Drug delivery osmotically-controlled release

SM Herbig, JR Cardinal, RW Korsmeyer, KL Smith. Asymmetric-membrane tablet coatings for osmotic drug delivery. J Controlled Release 35 127-136, 1995. 

Zentner, G. M., McClelland, G. A., and Sutton, S. C. Controlled porosity solubility- and resin-modulated osmotic drug delivery systems for release of diltiazem hydrochloride. J. Contr. Rel. 16(l-2) 237-243, 1991. 

Controlled Release Osmotic Drug Delivery Systems for Oral Applications... 

G Santus, RW Baker. Osmotic drug delivery A review of the patent literature. J Controlled Release 35 1-21, 1995. 

AG Thombre, JR Cardinal, AR DeNoto, DC Gibbes. Asymmetric membrane capsules for osmotic drug delivery. II. In vitro and in vivo performance. J Controlled Release 57 65-73, 1999. 

It is worthwhile to mention that (SB P-CD also makes controlled drug delivery more feasible for water-insoluble compound. It is well known that the release from controlled porosity osmotic pump tablets is limited due to its low aqueous solubility. However, Okimoto et al. (1999) successfully developed osmotic pump tablets for testosterone by using StjSBJD. Because each (SBEVm-P-CD molecule has an average of seven negative charges and seven sodium ions, it can act as... 

FIGURE 22.7 Azero-order release pro le with release duration of 24 h and independent of the pH ofthe dissolution medium. (Adapted from V fong, P., etal.,Modified-Release Drug Delivery Technolpt J. Rathbone, et al. (Ed ), Osmotically Controlled Tablets, Marcel Dekker, Inc., p. 107.)... 

Wong, P, et al., Osmotically controlled tablets.Nfadified-Release Drug Delivery Technology, M.J. Rathbone, etal. (Eds.), Marcel Dekker, Inc. New York, 2003, p. 107. 

The rectal milieu is quite constant as its pH is about 7.5, and the temperature is usually 37°C. It is normally empty and the pressure varies between 0 and 50 cm. This makes this route suitable for the (controlled) delivery of drugs by applying adequate (controlled release) dosage forms such as osmotic pumps and hydrogels, since the classical suppositories are, in general, not the most suitable dosage form to achieve a reproducible rate and extent of drug absorption. 

Osmotic pressure, a colligative property, depends on the concentration of solute (neutral molecule or ionic species) that contributes to the osmotic pressure. Solutions of different concentrations having the same solute and solvent system exhibit an osmotic pressure proportional to their concentrations. Thus a constant osmotic pressure, and thereby a constant influx of water, can be achieved by an osmotic delivery system that results in a constant release rate of drug. Therefore, zero-order release, which is important for a controlled release delivery system when indicated, is possible to achieve using these platforms. In 1974,... 

The principal application of these small osmotic pumps has been as implantable controlled release delivery systems in experimental studies on the effect of continuous administration of drugs. The devices are made with volumes of 0.2-2 mL. Figure 12.18 shows one such device being implanted in a laboratory rat. The delivery pattern obtained with the device is constant and independent of the site of implantation, as shown by the data in Figure 12.19. 

G. Santus and R.W. Baker, Osmotic Drug Delivery A Review of the Patent Literature, J. Controlled Release 35, 1 (1995). 

Osmotic-controlled drug release is described in detail in Chapter 4 (Section 4.6.1). Figure 6.12 illustrates the configuration of the Osmet pump for oral delivery, which resembles a rigid capsule in outer appearance and consists of ... 

Comparative pharmacokinetic profiles of nifedipine delivered from Procardia XL, an osmotic pressure-controlled drug delivery system, once-a-day versus that from Procardia, an immediate-release dosage form, taken on time 0, 8 and 16 in human volunteers. Modified from Y.W. Chien. Oral drug delivery and delivery systems. Y.W.Chien (ed.) (1992) Novel Drug Delivery Systems. Marcel Dekker, Inc. New York, pp. 139-196... 

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