Nose to brain microemulsion-based drug delivery system of rivastigmine: formulation and ex-vivo characterization.

Alzheimer's disease (AD) is a progressive neurodegenerative disorder leading to irreversible loss of neurons, cognition and formation of abnormal protein aggregates. Rivastigmine, a reversible cholinesterase inhibitor used for the treatment of AD, undergoes extensive first-pass metabolism, thus limiting its absolute bioavailability to only 36% after 3-mg dose. Due to extreme aqueous solubility, rivastigmine shows poor penetration and lesser concentration in the brain thus requiring frequent oral dosing. This investigation was aimed to formulate microemulsion (ME) and mucoadhesive microemulsions (MMEs) of rivastigmine for nose to brain delivery and to compare percentage drug diffused for both systems using in-vitro and ex-vivo study. Rivastigmine-loaded ME and MMEs were prepared by titration method and characterized for drug content, globule size distribution, zeta potential, pH, viscosity and nasal ciliotoxicity study. Rivastigmine-loaded ME system containing 8% w/w Capmul MCM EP, 44% w/w Labrasol:Transcutol-P (1:1) and 48% w/w distilled water was formulated, whereas 0.3% w/w chitosan (CH) and cetyl trimethyl ammonium bromide (as mucoadhesive agents) were used to formulate MMEs, respectively. ME and MMEs formulations were transparent with drug content, globule size and zeta potential in the range of 98.59% to 99.43%, 53.8 nm to 55.4 nm and -2.73 mV to 6.52 mV, respectively. MME containing 0.3% w/w CH followed Higuchi model (r(2) = 0.9773) and showed highest diffusion coefficient. It was free from nasal ciliotoxicity and stable for three months. However, the potential of developed CH-based MME for nose to brain delivery of rivastigmine can only be established after in-vivo and biodistribution study.

Docking study of novel antihyperlipidemic thieno[2,3-d]pyrimidine; LM-1554, with some molecular targets related to hyperlipidemia - an investigation into its mechanism of action.

An investigation into the mechanism of antihyperlipidemic action of 2-chloromethyl-5,6,7,8-tetrahydrobenzo(b)thieno[2,3-d]pyrimidin-4(3H)-one (LM-1554) was carried out through docking experiments with six different molecular targets; Niemann Pick C1 Like1 protein (NPC1L1), ATP citrate lyase (ACL), C-reactive protein (CRP), lanosterol 14α-demethylase (LDM), squalene synthase (SqS) and farnesiod X-receptor (FXR) known to be implicated in the physiology of hyperlipidemia. The interactions of LM-1554 were compared with the interactions of their respective co-crystallized native ligands at the active sites of these receptors. These comparisons are based on their docking parameters, as well as, types of interactions and vicinity with various amino acids in the active site pockets. The interaction of LM-1554 with the target, NPC1L1 has been found to be the quite favourable as compared to those with the other targets assessed in this study.

Some molecular targets for antihyperlipidemic drug research.

High levels of cholesterol and other lipid constituents are major risk factors in the development of atherosclerosis as well as diseases and disorders associated with it. Though, drugs of various categories acting through different mechanisms are available for antihyperlipidemic therapy, there are limitations associated with each of them, keeping the interest in discovery of newer and better antihyperlipidemic drugs alive. Identification and exploitation of novel molecular targets for discovery of new antihyperlipidemic drugs is an important area of research. Twenty such drug targets are elaborated herein, for their biochemical roles, structures, estimations, as well as, exploitation for new drug discovery research. Few recently discovered drugs are based on such molecular targets are also discussed.

The chemistry and biological potential of azetidin-2-ones.

Azetidin-2-ones, commonly referred as ß-lactams, represent a unique ring system, with interesting chemistry and great biological potential. Besides its well known antibiotic activity, this ring system exhibits a wide range of activities, attracting the attention of researchers. The biological and pharmacological profile of azetidin-2-ones is reviewed here comprehensively with several examples under fourteen different activity heads. The chemistry and methods of synthesis have also been discussed.

Design, synthesis and pharmacological evaluation of a series of 5-carbethoxy-4-chloro-6-(substituted amino)pyrimidines as potential analgesic and anti-flammatory agents with very low ulcerogenic potential.

A series of 5-carbethoxy-4-chloro-6-(substituted amino)pyrimidines was designed on the basis of its good 3-dimensional structural similarity with mefenamic acid (CAS 61-68-7), a well known anti-inflammatory drug. Synthesis of some 5-carbethoxy-4-chloro-6-(substitutedamino)pyrimidines has been achieved by cyclization of N-(cyanovinyl)formamidine intermediate in the presence of dry HCl. Target compounds were evaluated for their analgesic and anti-inflammatory potential by known experimental models. Some of the compounds emerged as more potent analgesic and anti-inflammatory agents than the standard drug diclofenac sodium (CAS 15307-79-6). A very low ulcer index was observed with the most potent compound.

Synthesis and antihyperlipidemic activity of some novel condensed 2-chloroalkyl-4-chloro/hydroxy-5,6-disubstituted pyrimidines.

Synthesis and antihyperlipidemic activity of a series of novel condensed 2-chloroalkyl-4-chloro/hydroxy-5,6-di-substituted pyrimidines are described. The design of these compounds is based on the earlier QSAR study on the antihyperlipidemic 2-substituted methylthienopyrimidin-4-ones. The newly synthesized condensed 4-chloro-2-chloroalkylpyrimidines (IIIa-n) have exhibited much superior antihyperlipidemic activity, compared to their earlier reported 4-hydroxy analogs. Notably, in this series, five compounds, IIIa, IIIb, IIIc, IIIi and IIIm showed good ability to reduce total cholesterol and two compounds, IIIa and IIIk exhibited better reduction in serum triglycerides. All the newly synthesized compounds have been evaluated by the Triton WR 1339 induced hyperlipidemia in albino Wistar rats model for antihyperlipidemic activity, and their activity is superior to that exhibited by the standard gemfibrozil used in the study. A 3D QSAR study has also been performed to delineate the effect of the substituents at 5 and 6 positions on the antihyperlipidemic activity of 2-chloromethyl-5,6-substituted thieno(2,3-d) pyrimidin-4(3H)-ones (IIa-e).

The biology and chemistry of hyperlipidemia.

Coronary arterial diseases are responsible for more deaths than all other associated causes combined. Elevated serum cholesterol levels leading to atherosclerosis can cause coronary heart disease (CHD). Reduction in serum cholesterol levels reduces the risk for CHD, substantially. Medicinal chemists all around the world have been designing, synthesizing, and evaluating a variety of new bioactive molecules for lowering lipid levels. This review summarizes the disorders associated with elevation of lipids in blood and the current strategies to control them. The emphasis has been laid in particular on the new potential biological targets and the possible treatments as well as the current ongoing research status in the field of lipid lowering agents.