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  • 1
    Electronic Resource
    Electronic Resource
    Thermodynamics of partitioning and efflux of phenothiazines from liposomes (1981)
    Springer
    The journal of membrane biology 58 (1981), S. 181-189 
    Details
    ISSN: 1432-1424
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Summary The partitioning of nine phenothiazines between dimyristoylphosphatidylcholine (DMPC) liposomes and 0.9% wt/vol saline at pH 6 has been studied both below and above the phase transition temperature (T c ) of the phospholipid. Higher partitioning was observed aboveT c . Both the entropy and enthalpy of partitioning were positive below and aboveT c , and a linear relationship between the entropy and enthalpy has been derived. In general, the partitioning and transport of alkylaminophenothiazines in DMPC liposomes over the temperature range of 5 to 40°C is entropically controlled. The entropies and enthalpies of partitioning of various groups in the phenothiazine structure have been calculated. No relationship was found between particle size of the DMPC liposomes and the equilibrium partition coefficient at 25°C. However, the particle size of liposomes did increase with increasing acyl chain length of the phospholipid. Using differential scanning calorimetry, the enthalpy and entropy of transition of the DMPC liposomes in the absence and presence of phenothiazines has been calculated. The temperature dependence of the first-order rate constant of trimeprazine tartrate transport in DMPC liposomes was investigated and was found to be maximum at theT c of the phospholipid.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01870904
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  • 2
    Electronic Resource
    Electronic Resource
    The in Vitro Characterization and Biostability of 99mTc-Dextran and Its Accumulation Within the Inflamed Paws of Adjuvant-Induced Arthritic Rats (1995)
    Springer
    Pharmaceutical research 12 (1995), S. 588-593 
    Details
    ISSN: 1573-904X
    Keywords: 99mTc-dextran ; plasma and biostability in rats ; RES uptake ; targeting of inflammation ; adjuvant-induced arthritis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The in vitro and in vivo stability in normal and adjuvant-induced arthritic rats of 99mTc-dextrans (10, 40 and 500 kDa) have been investigated. The circulation half-lives were molecular weight dependent, with 10 and 40 kDa fractions being cleared relatively rapidly due to their ability to cross the glomerular basement membrane. The 500 kDa dextran was eliminated more slowly although 79% had been removed from the circulation 4 h post injection which probably was due to its degradation by dextranases and subsequent glomerular excretion. Dextran accumulation by the RES was found to be similar for all molecular weight preparations with no significant differences found. The sequestration of the dextrans by tissues of the RES (liver, spleen and lung) was independent of clearance rate. No differences were seen between normal and arthritic groups. Accumulation of the polymers by inflamed paws greatly exceeded that of normal paws for the 10 kDa (5-fold) and 500 kDa (6-fold) although no differences were seen with the 40 kDa dextran.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1016218400171
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  • 3
    Electronic Resource
    Electronic Resource
    The Influence of Liposomal Encapsulation on Sodium Cromoglycate Pharmacokinetics in Man (1989)
    Springer
    Pharmaceutical research 6 (1989), S. 633-636 
    Details
    ISSN: 1573-904X
    Keywords: sodium cromoglycate ; liposome ; liposomal ; drug delivery system ; pulmonary drug delivery
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The pharmacokinetics of pulmonary-administered sodium cromoglycate (SCG) has been studied in five healthy volunteers. SCG, 20 mg, was inhaled as a solution and encapsulated in dipalmitoyl phosphatidylcholine/cholesterol (1:1) liposomes. Liposomal SCG produced detectable drug levels in plasma from four volunteers taken 24 and 25 hr after inhalation. Inhaled SCG solution, although producing peak plasma levels more than sevenfold greater than liposomal drug, was not detectable in 24-hr samples from any volunteer. The decline in plasma levels following inhalation of liposomal SCG (reflecting the absorption phase) was best described by a biexponential equation. The two absorption rate constants differed by more than an order of magnitude. The rapid absorption phase was probably due to free or surface-adsorbed SCG in the liposomal formulation, since the absorption rate constant for this phase did not differ significantly from the absorption rate constant for SCG in solution. The phase of slow drug absorption may then be attributed to absorption of drug released from vesicles. The data indicate that encapsulation of SCG prior to pulmonary administration prolonged drug retention within the lungs and altered its pharmacokinetics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1015917918130
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  • 4
    Electronic Resource
    Electronic Resource
    The Thermodynamics of Partitioning of Phenothiazines between Phosphate Buffer and the Lipid Phases of Cyclohexane, n-Octanol and DMPC Liposomes (1985)
    Springer
    Pharmaceutical research 2 (1985), S. 119-124 
    Details
    ISSN: 1573-904X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The partitioning of six phenothiazines was determined between phosphate buffer (pH 6.0) and the lipid phases of cyclohexane, n-octanol and dimyristoyl phosphatidylcholine (DMPC). For DMPC liposomes studies were carried out both below and above the phase transition temperature (Tc) of the liposomes. The partitioning of chlorpromazine hydrochloride between n-octanol and phosphate buffer was both pH and concentration-dependent. A linear relationship between the absolute temperature (T−1) and the logarithm of the equilibrium partition coefficient (ln K) was derived. The temperature dependence of the partition coefficient (K) over the temperature range 20–40° C in cyclohexane and n-octanol, and 5–40° C in DMPC liposomes, permitted the calculation of free-energy (G), enthalpy (H) and the entropy (S) of partitioning. Both the entropy and the enthalpy of partitioning of phenothiazines were positive in the three systems studied. In general, the partitioning of phenothiazines in cyclohexane, n-octanol and DMPC liposomes (both above and below the phase transition temperature (Tc)) is entropically controlled. Correlation was not however found between the free-energy of oil-water partitioning and liposome-water partitioning which may be attributed to the formation of surface associated phenothiazine in high concentrations at the liposome water interface. The concentration dependent partitioning of chlorpromazine in DMPC liposomes may be attributed to the adsorbed fraction of drug.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1016359215869
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  • 5
    Electronic Resource
    Electronic Resource
    Evaluation of Mucoadhesive Polymers in Ocular Drug Delivery. II. Polymer-Coated Vesicles (1992)
    Springer
    Pharmaceutical research 9 (1992), S. 1137-1144 
    Details
    ISSN: 1573-904X
    Keywords: ocular drug delivery ; mucoadhesion ; poly(acrylic acid) ; ocular retention ; liposomes ; tropicamide
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Association of Carbopol 934P and Carbopol 1342 (a hydrophobic modified Carbopol resin) with phospholipid vesicles was assessed by photon correlation spectroscopy and microelectrophoresis at pH 7.4 and 5. The precorneal clearance of the polymer-coated vesicles was compared to that of uncoated vesicles by lacrimal dacryoscintigraphy in the rabbit. The mucoadhesive polymer-coated vesicles demonstrated significantly enhanced precorneal retention compared to noncoated vesicles only at pH 5 (P 〈 0.005). The entrapment and subsequent release of tropicamide from Carbopol 1342-coated and uncoated liposomes were determined in vitro together with an in vivo evaluation of the vesicles formulated at the lower pH. Mucoadhesive polymer-coated vesicles failed to increase significantly the bioavailability of the entrapped tropicamide compared to uncoated vesicles and aqueous solution.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1015891419676
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  • 6
    Electronic Resource
    Electronic Resource
    Evaluation of Mucoadhesive Polymers in Ocular Drug Delivery. I. Viscous Solutions (1991)
    Springer
    Pharmaceutical research 8 (1991), S. 1039-1043 
    Details
    ISSN: 1573-904X
    Keywords: ocular drug delivery ; mucoadhesion ; poly(acrylic acid) ; ocular retention ; pilocarpine ; miosis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The potential of a mucoadhesive polymer as an ophthalmic vehicle is evaluated within the rabbit. Precorneal clearance of a mucoadhesive polymer solution (Carbopol 934P) is compared to that of an equiviscous nonmucoadhesive poly(vinyl alcohol) solution (PVA) and buffer (PBS). The precorneal retention of the Carbopol 934P, as studied by lacrimal dacryoscintigraphy, is shown to be significantly greater (P 〈 0.05) than that of PVA, which, in turn, is significantly greater than that of PBS. The effect of the polymer solution on the bioavailability of pilocarpine is subsequently assessed by measuring the relative miotic response intensities produced by a 1% solution of the drug. Carbopol 934P solution produces a significant increase (P 〈 0.05) in bioavailability as compared to PVA and PBS. The bioavailability from PVA is significantly greater (P 〈 0.05) than that from PBS. Studies evaluating vehicle-drug association indicated no binding of the drug to the polymer.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1015813225804
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  • 7
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    Partitioning and efflux of phenothiazines from liposomes (1980)
    Elsevier
    Details
    Publication Date: 1980-09-01
    Print ISSN: 0006-2952
    Electronic ISSN: 1873-2968
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Published by Elsevier
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  • 8
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    Combined Surface Pressure−Interfacial Shear Rheology Study of the Effect of pH on the Adsorption of Proteins at the Air−Water Interface (2005)
    American Chemical Society
    Details
    Publication Date: 2005-07-09
    Print ISSN: 0743-7463
    Electronic ISSN: 1520-5827
    Topics: Chemistry and Pharmacology
    Published by American Chemical Society
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