Nanocrystals: industrially feasible multifunctional formulation technology for poorly soluble actives

Poor solubility of new drugs and their related low oral bioavailability and general delivery problems are becoming a major challenge. Nanocrystals being a kind of "universal" formulation approach for these molecules are reviewed in this paper regarding the industrial feasibility, i.e. industrially available production processes (bottom-up and top-down technologies), regulatory aspects and nanotoxicology. This article also includes second generation nanocrystals (<<100 nm) as smartCrystals. The status of products on the market and in clinical phases is presented. The different special features of nanocrystals, which are exploited in different products, are described (tablets, capsule, aqueous nanosuspension). The main focus is given for oral and intravenous products. However, the potential and delivery strategies for other administration routes are discussed, i.e. dermal and mucosal, ocular, pulmonary and targeted delivery (e.g. via differential protein adsorption to the brain). In addition, the potential of the nanocrystal technology for delivery of poorly soluble, non-pharmaceutical actives is highlighted, i.e. in cosmetics or nutraceuticals.

Delivery of antiinflammatory nutraceuticals by nanoparticles for the prevention and treatment of cancer

Extensive research within the last two decades has revealed that most chronic illnesses, including cancer, diabetes, and cardiovascular and pulmonary diseases, are mediated through chronic inflammation. Thus, suppressing chronic inflammation has the potential to delay, prevent, and even treat various chronic diseases, including cancer. Various nutraceuticals from fruits, vegetables, vitamins, spices, legumes, and traditional Chinese and Ayurvedic medicine have been shown to safely suppress proinflammatory pathways; however, their low bioavailability in vivo limits their use in preventing and treating cancer. We describe here the potential of nanotechnology to fill this gap. Several nutraceuticals, including curcumin, green tea polyphenols, coenzyme Q, quercetin, thymoquinone and others, have been packaged as nanoparticles and proven to be useful in "nanochemoprevention" and "nano-chemotherapy".

Nanoparticulate strategies for effective delivery of poorly soluble therapeutics

The pharmacological activity of a drug molecule depends on its ability to dissolve and interact with its biological target, either through dissolution and absorption, or through dissolution and receptor interaction. The low bioavailability that characterizes poorly water-soluble drugs is usually attributed to the dissolution kinetic profile. Novel strategies to effectively deliver these drugs include nanoparticulate approaches that either increase the surface area of the drug or improve the solubility characteristics of the drug. Nanosizing approaches are based on the production of drug nanocrytals dispersed in an aqueous surfactant solution, whereas other possibilities include drug loading in nanoparticles. Promising nanoparticulate approaches include the development of lipid-based nanocarriers to increase drug solubility followed by enhanced bioavailability. To select the best approach there are, however, some critical considerations to take into account, for example the physicochemical properties of the drug, the possibility to scale-up the production process, the toxicological considerations of the use of solvents and cosolvents, the selection of an environmentally sustainable methodology and the development of a more patient-friendly dosage form. This article addresses these relevant questions and provides feasible examples of novel strategies with respect to relevant administration routes.

Nanotechnology and therapeutic delivery: a drug regulation perspective

Nanotechnology is expected to contribute to the therapeutic delivery field in the coming decade. Although the US FDA has multiple guidance documents in place to deal with novel drug products, nanoparticles may produce issues that have not been previously encountered with small drug molecules. This regulatory focus highlights some current guidance documents and thinking of the FDA as applied to nanoparticles used for therapeutic delivery.

Targeted intracellular delivery of hydrophobic agents using mesoporous hybrid silica nanoparticles as carrier systems

Targeted nanoparticle-mediated intracellular delivery is demonstrated using two hydrophobic fluorophores as model drug cargo. The presented hybrid carrier system exhibits both cancer cell-targeting ability and capacity to retain a hydrophobic agent with subsequent specific release into the endosomal compartment. Furthermore, the incorporated agent is shown to be able to escape from the endosomes into the cytoplasm, making the particles promising candidates as carriers for targeted drug delivery for cancer treatment.

Diet calcium level but not calcium supplement particle size affects bone density and mechanical properties in ovariectomized rats

Calcium (Ca) supplements, especially Ca carbonate (CaCO3), are the main alternative sources of dietary Ca and an important part of a treatment regimen for osteoporosis, the most common metabolic bone disorder of aging and menopause. In a female ovariectomized (OVX) rat model for studying postmenopausal osteoporosis, we tested the hypothesis that a small compared with a large particle size of CaCO3 (13.0- vs. 18.5-mum geometric diameter) would result in increased Ca balance and subsequently bone mass and that this would be affected by dietary Ca level. We used 6-mo-old rats that were OVX either at 6 or 3 mo of age as models of early or stable menopausal status, respectively. The rats received semipurified diets that contained either 0.4 or 0.2% dietary Ca provided from CaCO3 of 2 particle sizes. A group of Sham-operated rats with intact ovaries served as control and were fed 0.4% dietary Ca from large particles. Estrogen deficiency as a result of ovariectomy had an adverse effect on bone density, mineral content, and bone mechanical properties (P < 0.001). Reducing dietary Ca from 0.4 to 0.2% resulted in significant adverse effects on bone density and mechanical properties (P < 0.001). The particle size of CaCO3 did not affect total Ca balance, bone dual energy X-ray absorptiometry and peripheral quantitative computed tomography indices, bone ash and Ca content, or the mechanical determinants of bone strength. We conclude that a decrease in particle size of CaCO3 to 70% of that typically found in Ca supplements does not provide a benefit to overall Ca metabolism or bone characteristics and that the amount of Ca consumed is of greater influence in enhancing Ca nutrition and skeletal strength.