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Biomedical subjects

Y W Chien

Publications and source records attributed to Y W Chien.

At least 73 records · Page 4Linked to original sources
PubMed1987

Atrial natriuretic peptide increases resistance to venous return in rats.

To examine mechanisms by which administration of atrial natriuretic peptide (ANP) decreases venous return, we compared the hemodynamic effects of ANP (0.5 microgram X min-1 X kg-1), furosemide (FU, 10 micrograms X min-1 X kg-1), and hexamethonium (HEX, 0.5 mg X min-1 X kg-1) with those of vehicle (VE) in anesthetized rats. Compared with VE, ANP reduced mean arterial pressure (106 +/- 4 vs. 92 +/- 3 mmHg; P less than 0.05), central venous pressure (0.3 +/- 0.3 vs. -0.7 +/- 0.2 mmHg; P less than 0.01), and cardiac index (215 +/- 12 vs. 174 +/- 10 ml X min-1 X kg-1; P less than 0.05) and increased calculated resistance to venous return (32 +/- 3 vs. 42 +/- 2 mmHg X ml-1 X min X g; P less than 0.01). Mean circulatory filling pressure, distribution of blood flow between splanchnic organs and skeletal muscles, and total peripheral resistance remained unchanged. FU increased urine output similar to that of ANP, yet produced no hemodynamic changes, dissociating diuresis, and decreased cardiac output. HEX lowered arterial pressure through a reduction in total peripheral resistance without altering cardiac output or resistance to venous return. The results confirm previous findings that ANP decreases cardiac output through a reduction in venous return and suggest that this results partly from increased resistance to venous return and not from venodilation or redistribution of blood flow.

Animals↗
PubMed1987

Intranasal drug delivery for systemic medications.

This article is designed to provide a critical literature review on the scientific advances in intra- and transnasal drug delivery for systemic medication. The article discusses the fundamentals, developmental concepts, and biomedical assessment of the transnasal administration of systemically effective drugs which are either easily inactivated when taken orally, due to the extensive hepatic first-pass elimination, or too large in molecular size to be absorbed efficiently, except by i.v. administration.

Absorption↗
PubMed1987

Nonparenteral administration of peptide and protein drugs.

Peptides/proteins are an important class of drugs which are usually administered by parenteral route. In recent years, pharmaceutical research has been directed towards developing a nonparenteral route of delivery of peptide/protein drugs. These studies report that it may be possible to administer the peptides/proteins especially insulin, by nasal, buccal, rectal, or even transdermal route. Therefore, there is a great potential for future development of a nonparenteral route of delivery of peptide/protein drugs. The primary objective of this review is to report the present status of research involving nonparenteral administration of macromolecular peptides/proteins, with special emphasis on insulin.

Administration, Cutaneous↗
PubMed1984

Long-term controlled navel administration of testosterone.

Male fertility has reportedly been regulated by the long-term, continuous administration of testosterone. To deliver the testosterone at a controlled rate for a month or longer, a bandage-type, testosterone-releasing, disk-shaped device was developed. In vitro drug elution studies demonstrated that a constant release profile of testosterone was achieved. In vivo studies in rhesus monkeys with the medicated device directly overlaying the navel for 46 d, yielded a fairly steady plasma level and also a constant urinary excretion rate for 32 d. A greater systemic bioavailability (more than twofold) was achieved as compared with drug disposition directly onto the navel or via the placebo device (i.e., drug is deposited onto the prefabricated placebo device). A fairly constant cumulative urinary recovery profile was achieved for longer than 1 month, in which greater than 90% of the dose was administered. The in vitro and in vivo relationship was analyzed and discussed.

Administration, Topical↗
PubMed1984

Intravaginal controlled administration of flurogestone acetate I: Development of a stability-indicating liquid chromatographic method and stability kinetics of flurogestone acetate.

Flurogestone acetate is a synthetic progestin useful for estrus synchronization in sheep. The estrus synchronization is achieved by inserting the drug-impregnated vaginal sponge in the sheep for up to 15 d, during which time flurogestone acetate is administered continuously by intravaginal absorption to suppress estrus and ovulation. The sponge is then withdrawn to regain estrus within 2-4 d. A review of the literature suggests that the analytical methods currently available are not specific, sensitive, and rapid enough. A stability-indicating high-performance liquid chromatographic method was developed, which is capable of characterizing the stability kinetics of flurogestone acetate under various environmental conditions and quantifying the release and absorption profiles of the drug from the vaginal sponges.

Animals↗
PubMed1984

Intravaginal controlled administration of flurogestone acetate II: Development of an in vitro system for studying the intravaginal release and permeation of flurogestone acetate.

A relatively simple and easily constructed in vitro system was developed for studying the mechanism of release and intravaginal absorption of flurogestone acetate from vaginal sponges. The stability-indicating high-performance liquid chromatographic method developed earlier was used to provide a rapid, reproducible, and sensitive assay. The in vitro intravaginal release/permeation system developed was capable of determining the rate of flurogestone acetate release from vaginal sponges and, simultaneously, the rate of absorption through the vaginal wall. The design, calibration, and applicability of the system, and the release and absorption profiles of the drug from vaginal sponges in this system are discussed.

Absorption↗
PubMed1984

Pharmaceutical considerations of transdermal nitroglycerin delivery: the various approaches.

When formulated as a sublingual or an oral sustained-release dosage form, nitroglycerin has certain shortcomings, i.e., decreased duration of antianginal action and extensive hepatic first-pass elimination, which limit its efficacy. The finding that administration of nitroglycerin in the form of topical ointment decreases the extent of hepatic first-pass elimination and increases the duration of therapeutic activity has pointed the way to the possibility of developing a more effective transdermal drug delivery device. Three such devices are the Nitrodisc , Nitro-Dur, and Transderm -Nitro systems. All three systems generate effective plasma drug levels within 30 minutes and maintain steady-state drug plasma levels as follows: the 16 cm2 Nitrodisc at 280.6 +/- 18.7 pg/ml for 32 hours; the 20 cm2 Nitro-Dur at 201.4 +/- 60.7 pg/ml for 24 hours; and the 20 cm2 Transderm -Nitro system at 209.8 +/- 22.8 pg/ml for 24 hours. In vitro studies show that the drug penetrates the skin with zero-order kinetics in all three systems, the rate for Nitrodisc being 20% greater than that of the other systems. When the daily nitroglycerin dose is calculated in terms of skin permeation rate and the device's surface area, the three transdermal systems become clinically interchangeable.

Administration, Oral↗
PubMed1984

Abnormal leucocyte sodium transport in Chinese patients with essential hypertension and their normotensive offsprings.

We studied changes in intracellular electrolytes and the rate constant of 22Na efflux from isolated leucocytes in Chinese patients with essential hypertension and their normotensive offsprings. The hypertensives had an increase of sodium content and a reduction of the total or ouabain-sensitive 22Na efflux from leucocytes. The normotensives born of hypertensive parents showed lower sodium content, higher potassium content and reduced rate constant of ouabain-insensitive 22Na efflux from leucocytes. The results suggest that the inhibition of cell sodium pump activity may be a marker of essential hypertension. Abnormal cell sodium transport observed in normotensives with family history of hypertension may have some etiological linking with the inheritance of hypertension.

Adult↗
PubMed1982

Medicated tampons: intravaginal sustained administration of metronidazole and in vitro-in vivo relationships.

The technical feasibility of utilizing tampons as a drug delivery system for prolonged intravaginal drug administrations was studied. Several commercially available brands of tampons were examined. The methodology for the incorporation of various doses of metronidazole, an antitrichomonas agent, in tampons was described. The sustained-release profile of metronidazole from these medicated tampons was characterized. Intravaginal administration of metronidazole via the medicated tampons was investigated in rhesus monkeys and human volunteers, and in vitro-in vivo correlations were established. The biopharmaceutics of intravaginal absorption of metronidazole via medicated tampons was analyzed in comparison with a vaginal solution formulation.

Absorption↗
PubMed1979

Controlled drug release from polymeric delivery devices V: Hydroxy group effects on drug release kinetics and thermodynamics.

The effects of progesterone hydroxylation on silicone matrix drug release kinetics and thermodynamics were investigated. Hydroxylation at positions 11, 17, and/or 21 substantially reduced progesterone release. The magnitude of this reduction depended on the number and position of the hydroxy groups and could be attributed to decreased polymer matrix diffusivity (Dm) and polymer solubility (Cp). Thermodynamically, hydroxy group addition to positions 11 and/or 21 reduced the activation energy for matrix diffusion (Ed,m) but increased the solvation energy for dissolution in silicone polymer (delta HT,m)). Adding an hydroxy group to position 17 increased the Ed,m but decreased the delta HT,m. The overall (Ed,m) + delta H(T,m)) values were relatively constant and independent of hydroxylation.

Delayed-Action Preparations↗
PubMed1978

Functional group contribution of bile salt molecules to partitioning of a quaternary ammonium N,N-dimethyl derivative of propranolol.

A quaternary ammonium N,N-dimethyl derivative of propranolol was extracted from pH 7.4 phosphate buffer into 1-octanol as ion-pairs with 12 different bile salts. The binding number, n, and the extraction constant, Ke, were determined. To obtain group contribution values of the bile salt molecule from the ion-pair extraction data, multiple linear regression analysis by the Free-Wilson technique was applied. The results showed that the fundamental premise of the functional group's contribution to the ion-pair extraction is valid. The functional groups of counterions contribute to the partitioning of the ammonium compound independently and additively in this system.

Bile Acids and Salts↗