Influence of Drug Properties and Routes of Drug Administration on the Design of Sustained and Controlled Release Systems

Li, Vincent

doi:10.1201/b14193-3

Cited by 41 publications

(46 citation statements)

References 294 publications

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“…An example of such a drug is theophylline, which has a narrow therapeutic window and a relatively short half-life in children (Kadlec, Ha et al 1978). Furthermore, poor patient compliance is more likely to happen in the case of regimens requiring frequent administration, and is often an important reason for therapeutic inefficiency or failure (Li, Robinson et al 1987;Collett and Moreton 2002). …”

Section: Immediate Drug-release Dosage Formsmentioning

confidence: 99%

“…CR, on the other hand, indicates that the delivery system is able to provide some actual therapeutic control, whether this be of a temporal nature, spatial nature, or both; that is, it attempts to control drug concentrations in the target tissue or cells. These definitions suggest that SR systems, which only prolong therapeutic blood or tissue concentrations of the drug for an extended period of time, cannot be considered as CR systems (Li, Robinson et al 1987;Jantzen and Robinson 2002). However, there has been considerable confusion regarding the terminology of these dosage forms (Li, Robinson et al 1987;Buri and Doelker 1997;Jantzen and Robinson 2002).…”

Section: Modified Drug-release Dosage Formsmentioning

confidence: 99%

“…These definitions suggest that SR systems, which only prolong therapeutic blood or tissue concentrations of the drug for an extended period of time, cannot be considered as CR systems (Li, Robinson et al 1987;Jantzen and Robinson 2002). However, there has been considerable confusion regarding the terminology of these dosage forms (Li, Robinson et al 1987;Buri and Doelker 1997;Jantzen and Robinson 2002).…”

Section: Modified Drug-release Dosage Formsmentioning

confidence: 99%

“…Thus, CR may be considered to include a broad number of objectives such as, among others, 1) to increase drug solubility and dissolution rates in order to improve absorption and, as a result, bioavailability; 2) to prolong retention in the stomach in order to control not only the rate of release but also the site of release; 3) to protect drugs and bioactive agents, such as peptides, proteins and enzymes, from degradation within the gastrointestinal tract; 4) to protect the stomach from the irritating effects of some drug by means of, for example, enteric coatings; and 5) to deliver drugs to their absorption window or to specific targets within the gastrointestinal tract, often the colon (site-specific) (Li, Robinson et al 1987;.…”

Section: Modified Drug-release Dosage Formsmentioning

confidence: 99%

“…The main goals of oral SR products, on the other hand, can be described as follows (Li, Robinson et al 1987;Gupta and Robinson 1992;Collett and Moreton 2002;Das and Das 2003;Rajabi-Siahboomi 2003;Kumar, Bhowmik et al 2010):…”

Section: Modified Drug-release Dosage Formsmentioning

confidence: 99%

See 4 more Smart Citations

High-amylose carboxymethyl starch matrices for oral sustained drug-release: In vitro and in vivo evaluation

Nabais

Brouillet

Kyriacos

et al. 2007

European Journal of Pharmaceutics and Biopharmaceutics

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Section: Immediate Drug-release Dosage Formsmentioning

confidence: 99%

Section: Modified Drug-release Dosage Formsmentioning

confidence: 99%

Section: Modified Drug-release Dosage Formsmentioning

confidence: 99%

Section: Modified Drug-release Dosage Formsmentioning

confidence: 99%

Section: Modified Drug-release Dosage Formsmentioning

confidence: 99%

See 3 more Smart Citations

High-amylose carboxymethyl starch matrices for oral sustained drug-release: In vitro and in vivo evaluation

Nabais

Brouillet

Kyriacos

et al. 2007

European Journal of Pharmaceutics and Biopharmaceutics

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Controlled Release Technology, Pharmaceutical

Edgren

Leeper

Nichols

et al. 2000

Kirk-Othmer Encyclopedia of Chemical Technology

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Controlled-release dosage forms enhance the safety, efficacy, and reliability of drug therapy. They regulate the drug release rate to control drug action and reduce the frequency of drug administration to encourage patients to comply with dosing instructions. Conventional dosage forms often lead to wide swings in serumdrug concentrations. Most of the drug content is released soon after administration, causing drug levels in the body to rise rapidly, peak, and then decline sharply. For drugs whose actions correlate with their serumdrug concentration, these sharp fluctuations often cause unacceptable side effects at the peaks, followed by inadequate therapy at the troughs (Fig. 1). Administering smaller doses at more frequent intervals can damp concentration fluctuations, preventing over-and underdosing, but the inconvenience may cause patients to skip or delay doses, degrading efficacy. Compliance, measured as the percentage of patients taking 95% to 105% of prescribed oral medications, decreased from 67% with once-a-day regimens to 22% with four-times-a-day regimens (1). These difficulties are especially pronounced with drugs that have short half-lives and a narrow range of safe and effective concentrations. Precisely controlled release is particularly valuable for such agents (see Drug delivery systems).The term controlled release technology generally refers to a variety of methods used to exert various degrees of control over drug release. The U.S. Food and Drug Administration (FDA) defines controlled release dosage forms as those formulations designed to release active ingredient(s) at rates that differ significantly from their corresponding immediate release forms (2). The indexing system of Index Medicus supports this broad definition by classifying these dosage forms as delayed-action preparations, and Excerpta Medica uses the index term sustained release preparations. The pharmaceutical literature contains a profusion of terms, including delayed-action, extended action, gradual release, prolonged release, protracted release, slow release, sustained release, depot, retard, and timed-release dosage forms, all emphasizing an increased duration of action (3).To avoid confusion, several researchers have incorporated therapeutic intention into the definition of controlled release (4-7). Thus, controlled-release pharmaceuticals release drugs in vivo according to a predictable, therapeutically rational, programmed rate to achieve the optimal drug concentration in the minimal time (4). Specification by release rate complements specification by quantity; jointly considered, they fix the duration of drug release. Therefore, the drug's duration of action can become a design property of a controlled release dosage form rather than an inherent pharmacokinetic property of the drug molecule.Under this more precise definition, controlled release drug delivery not only provides a predictable, patterned action, but controls the rate of drug release for a predetermined period. Controlled release systems deliver drugs at a con...

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