Release Suspension Research Articles

イブプロフェンマイクロスフェアーを用いたサスペンジョン型経口徐放剤の薬物放出特性と生物学的利用能

The drug release behavior and bioavailability of newly developed controlled release suspensions of ibuprofen were investigated. The suspension was prepared by suspending spherical matrices(particle diameter 350-800 μm) of the drug with acrylic polymer in aqueous media containing sodium carboxymethylcellulose and D-sorbitol whose pH was adjusted below 3.0. The drug release behavior of suspension precisely followed to that of original spherical matrix, suggesting little leakage of the drug from the suspended matrices during storage, The bioavailability of rapid drug release suspensions administrated orally was determined by the initial drug release rate of the suspended matrices in vitro dissolution test. Whereas the bioavailability of sustained drug release suspension orally administrated depended on the particle sires of suspended matrices, even with same drug release behavior in vitro. Finally, twice a day regimen was successfully achieved by administering orally 225.0 mg of the sustained release matrices suspended to beagle dogs.

Endogenous Inhibition of Red Blood Cell Na, K-ATPase in Essential and Pregnancy-Induced Hypertension

Digoxin-like inhibitors of Na,K-ATPase have been implicated in the pathophysiology of essential (EH) and pregnancy-induced hypertension (PIH). A technique that enhances dissociation of digoxin from red blood cells (RBC) was used to displace endogenous digoxin-like substances from RBCs. RBC membranes were preincubated in Na and ATP (Release) or Na,K,Mg and ATP (Retention) prior to measuring ATPase activity. Groups studied were: 39 men with EH and 34 controls plus 10 women with PIH and 17 normotensive controls. All displayed similar increases in Na,K-ATPase activity (24.0 +/- 7.9%) following Release. Plasma digoxin immunoreactivity (DI) was measured in pregnant women, m = 0.25 +/- 0.07 ng/ml. No DI was detected in nonpregnant women, but RBCs from these women demonstrated the same increase in Na,K-ATPase activity after Release. The 24% increase in activity achieved by Na and ATP preincubation can be reversed by adding K and Mg to the Release suspension. However, after RBC-bound digoxin is displaced by Release preincubation, addition of K and Mg cannot promote renewed binding and pump inhibition. Thus, the observed endogenous inhibition is not due to displacement of a digoxin-like substance but probably is related to alteration of the enzyme-membrane interaction. Furthermore, even though pregnant women demonstrate DI, an inhibitory substance with digoxin-like binding could not be recognized using this technique.

Sulfaethylthiadiazole V : Design and Study of an Oral Sustained Release Dosage Form

An aueous sustained release suspension of sulfaethidole (sulfaethylthiadiazole or SETD) was prepared. The velocity constant ( K b ) for drug disappearance from blood in adult human subjects was utilized to approximate the quantity of drug to be administered every twelve hours in order to maintain free SETD blood concentrations near 10 mg. per cent. Dissolution characteristics of this sustained release suspension were also studied in vitro in three different test fluids. Possible relationships with the foregoing in vivo results are discussed.