Drugs with low water solubility are predisposed to low and variable oral bioavailability and, therefore, to variability in clinical response. Despite significant efforts to "design in" acceptable developability properties (including aqueous solubility) during lead optimization, approximately 40% of currently marketed compounds and most current drug development candidates remain poorly water-soluble. The fact that so many drug candidates of this type are advanced into development and clinical assessment is testament to an increasingly sophisticated understanding of the approaches that can be taken to promote apparent solubility in the gastrointestinal tract and to support drug exposure after oral administration. Here we provide a detailed commentary on the major challenges to the progression of a poorly water-soluble lead or development candidate and review the approaches and strategies that can be taken to facilitate compound progression. In particular, we address the fundamental principles that underpin the use of strategies, including pH adjustment and salt-form selection, polymorphs, cocrystals, cosolvents, surfactants, cyclodextrins, particle size reduction, amorphous solid dispersions, and lipid-based formulations. In each case, the theoretical basis for utility is described along with a detailed review of recent advances in the field. The article provides an integrated and contemporary discussion of current approaches to solubility and dissolution enhancement but has been deliberately structured as a series of stand-alone sections to allow also directed access to a specific technology (e.g., solid dispersions, lipid-based formulations, or salt forms) where required.

Strategies to Address Low Drug Solubility in Discovery and Development

Methods are provided for inhibiting stenosis following vascular trauma or disease in a mammalian host, comprising administering to the host a therapeutically effective dosage of a therapeutic conjugate containing a vascular smooth muscle binding protein that associates in a specific manner with a cell surface of the vascular smooth muscle cell, coupled to a therapeutic agent dosage form that inhibits a cellular activity of the muscle cell. Methods are also provided for the direct and/or targeted delivery of therapeutic agents to vascular smooth muscle cells that cause a dilation and fixation of the vascular lumen by inhibiting smooth muscle cell contraction, thereby constituting a biological stent.

Therapeutic inhibitor of vascular smooth muscle cells

Drugs, especially low aqueous solubility drugs, are provided in a porous matrix form, preferably microparticles, which enhances dissolution of the drug in aqueous media. The drug matrices preferably are made using a process that includes (i) dissolving a drug, preferably a drug having low aqueous solubility, in a volatile solvent to form a drug solution, (ii) combining at least one pore forming agent with the drug solution to form an emulsion, suspension, or second solution and hydrophilic or hydrophobic excipients that stabilize the drug and inhibit crystallization, and (iii) removing the volatile solvent and pore forming agent from the emulsion, suspension, or second solution to yield the porous matrix of drug. Hydrophobic or hydrophilic excipients may be selected to stabilize the drug in crystalline form by inhibiting crystal growth or to stabilize the drug in amorphous form by preventing crystallization. The pore forming agent can be either a volatile liquid that is immiscible with the drug solvent or a volatile solid compound, preferably a volatile salt. In a preferred embodiment, spray drying is used to remove the solvents and the pore forming agent. The resulting porous matrix has a faster rate of dissolution following administration to a patient, as compared to non-porous matrix forms of the drug. In a preferred embodiment, microparticles of the porous drug matrix are reconstituted with an aqueous medium and administered parenterally, or processed using standard techniques into tablets or capsules for oral administration.

Porous drug matrices and methods of manufacture thereof

Nanosizing for oral and parenteral drug delivery: a perspective on formulating poorly-water soluble compounds using wet media milling technology.

Nanotechnology in drug delivery has been manifested into nanoparticles that can have unique properties both in vitro and in vivo, especially in targeted drug delivery to tumors. Numerous nanoparticle formulations have been designed and tested to great effect in small animal models, but the translation of the small animal results to clinical success has been limited. Successful translation requires revisiting the meaning of nanotechnology in drug delivery, understanding the limitations of nanoparticles, identifying the misconceptions pervasive in the field, and facing inconvenient truths. Nanoparticle approaches can have real impact in improving drug delivery by focusing on the problems at hand, such as enhancing their drug loading capacity, affinity to target cells, and spatiotemporal control of drug release.

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Facing the Truth about Nanotechnology in Drug Delivery

Dispersible particles consisting essentially of a crystalline anticancer agent having a surface modifier adsorbed on the surface thereof in an amount sufficient to maintain an effective average particle size of less than about 1000 nm. Anticancer compositions comprising the particles exhibit reduced toxicity and/or enhanced efficacy, and can be administered by IV bolus injection.

Surface modified anticancer nanoparticles

This invention provides a composition comprised of nanoparticles containing a therapeutic or diagnostic agent having a block copolymer linked to at least one anionic group as a surface modifier adsorbed on the surface thereof and a method of making such nanoparticles. The compositions exhibit unexpectedly improved autoclave stability, reduced macrophage uptake, improved toxicological profiles and facilitate particle size reduction such that milling time can be reduced and/or sterile filtration of the nanoparticles can be accomplished.

Sulfated nonionic block copolymer surfactants as stabilizer coatings for nanoparticle compositions

Nanoparticulate compositions comprising an insoluble organic drug and at least one polyethylene glycol-derivatized lipid adsorbed on the surface of the drug are described. The polyethylene glycol-derivatized lipid can be a PEG-phospholipid, PEG-cholesterol, PEG-cholesterol derivative, PEG-vitamin A, PEG-vitamin E, or a mixture thereof. The compositions have an effective average particle size of less than about 1 micron. The invention also describes methods of making and using such compositions.

Use of peg-derivatized lipids as surface stabilizers for nanoparticulate compositions

Disclosed are methods of intravenous administration of nanoparticulate drug formulations to a mammal to avoid adverse hemodynamic effects: by reducing the rate and concentration of the nanoparticles in the formulations; or by pretreating the subject with histamine; or by pretreating the subject with a desensitizing amount of the nanoparticulate drug formulations.

Reduction of intravenously administered nanoparticulate-formulation-induced adverse physiological reactions

Described are nanoparticulate docetaxel or analogue thereof compositions. The compositions, which comprise a nanoparticulate docetaxel or analogue thereof and at least one surface stabilizer, can be used in the treatment of cancer.

Elaine Liversidge

Papers

Surface modified anticancer nanoparticles

Sulfated nonionic block copolymer surfactants as stabilizer coatings for nanoparticle compositions

Use of peg-derivatized lipids as surface stabilizers for nanoparticulate compositions

Reduction of intravenously administered nanoparticulate-formulation-induced adverse physiological reactions

Nanoparticulate formulations of docetaxel and analogues thereof