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Biomedical subjects

K Danjo

Publications and source records attributed to K Danjo.

29 records · Page 2Linked to original sources
PubMed1995

Release of lidocaine from polymer film dosage forms.

We investigated the in vitro drug release from mixed polymer films using lidocaine (LC), which is poorly water-soluble. The mixed polymer films consisted of various ratios of hydroxypropylcellulose (HPC) and hydroxypropylmethylcellulose phthalate (HPMCP). The effects of the presence glycyrrhizic acid (GL) or polyethylene glycol (PEG) in the films upon LC release were also studied. LC crystallinity decreased in the polymer film and this decrease was remarkable in the presence of GL, resulting in an amorphous state. During the initial stage, drug release was regarded as a zero-order dissolution. The apparent release rate constant, ka, varied with the ratios of the two polymers and the amount of additives as well as with the pH of the test solution. The results indicated that GL enhanced the dissolution rate of LC from mixed polymer films, which may be due to the formation of an amorphous state. On the other hand, since PEG is a surfactant, the enhanced wettability of the polymer by the buffered solutions may have caused the increased dissolution rate.

Calorimetry, Differential Scanning↗
PubMed1994

Release of isosorbide dinitrate from polymer film dosage forms and absorption of this drug through the oral mucosa of rats.

In vitro release tests and in vivo absorption measurements of oral cavity dosage forms of isosorbide dinitrate (ISDN) prepared from mixed polymer film systems were conducted. Hydroxypropylcellulose (HPC) and hydroxypropylmethylcellulose phthalate (HPMCP) were used to make the films, and the tests were conducted with films made from various ratios of these two polymers. The effects of the addition of the accelerator glycyrrhizic acid (GL), on dissolution and absorption were also examined. The mean dissolution time (MDT) in the in vitro dissolution tests varied with the nature of the polymers and drug, as well as with the pH of the testing solution. The MDT for the polymer film system with GL was smaller than that without GL. In the in vivo absorption tests using rats, the absorption of ISDN through the oral mucosa was observed in all the systems. In the mixed polymer film systems, the mean residence time (MRT) increased with increasing the ratio of HPMCP/HPC. The values of the area under the curve (AUC) for the systems with GL was larger than for those without GL. A good correlation was demonstrated between the absorption rate constant, ka and the dissolution rate constant, kd.

Absorption↗
PubMed1987

Limits to the concept of solid-state stability.

Recently published data about the decomposition of propantheline bromide in the presence of moisture resulted in a general, two-variable, phenomological equation relating the decomposition to the relative humidity and temperature. The true curve, however, is biphasic, since complete liquefaction occurs at some time point. This article deals with the development of a theoretical equation relating decomposition time, temperature, and relative humidity during the solid-state stage (i.e., during the period when solid is still present in the system).

Drug Stability↗
PubMedDate not supplied

Applicability of chemiluminescence to assess the degree of operative stress in patients undergoing spinal surgery.

This study examined the applicability of luminol-dependent chemiluminescence (CL) response of neutrophils to assess the degree of stress of spinal surgery by measuring the capacity of circulating neutrophils to produce reactive oxygen species and the levels of serum cytokines: interleukin(IL)-1beta, IL-6, IL-8, tumour necrosis factor (TNF)-alpha and granulocyte colony stimulating factor (G-CSF). Ten male patients underwent spinal surgery. Peripheral blood samples, collected before and after the operation and the next morning, were used for measuring the CL response of neutrophils stimulated with opsonized zymosan and measuring the levels of serum cytokines. The operative stress induced leukocytosis, particularly granulocytosis, and increased serum IL-6 and G-CSF significantly. However, there was no significant change in the luminol-dependent CL response of neutrophils or the levels of serum IL-1beta, IL-8 and TNF-alpha throughout the experimental period. These results suggest that, at least in the early postoperative period, operative stress does not prime the circulating neutrophils, and thus the CL response of neutrophils is not appropriate to assess the degree of stress of spinal surgery.

Adult↗