tn - i. However, they are rather mixed together in such ways that behave like a single unit TLC. The Tn - i of these TLC mixtures was linearly proportionate to the ratio of K15:K21. Using appropriate ratio of K15:K21 TLC, a mixture with desirable phase transition temperature was obtained. A triple layer of cellulose nitrate membranes containing a 50:50 mixture of K15 and K21 was used for drug permeation studies. This composite membrane showed good pulsatile permeation of drug molecules in response to temperature changes below and above the Tn - i of the K15 and K21 blends in a reproducible and reversible manner. Paracetamol and methimazole were chosen as hydrophobic and hydrophilic drug models, respectively. Methimazole permeability through the TLC membrane was much higher (36.0 x 10(-5) cm/s) at temperatures above the phase transition temperature of liquid crystal blends than that (7.2 x 10(-5) cm/s) at temperatures below the phase transition temperature of liquid crystal blends (38.1 degrees C).
Rassoul Dinarvand; Elham Khodaverdi; Fatemeh Atyabi; Mohammad Erfan
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Drug delivery     Volume:  13     ISSN:  1071-7544     ISO Abbreviation:  Drug Deliv     Publication Date:    2006 Sep-Oct
Date Detail:
Created Date:  2006-07-31     Completed Date:  2006-11-02     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  9417471     Medline TA:  Drug Deliv     Country:  United States    
Other Details:
Languages:  eng     Pagination:  345-50     Citation Subset:  IM    
Department of Pharmaceutics, Faculty of Pharmacy, Tehran University of Medical Sciences, Tehran, Iran.
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MeSH Terms
Acetaminophen / pharmacokinetics
Analgesics, Non-Narcotic / pharmacokinetics
Antithyroid Agents / pharmacokinetics
Biphenyl Compounds / chemistry
Body Temperature / physiology*
Calorimetry, Differential Scanning
Collodion / chemistry*
Delayed-Action Preparations / chemistry,  pharmacokinetics*
Liquid Crystals / chemistry*
Membranes, Artificial
Methimazole / pharmacokinetics
Molecular Weight
Nitriles / chemistry
Phase Transition
Reproducibility of Results
Reg. No./Substance:
0/4-heptyl-4'-cyanobiphenyl; 0/Analgesics, Non-Narcotic; 0/Antithyroid Agents; 0/Biphenyl Compounds; 0/Delayed-Action Preparations; 0/Membranes, Artificial; 0/Nitriles; 103-90-2/Acetaminophen; 40817-08-1/4-cyano-4'-pentylbiphenyl; 60-56-0/Methimazole; 9004-70-0/Collodion

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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