B. A. Aderibigbe

Kinetic release studies of nitrogen-containing bisphosphonate from gum acacia crosslinked hydrogels

Natural polymer hydrogels are useful for controlling release of drugs. In this study, hydrogels containing gum acacia were synthesized by free-radical polymerization of acrylamide with gum acacia. The effect of gum acacia in the hydrogels on the release mechanism of nitrogen-containing bisphosphonate (BP) was studied at pH 1.2 and 7.4. The hydrogels exhibited high swelling ratios at pH 7.4 and low swelling ratios at pH 1.2. The release study was performed using UV-Visible spectroscopy via complex formation with Fe(III) ions. At pH 1.2, the release profile was found to be anomalous while at pH 7.4, the release kinetic of BP was a perfect zero-order release mechanism. The hydrogels were found to be pH-sensitive and the release profiles of the BP were found to be influenced by the degree of crosslinking of the hydrogel network with gum acacia. The preliminary results suggest that these hydrogels are promising devices for controlled delivery of bisphosphonate to the gastrointestinal region.

Evaluation of whey protein isolate-graft-carbopol-polyacrylamide pH-sensitive composites for controlled release of pamidronate

Whey protein isolate-graft-carbopol-polyacrylamide pH sensitive hydrogel composites were prepared by simultaneous redox cross-linked polymerization of whey protein isolate, acrylamide and carbopol. The hydrogel composites were characterized by SEM, FTIR, XRD and swelling analysis was performed on the hydrogels. The hydrogels were pH sensitive, degradable and protected the entrapped drug in the matrix. The aforementioned factors were influenced by the grafting of whey protein isolate onto the composite networks. The release of pamidronate from the hydrogel followed a super case 2 transport suggesting that the release mechanism was a combination of erosion and diffusion at pH 7.4. At pH 1.2, the release mechanism of pamidronate from the hydrogels was a quasi-Fickian diffusion. The SEM images of the hydrogels after drug release indicated degradability of the hydrogels. The results obtained suggested that whey protein isolate is a potential biopolymer for controlled drug delivery systems with enhanced drug bioavailability.

Immiscible Polymer Blends Stabilized with Nanophase

The importance of phase morphology in immiscible blend makes the issue of stability also very important. In this chapter, we try to explain the role of nanoparticles in the stabilization of dispersed phases from the experimental and theoretical point. As inorganic particles, it might seem impossible from the classical chemistry point of view. However, their sizes and shapes have them some very important advantages, such that interactions that may not have been possible with microsize particles now are with nanoscale particles. However, it is not as straightforward as it sounds. Therefore, factors that are necessary for these particles to act as compatibilizers and those required of the polymer blends are discussed here so that first timers in material science of polymer blends can follow through.

Synthesis, characterization and the release kinetics of antiproliferative agents from polyamidoamine conjugates.

Abstract Polyamidoamine conjugates containing curcumin and bisphosphonate were synthesized via a one-pot aqueous phase Michael addition reaction. In the design of the conjugate, bisphosphonate formed an integral part of the polymer carrier backbone. Curcumin was incorporated onto the polyamidoamine backbone via piperazine linker. The conjugates were characterized by Fourier transform spectroscopy, energy-dispersive X-ray analysis, atomic force spectroscopy and nuclear magnetic resonance spectroscopy and it confirmed the successful incorporation of the antiproliferative agents onto the carriers. The weight percentage incorporation of bisphosphonate to the carriers was found to be between 2.56% and 3.34%. The in vitro release studies of curcumin from the polyamidoamine conjugate were performed in dialysis bag at selected pH values. The release of curcumin was significantly slower at pH 7.4 when compared to pH 5.8. The release profiles indicate that the conjugates are more stable at pH 7.4 and are potential sustained drug-delivery systems for combination therapy.

Design and Efficacy of Nanogels Formulations for Intranasal Administration

Nanogels are drug delivery systems that can bypass the blood-brain barrier and deliver drugs to the desired site when administered intranasally. They have been used as a drug delivery platform for the management of brain diseases such as Alzheimer disease, migraine, schizophrenia and depression. nanogels have also been developed as vaccine carriers for the protection of bacterial infections such as influenza, meningitis, pneumonia and as veterinary vaccine carriers for the protection of animals from encephalomyelitis and mouth to foot disease. It has been developed as vaccine carriers for the prevention of lifestyle disease such as obesity. Intranasal administration of therapeutics using nanogels for the management of brain diseases revealed that the drug transportation was via the olfactory nerve pathway resulting in rapid drug delivery to the brain with excellent neuroprotective effect. The application of nanogels as vaccine carriers also induced significant responses associated with protective immunity against selected bacterial and viral infections. This review provides a detailed information on the enhanced therapeutic effects, mechanisms and biological efficacy of nanogels for intranasal administration.

Polymeric Nanocarriers for the Delivery of Antimalarials

Malaria is an infectious disease caused by a protozoan parasite which is transmitted by female Anopheles mosquitoes around tropical and sub-tropical regions. Half of the world’s population is at risk of being infected by malaria. This mainly includes children, pregnant women and people living with chronic diseases. The main factor that has contributed to the spread of this disease is the increase in the number of drug-resistant parasites. To overcome drug resistance, researchers have developed drug delivery systems from biodegradable polymers for the loading of antimalarials. The drug delivery systems were characterized by distinct features such as good biocompatibility, high percentage drug encapsulation, reduced drug toxicity and targeted drug delivery. In this review article, we highlight the various types of drug delivery systems developed from polymeric nanocarriers used for the delivery of antimalarials.

Application of Dendrimers for the Treatment of Infectious Diseases

Dendrimers are drug delivery systems that are characterized by a three-dimensional, star-shaped, branched macromolecular network. They possess ideal properties such as low polydispersity index, biocompatibility and good water solubility. They are made up of the interior and the exterior layers. The exterior layer consists of functional groups that are useful for conjugation of drugs and targeting moieties. The interior layer exhibits improved drug encapsulation efficiency, reduced drug toxicity, and controlled release mechanisms. These unique properties make them useful for drug delivery. Dendrimers have attracted considerable attention as drug delivery system for the treatment of infectious diseases. The treatment of infectious diseases is hampered severely by drug resistance. Several properties of dendrimers such as their ability to overcome drug resistance, toxicity and control the release mechanism of the encapsulated drugs make them ideal systems for the treatment of infectious disease. The aim of this review is to discuss the potentials of dendrimers for the treatment of viral and parasitic infections.

17 – Biomedical applications of polyolefins

In this chapter we discuss the use of polyolefins (POs) in the biomedical fields; POs being the largest volume polymers in the plastic industry today. The main focus will be on the two main types of POs, viz: polyethylene (PE) and polypropylene (PP), which have substantial biomedical applications in addition to their other uses. Hence, an overview of PE, PP, other higher POs, and their properties are reviewed to map out the technical characteristics that are advantageous for biomedical applications. POs are easy to fabricate into useful products and have increasing design capability. They also have the potential for use in many applications because of their excellent cost/performance values such as low density, easy recyclability, and diverse processability. Biomedical applications of these POs in medical implants, medical devices, and in the production of pharmaceutical consumables in the form of packaging materials; vials, bottles, and syringes will be highlighted with numerable references made.

Gum acacia polysaccharide-based pH sensitive gels for targeted delivery of neridronate

The preparation of polysaccharide-based gels from a combination of natural and synthetic polymers results in polymer networks with unique physicochemical properties. Polysaccharide-based gels were prepared from a combination of gum acacia, a polysaccharide, and synthetic polymers using the free radical polymerization technique. The gels were characterized by XRD, DSC, SEM, and FTIR. The swelling abilities of the gels were performed at pH 1.2 and 7.4. Release kinetic studies of neridronate from the prepared gels were performed and the release mechanism was found to be super case transport II at pH 1.2 and pH 7.4. The gels were pH sensitive and the release profile of neridronate from the gels network was influenced by the degree of cross-linking of their network and pH. The preliminary results suggest that these gels are promising devices for targeted delivery of neridronate to the gastrointestinal region.

Polymer Therapeutics: Design, Application, and Pharmacokinetics

Abstract Polymer therapeutics are nanosized water-soluble polymers to which drugs are covalently bound. Drugs are incorporated onto the polymers by a technique known as polymer–drug conjugation. Some of them have been approved for the treatment of some diseases. They exhibit several advantages, such as: enhanced water solubility of the conjugated drug, nontoxic, reduced drug toxicity, enhanced drug bioavailability and prolonged plasma half-life resulting in reduced kidney clearance, protection of drug from degrading enzymes, nonimmunogenic, nonantigenic, specific accumulation in organs, tissues, or cells by enhanced permeability and retention effect, reduced drug resistance and can be used for multiple-drug delivery. This chapter focuses on the progress and up-to-date design, application, and the pharmacokinetics of polymer therapeutics.