Recent Patents on Drug Delivery & Formulation - Volume 1, Issue 3, 2007

It is challenging to develop innovative, as well as commercially viable, lipid-based drug delivery systems for the treatment of cancer because of the breadth of existing intellectual property that limits freedom-to-operate. For example, novel compositions can be described in which a new chemical entity is associated with a lipid based carrier, but if the loading method or components of the lipid compositions are proprietary then the ability to develop novel compositions will require access to the appropriate intellectual property. We believe it is useful to present a review of the patent literature describing novel liposomal drug delivery systems given by parenteral administration to humans for the treatment of serious medical conditions such as cancer. This review is intended to: (i) identify and describe novel approaches that have recently been protected by US or international patents and patent applications, and; (ii) identify founding technology in the field which is recently off-patent, thus presenting emerging opportunities for the development of new therapeutic options for patients. Issued patents, and selected patent applications, having publication dates in 2005 or 2006 were retrieved from searches of the US, European, German, Japanese, INPADOC and WIPO PCT databases. Liposomal delivery systems patented for systemic administration in the treatment of human medical conditions were reviewed in detail.

Transdermal drug delivery offers certain advantages over conventional oral or parenteral administration. However, the excellent barrier function of the skin, accomplished almost entirely by the stratum corneum, restricts the number of drug substances that can be administered transdermally to those with very specific physicochemical properties. Several approaches have been used to enhance the transport of drugs through the stratum corneum. However, in many cases, only moderate success has been achieved and each approach is associated with significant problems. Microstructured devices, consisting of a plurality of microprojections attached to a support, can be used to painlessly bypass the stratum corneum barrier and thus achieve successful transdermal delivery. Moreover, microprojection devices also enable minimally-invasive sampling and monitoring of biological fluids. Much activity is currently focussed in this area. Accordingly, this article deals with the innovations pertaining to microprojection-based devices for transdermal drug delivery and minimally-invasive monitoring as disclosed in recent patent literature.

Nowadays, pharmaceutical technology and research for new drugs and formulations is of great importance, as scientists attempt to discover even more revolutionary and efficient methods to treat various diseases. At the same time the correct dosing and site targeting are equally important for clinical success. Research in sustained drug release systems is very promising towards such a direction, while it offers advantages and potential rewards contrary to traditional therapy. The drug plasma concentrations remain inside the therapeutic range for a longer time period compared to the conventional formulations. In addition, sustained release formulations may increase the likelihood for the patient to respond to the therapy, since drug formulations are generally characterized by one daily given dose. The rate at which a drug is released from a sustained-release formulation depends upon many factors, while excipients play the most important role. Most sustained release formulations are based on biodegradable polymers in the form of a drug-encapsulating matrix or membrane. Examples range from monolithic devices, polymer-coated capsules and implant devices, hydrogels, to injectable systems based on suspensions of micro-, nanospheres or polymer solutions [1-5]. The advantages and disadvantages of these different formulation systems are being extensively discussed in the present review.

Outstanding progress has been made in drug delivery approaches. However, challenges still exist in delivering clinically optimal levels of therapeutic molecules. Advances in nanotechnology and nanomedicine have heralded the advent of several innovative nanomaterials which are set to revolutionize the field of drug delivery. Carbon nanotubes are one such novel class of nanomaterials that are gaining increasing attention. They have been modified with several molecules of therapeutic interest. Excellent progress has been made in harnessing the potential of carbon nanotubes for several drug delivery and other applications. Functionalized carbon nanotubes have been demonstrated to deliver proteins, nucleic acids, drugs, antibodies and other therapeutics. Emerging developments in this area are pointing towards the successful utilization of carbon nanotubes for drug delivery. This review presents a comprehensive summary of the recent patents in carbon nanotube mediated drug delivery systems, their clinical significance, limitations and future prospects.

Colon delivery is especially required for drugs intended to act locally or for drugs that exhibit maximum systemic absorption from the colon. However, exposure to extreme pH conditions, gastric enzymes, bile salts and variation in gastric emptying makes the development of colon release dosage forms extremely challenging. The approaches generally used for formulating a colon release dosage form include use of pH dependent release polymers, time-release coatings, prodrugs and biodegradable polymers. Although, considerable choice exists while selecting a pH dependent release polymer, the drug release from these polymers is easily influenced by nature of diet and disease. In addition, while these polymers may prevent drug release in stomach (pH 1-3) and proximal small intestine (pH 6.5), the drug may be prematurely released in vivo in lower small intestine (pH 7.5). Similarly, variation in gastric transit time due to nature of diet and severity of disease often lead to reduced performance of time-release based colon delivery dosage forms. Therefore, new approaches are continuously being evaluated to ensure compliance with requirement of colon release and to reduce the variation in their performance. This article is aimed at studying the recent patents with a view to unveil new concepts being put into use for designing colon release dosage forms.

The vaccination of wildlife reservoirs of infection is important for effective disease control programs and usually requires the use of oral vaccines. Current inventions in the field of oral baits for the immunization of wildlife cover effective vaccine compositions, vaccine containers to deliver the vaccine orally to target species, and baits that specifically attract the target species. Oral bait vaccine formulations need to provide an effective field performance, safety, cost-effectiveness, less waste, and improved environmental compliance. Herein, we review recent patents in oral bait vaccine formulations for the immunization of wildlife and particularly of terrestrial wild mammals. Recent progress in this field suggests that the application of oral bait vaccines to wildlife will impact disease control in the near future.

In recent years, novel drug delivery systems (NDDS) have been recognized as an attractive niche for the pharmaceutical and health industry. Among various NDDS, osmotic drug delivery systems (ODDS) are most interesting and widely applicable. Osmotic drug delivery system use osmotic pressure for controlled delivery of active agent(s). Drug delivery from these systems, to a large extent is independent of the physiological factors of gastrointestinal tract. ODDS have matured from their use with laboratory animals to most reliable controlled release systems for humans. Most of the knowledge about ODDS is found in patents, which are difficult to read, analyze and judge because of their peculiar style in which they are written. Santus and Baker [1] reviewed ODDS patents up to year 1993; this review article gives an overview of ODDS patents from year 1994 to 2006.

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