Nanotechnology based drug delivery systems for the treatment of anterior segment eye diseases

Diseases affecting the anterior segment of the eye are the primary causes of vision impairment and blindness globally. Drug administration through the topical ocular route is widely accepted because of its user/patient friendliness - ease of administration and convenience. However, it remains a significant challenge to efficiently deliver drugs to the eye through this route because of various structural and physiological constraints that restrict the distribution of therapeutic molecules into the ocular tissues. The bioavailability of topically applied ocular medications such as eye drops is typically less than 5%. Developing novel delivery systems to increase the retention time on the ocular surfaces and permeation through the cornea is one of the approaches adopted to boost the bioavailability of topically administered medications. Drug delivery systems based on nanotechnology such as micelles, nanosuspensions, nanoparticles, nanoemulsions, liposomes, dendrimers, niosomes, cubosomes and nanowafers have been investigated as effective alternatives to conventional ocular delivery systems in treating diseases of the anterior segment of the eye. This review discussed different nanotechnology-based delivery systems that are currently investigated for treating and managing diseases affecting the anterior ocular tissues. We also looked at the challenges in translating these systems into clinical use and the prospects of nanocarriers as a vehicle for the delivery of phytoactive compounds to the anterior segment of the eye

Improved antimalarial activity of caprol-based nanostructured lipid carriers encapsulating artemether-lumefantrine for oral administration

Background: Artemether and lumefantrine display low aqueous solubility leading to poor release profile; hence the need for the use of lipid-based systems to improve their oral bioavailability so as to improve their therapeutic efficacy. Aim and objective: The objective of this work was to utilize potentials of nanostructured lipid carriers (NLCs) for improvement of the oral bioavailability of artemether and lumefantrine combination and to evaluate its efficacy in the treatment of malaria. This study reports a method of formulation, characterization and evaluation of the therapeutic efficacies of caprol-based NLC delivery systems with artemether and lumefantrine. Method: The artemether-lumefantrine co-loaded NLCs were prepared using the lipid matrix (5% w/w) (containing beeswax and Phospholipon\uae 90H and Caprol-PGE 860), artemether (0.1%w/w) and lumefantrine (0.6%w/w), sorbitol (4%w/w), Tween\uae 80( 2%w/w as surfactant) and distilled water (q.s to 100%) by high shear homogenization and evaluated for physicochemical performance. The in vivo antimalarial activities of the NLC were tested in chloroquine-sensitive strains of Plasmodium berghei (NK-65) using Peter\ub4s 4-day suppressive protocol in mice and compared with controls. Histopathological studies were also carried out on major organs implicated in malaria. Results: The NLC showed fairly polydispersed nano-sized formulation (z-average:188.6 nm; polydispersity index, PDI=0.462) with no major interaction occurring between the components while the in vivo study showed a gradual but sustained drug release from the NLC compared with that seen with chloroquine sulphate and Coartem\uae. Results of histopathological investigations also revealed more organ damage with the untreated groups than groups treated with the formulations. Conclusion: This study has shown the potential of caprol-based NLCs for significant improvement in oral bioavailability and hence antimalarial activity of poorly soluble artemether and lumefantrine. Importantly, this would improve patient compliance due to decrease in dosing frequency as a sustained release formulation

Effect of molecular interaction on the antiplasmodial efficacy of lumefantrine in amorphous polymethacrylate-urea solid solution

Malaria, a leading cause of mortality and morbidity in the developing world, with children aged under 5 years, accounts for 61% of all the global malaria deaths. The World Health Organization approved fixed-dose first-line artemisinin-based combination therapy (ACT) – artemether-lumefantrine for effective malaria treatment, is challenged by poor aqueous solubility and inadequate bioavailability leading to treatment failures and emergence of resistant strains. This study focuses on evaluating novel lumefantrine (LF) polymethacrylate-urea solid solutions comprising of a retarding polymer for enhanced anti-plasmodial efficacy comparable with existing artemether-lumefantrine combination therapy. Lumefantrine polymethacrylate-urea solid solutions were prepared by solvent evaporation and characterized by differential scanning calorimetry (DSC), and dissolution studies. In vivo anti-plasmodial activity was determined by measuring the schizonticidal activity of Plasmodium berghei-infected mice using the Peter’s 4-day curative test and the safety of the solid solutions was tested in major organs implicated in malaria. The solid state characterizations confirmed the formation of amorphous lumefantrine polymethacrylate-urea solid solutions. There was greater drug release from the matrix polymer in acidic than basic biorelevant media, with release kinetics following the Higuchi order. Interestingly, the reduction in parasitaemia caused by the lumefantrine polymethacrylate-urea formulations (72.3 and 81.27 %) for ternary and quaternary systems, batches SDA3 and SDB3, respectively) were significantly higher (p < 0.05) and more sustained than lumefantrine pure powder, but with comparable efficacy to the commercial brand-Coartem®. The formulation was stable over a period of 6 months. Thus, this study provides useful information on developing sustained lumefantrine formulation with improved solubility and antiplasmodial efficacy. Keywords: Solid dispersion, lumefantrine, solubility, parasitaemia reduction, eudragit polymer, Urea

Quinine: Redesigned and Rerouted

Quinine hydrochloride (QHCl) has remained a very relevant antimalarial drug 400 years after its effectiveness was discovered. Unlike other antimalarials, the development of resistance to quinine has been slow. Hence, this drug is to date still used for the treatment of severe and cerebral malaria, for malaria treatment in all trimesters of pregnancy, and in combination with doxycycline against multidrug-resistant malaria parasites. The decline in its administration over the years is mainly associated with poor tolerability due to its gastrointestinal (GIT) side effects such as cinchonism, complex dosing regimen and bitter taste, all of which result in poor compliance. Hence, our research was aimed at redesigning quinine using nanotechnology and investigating an alternative route for its administration for the treatment of malaria. QHCl nanosuspension (QHCl-NS) for intranasal administration was prepared using lipid matrices made up of solidified reverse micellar solutions (SRMS) comprising Phospholipon® 90H and lipids (Softisan® 154 or Compritol®) in a 1:2 ratio, while Poloxamer® 188 (P188) and Tween® 80 (T80) were used as a stabilizer and a surfactant, respectively. The QHCl-NS formulated were in the nanosize range (68.60 ± 0.86 to 300.80 ± 10.11 nm), and highly stable during storage, though zeta potential was low (≤6.95 ± 0.416). QHCl-NS achieved above 80% in vitro drug release in 6 h. Ex vivo permeation studies revealed that formulating QHCl as NS resulted in a 5-fold and 56-fold increase in the flux and permeation coefficient, respectively, thereby enhancing permeation through pig nasal mucosa better than plain drug solutions. This implies that the rate of absorption as well as ease of drug permeation through porcine nasal mucosa was impressively enhanced by formulating QHCl as NS. Most importantly, reduction in parasitaemia in mice infected with Plasmodium berghei ANKA by QHCl-NS administered through the intranasal route (51.16%) was comparable to oral administration (52.12%). Therefore, redesigning QHCl as NS for intranasal administration has great potential to serve as a more tolerable option for the treatment of malaria in endemic areas