• Journal of Pharmaceutical Investigation
• /
• 제24권3호spc1호
• /
• pp.59-66
• /
• 1994

The objective of this study was to determine the influence of drug lipophilicity on the extent of ocular and systemic absorption following topical solution instillation in the pigmented rabbit. ${\beta}-Blockers$ of various lipophilicity were chosen as model drugs, $25\;{\mu}l$ of a 15 mM drug solution in isotonic pH 7.4 buffer was instilled, and ocular tissue and plasma drug concentrations were monitored. Ocular absorption was apparently increased in all eye tissues, but non-corneal absorption ratio was decreased by increasing of drug lipophilicity. Systemic bioavailability was ranged from 61% for atenolol to 100% for timolol, and at least 50% of the systemically absorbed drug reached the blood stream from the nasal mucosa. Occluding the nasolacrimal duct for 5 min reduced the extent of systemic absorption of timolol and levobunolol, but did not do so for atenolol and betaxolol. Taken together, the ocular absorption of topically applied ophthalmic drugs would be modest for lipophilic drugs. By contrast, the systemic bioavailability would be modest for drugs at the extremes of lipophilicity, and the nasal contribution to systemically absorbed drug diminished with increasing of drug lipophilicity.

• Archives of Pharmacal Research
• /
• 제8권3호
• /
• pp.177-186
• /
• 1985

Effect of food on the absorption characteristics of oral rifampicin was studied in the fasted rats. Rifampicin dissolved in a new cosolvent was also injected to the rats intravenously, and the pharmacokinetic analysis was performed to explain the effect of food on the gastrointestinal absorption of rifampicin. Rifampicin was absorbed rapidly and completely in the fasting state. Food had a profound effect on the gastrointestinal absorption of rifampicin, i. e., bioavailability and the extent of absorption were decreased to less than one-third of the fasting state in the postprandial state. Food seemed to imhibit the absorption and reabsorption of rifampicin in the gastrointestinal tract, but not the absorption rate constant. Hepatobiliary excretion seemed to be the major route of elimination, since the renal clearance accounted for only 8 % of the systemic clearance. Nevertheless, first-pass effect was negligibly small and most of rifampicin absorbed could reach systemic circulation. Serum concentration change of oral rifampicin on multiple dosing differed markedly in the fasting and postprandial state, which suggested the need of careful adjustment of dosage regimen in both states.

• Archives of Pharmacal Research
• /
• 제17권5호
• /
• pp.364-370
• /
• 1994

A microscopic mass balance approach has been developed to estimate the extent and rate of absorption for camier-mediated comounds. For the case competitive inhibition in the presence of an inhibitor which shares the same camier, the fraction dose absorbed (F) and absorption rate constant ($K_a$) of a drug can be calculated from its concentration profile in the intestinal lumen. Absorption parameters obtained by single-pass perfusion experiments were used in the simultaion of the absorption of some aminopenicilins. Predicted fractions dose absorbed and absorption rate constants of ampicilin and amoxicilin were significantly reduced in the presence of a 6-times higher molar dose of cyclacilin. The drug-drug interactions on the competitive absroption of camier-mediated compounds were determined with regard to F and $K_a$. Predicted decreases in F for some aminopenicilins corrlated well with decrease in the urinary recovery in humans reported in the literature. Predicted decrease in the mean absorption rate constant ($\barK_a$) explain the delays in the time of peak plasma concentration ($T_{max}$) reported in humans.

• 대한가정학회지
• /
• 제25권2호
• /
• pp.31-38
• /
• 1987

This paper aims to examine the velocity of water absorption of cotton, hemp, and T/C fabrics sized by rice, wheat, potato, corn flour and pp.V.A.. Experimental variables such as the concentration of sizing agents, the moisture regain of unsized fabrics and the ironing temperature showed the following results. 1. When the fabrics were sized, the velocity of water absorption increased according to the order of corn, rice, potato, wheat flour and pp.V.A. for cotton fabrics, of corn, potato, rice, wheat flour and pp.V.A. for hemp fabrics, and of corn, wheat, rice, potato flour and pp.V.A. for T/C fabrics; corn flour showed the highest velocity of water absorption and pp.V.A. did the lowest among all the others mentioned above. 2. The higher fabric density, the higher velocity of water absorption. The finer the count of fabric yarn, the higher velocity of water absorption. 3. The material of sized fabrics most affected the velocity of water absorption than other factors of those. 4. To a certain extent, the higher the concentration of sizing agent, the higher the velocity of water absorption. 5. The fabrics with moisture regain of 20% before sizing showed the highest velocity of water absorption. 6. The ironing temperature after sizing fabrics mentioned below showed the highest velocity of water absorption; 180$^{\circ}C$ for cotton, 200$^{\circ}C$ for hemp, and 160$^{\circ}C$ for T/C fabrics.

• Journal of Pharmaceutical Investigation
• /
• 제22권1호
• /
• pp.49-54
• /
• 1992

This study was carried out for the purpose of developing an effective temazepam soft elastic gelatin capsule (softgel) which exhibits an excellent bioavailability and of comparing the rate and extent of absorption of temazepam from the marked elixir and prepared softgel using hydrophilic liquid such as polyethylene glycol 400 as a suspending agent by rotary die method. Both softgel and elixir containing 3 mg of temazepam were given to 7 healthy male New Zealand White rabbits in a single oral dose cross-over study. Plasma temazepam concentrations were measured by HPLC. The mean peak concentrations of temazepam following a single oral dosing as softgel and elixir dosage form were 13.84 and 13.25 ng/ml, respectively. And the mean time to peak concentration was 1.29 hr for the softgel and 1.07 hr for the elixir. There was no significant difference in the extent of drug absorption (AUC) for the two different dosage froms (p>0.05). While the softgel exhibited mean lag time of 0.63 hr, the elixir did not show any lag time. Statistical moment parameters such as the mean residence time and variance of the mean residence time did not differ significantly for the two formulations.

• 약학회지
• /
• 제23권2호
• /
• pp.81-94
• /
• 1979

Rifampicin-polyvinylpyrrolidone coprecipitates were prepared by the solvent method to increase the solubility and dissolution rate, thereby improving absorption of rifampicin. It was found that the solubility and dissolution rate were greater with the 1 : 5 (w/w) coprecipitate than with the pure drug, physical mixtures or coprecipitates of any other ratio of the two components. The blood concentration data in non-fasted rats showed that the extent of absorption of rifampicin were significantly enhanced following the oral administration of the 1 : 5 coprecipitate; The area under the serum concentration curve (0-8hr) was 1.3 times greater with the 1 : 5 coprecipitate than with the pure drug. The blood concentration reached its peak (4. 38$\pm$1.36mcg/ml) within two hours in the case of oral administration of the 1 : 5 coprecipitate and, on the other hand, it reached the maximum (3.77$\pm$0.90mcg/ml) after four hours of oral administration of the pure drug. It was observed that there was no significant difference between the 1 : 5 coprecipitate and the pure drug in the extent and rate of absorption of rifampicin when fasted rats were used. When the 1 : 5 coprecipitate was orally administered to human subjects 20 minutes after meal, it was found that the blood concentration reached the maximum after one hour; in the case of the pure drug, it reached its peak after four hours.

• 대한가정학회지
• /
• 제23권1호
• /
• pp.11-17
• /
• 1985

This paper aims to examine the variety of the absorption of cotton, T/C and hemp fabrics seperately seperaterly sized by rice, wheat, potato, corn flour and pp.V.A.. Experimental variables occurring in the concentration of sizing agents, the water content of unsized fabrics and an iron temperature show the following results, 1. When fabrics sized, the rate of absorption increases according to the order of rice, corn, pp.V.A., potato, wheat flour for cotton fabrics, of rice, corn, pp.V.A., wheat, potato flour for hemp fabrics and of the rice, pp.V.A., potato, corn, wheat flour for T/C fabrics : rice flour shows an absorption rate highest among all the others mentioned above. 2. To a certain extent, the stronger the concentration of sizing agents, the higher the rate of absorption. 3. The higher fabrics density, the higher absorption rate. 4. The structure and hydrophilic property of the sized fabrics affect the rate of absorption. 5. The fabrics with water content of 20% before sizing it shows the rate of absorption highest. 6. An iron temperature after sizing fabrics shows the rate of absorption highest at the properest at the properest one : $180^{\circ}C$ for cotton, $150^{\circ}C$ for T/C and $200^{\circ}C$ for hemp fabrics.

• 대한약학회:학술대회논문집
• /
• 대한약학회 2002년도 Proceedings of the Convention of the Pharmaceutical Society of Korea Vol.2
• /
• pp.411.3-412
• /
• 2002

On the basis of recognizing that physicochemical properties (lipophilic/hydrophilic), intestinal absorption clearance and pharmacokinetic characteristics of drug are the fundamental parameters controlling the rate and the extent of drug absorption, the biopharmaceutics classification system for the correlation between drug lipid- solubility and intestinal absorption clearance is proposed. (omitted)

• Fibers and Polymers
• /
• 제5권2호
• /
• pp.95-104
• /
• 2004

A series of superabsorbents based on acrylic acid (AA), sodium acrylate, 2-acrylamido-2-methylpropane sulphonic acid, N,N'-methylene bis-acrylamide (MBA) were prepared by inverse suspension polymerization. These hydrogels were further crosslinked on the surface with polyethylene glycol-600 (PEG-600). The water absorbency or swelling behaviors for these xerogels in water and 0.9% saline solutions, both under free condition and under load were investigated. Absorption characteristics of these hydrogels were found to depend on nature and concentration of crosslinker in the system. It was also found that the saline absorption was significantly improved as the incorporation of AMPS in the polymer was increased. The surface crosslinking introduced in the polymers was found to improve the absorption under load characteristics without lowering the free water absorption capacities of the polymer to a considerable extent.

• Archives of Pharmacal Research
• /
• 제18권6호
• /
• pp.427-433
• /
• 1995

A microscopic mass balance approach has hsown that the initial saturation (Is), absorption number (An), dose number (Do), and dissolution number (Dn) are four fundamental dimensionless parameters that can be used to estimate the fraction dose absorbed (F)l of suspensions of poorly soluble drugs in humans. The dissolution number of a drug increases with decreasing its particle size. The effect of micronization on F for suspensions was investigated in terms of Dn. About 90% of maximal F can be achieved at $Dn{\approx}2$. Increasing the solubility of a drug results in better oral absorption through increasing Dn and decreasing the solubility of a drug results in better oral absorption through increasing Dn and decreasing Do. The fractions dose absorbed of digoxin, griseofulvin, and benoxaprofen agree with predicted F values sorbed by reducing particle size, while absorption of drugs with high Do and low Dn is limited by solubility and requires higher solubility to enhance the fraction dose absorbed in addition to micronization. Solubility at the physiological pH should be used for the estimation of the fraction dose absorbed.