A review on polymer–layered silicate nanocomposites

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Degradable Controlled-Release Polymers and Polymeric Nanoparticles: Mechanisms of Controlling Drug Release

Prodrugs are bioreversible derivatives of drug molecules that undergo an enzymatic and/or chemical transformation in vivo to release the active parent drug, which can then exert the desired pharmacological effect. In both drug discovery and development, prodrugs have become an established tool for improving physicochemical, biopharmaceutical or pharmacokinetic properties of pharmacologically active agents. About 5-7% of drugs approved worldwide can be classified as prodrugs, and the implementation of a prodrug approach in the early stages of drug discovery is a growing trend. To illustrate the applicability of the prodrug strategy, this article describes the most common functional groups that are amenable to prodrug design, and highlights examples of prodrugs that are either launched or are undergoing human trials.

Prodrugs: design and clinical applications

Glycoproteins, glycolipids, and glycophospholipids (glycoconjugates) are components of membranes. The oligosaccharide residue is responsible for intercellular recognition and interaction; it acts as a receptor for proteins, hormones, and viruses and governs immune reactions. These significant activities have stimulated interest in oligosaccharides and glycoconjugates. With their help it should be possible to clarify the molecular basis of these phenomena and to derive new principles of physiological activity. Major advances in the synthesis of oligosaccharides have been made by the use of the Koenigs-Knorr method, in which glycosyl halides in the presence of heavy-metal salts are employed to transfer the glycosyl group to nucleophiles. The disadvantages of this procedure have led to an intensive search for new methods. Such methods will be discussed in this article. Emphasis is placed on glycoside and saccharide formation by 1-O-alkylation, on the trichloroacetimidate method, and on activation through the formation of glycosylsulfonium salts and glycosyl fluorides.

New Methods for the Synthesis of Glycosides and Oligosaccharides—Are There Alternatives to the Koenigs‐Knorr Method? [New Synthetic Methods (56)]

Solubility, the phenomenon of dissolution of solute in solvent to give a homogenous system, is one of the important parameters to achieve desired concentration of drug in systemic circulation for desired (anticipated) pharmacological response. Low aqueous solubility is the major problem encountered with formulation development of new chemical entities as well as for the generic development. More than 40% NCEs (new chemical entities) developed in pharmaceutical industry are practically insoluble in water. Solubility is a major challenge for formulation scientist. Any drug to be absorbed must be present in the form of solution at the site of absorption. Various techniques are used for the enhancement of the solubility of poorly soluble drugs which include physical and chemical modifications of drug and other methods like particle size reduction, crystal engineering, salt formation, solid dispersion, use of surfactant, complexation, and so forth. Selection of solubility improving method depends on drug property, site of absorption, and required dosage form characteristics.

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Drug Solubility: Importance and Enhancement Techniques

Intranasal drug delivery.

Solubility enhancement of some water-insoluble drugs in the presence of nicotinamide and related compounds

A novel method of administering narcotic antagonists, narcotic analgesics and related compounds, and dosage forms containing those compounds which are adapted for nasal administration. The nasal dosage forms disclosed include solutions, suspensions, gels and ointments. The compound administered can be morphine or an analogue thereof bearing at least one phenolic hydroxyl substituent and having narcotic analgesic, antagonist or agonist-antagonist activity, or DELTA -tetrahydrocannabinol or a pharmacologically active analogue thereof bearing at least one phenolic hydroxyl substituent. Especially preferred compounds which can be advantageously administered in accordance with the invention include naloxone, naltrexone, nalbuphine, levorphanol, buprenorphine, butorphanol, DELTA -tetrahydroxannabinol (THC), cannabidiol (CBD) and levonantradol. The novel dosage forms of the invention include nasal ointments, nasal gels and isotonic nasal compositions containing the selected compound in the form of the free base, or in the case of morphine and its analogues, optionally in the form of a nontoxic pharmaceutically acceptable acid addition salt; and sustained release nasal dosage forms containing a long chain carboxylic acid salt of morphine or an analogue thereof.

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Anwar A. Hussain

Papers

Intranasal drug delivery.

Solubility enhancement of some water-insoluble drugs in the presence of nicotinamide and related compounds

Novel method of administering narcotic antagonists and analgesics and novel dosage forms containing same

Nasal absorption of propranolol from different dosage forms by rats and dogs.

Nasal absorption of propranolol in humans