Notes On Nano Suspension & Project Report - Pharmacy Project Report

INTRODUCTION
The oral route is the preferred route for chronic drug therapy. Numerous potent lipophilic drugs exhibit low oral bio availability due to their poor aqueous solubility properties. For this class of compounds, defined by Amidon et al. as `low solubility/high permeability classП, dissolution in the environmental lumen is the rate controlling step in the absorption process1. Efforts are ongoing to enhance the oral bio availability of lipophilic drugs in order to increase their clinical efficacy. The most popular approach is the incorporation of the active lipophilic component into inert lipid vehicles2, such asoils3, surfactant dispersions4,5, self-emulsifying formulations6.,7, emulsions 8,9 and liposomes10, with every formulation approach having its special advantages and limitations. Efficacy of lipophilic drug is often hindered due to their poor aqueous solubility leading to low absorption after invivo administration. A part of the administered dose is absorbed and reaches the pharmacological site of actionand remainder causes toxicity and undesirable side effectsdue to unwanted biodistribution. Enhancement in drugefficacy and lowering of drug toxicity could be achieved through encapsulation and delivery the drug in lipid based delivery system.The concept of drug delivery system has emerged to minimize the toxic side effects of drug, to broaden their application, to expand modes of their administration and to solve absorption problems.11-20Self-emulsifying drug delivery systems (SEDDS) are mixtures of oils and surfactants, ideally isotropic,and sometimes containing co-solvents, which emulsify spontaneously to produce fine oil-in-water emulsions when introduced into aqueous phase under gentleagitation6, 7,39,40,41. Recently, SEDDS have been formulate dusing medium chain tri-glyceride oils and non ionic
surfactants, the latter being less toxic. Upon per oral administration, these systems form fine emulsions (ormicro-emulsions) in gastro-intestinal tract (GIT) with mild agitation provided by gastric mobility.42, 43 Potential advantages of these systems include enhanced oral bio availability enabling reduction in dose, more consistent temporal profiles of drug absorption, selective targeting of drug(s) toward specific absorption window in GIT, and protection of drug(s) from the hostile environment ingut.44, 45The oral route is the favourite route for chronic drug therapy, majority of drugs are frequently administered through oral route, but approximately 40% of new drug candidates have poor‐water solubility and the oral delivery of such drugs is complicated for thereason that of their low bio availability, high intra‐ and inter‐subject variability, and not have dose linearity. To overcome these problems, a variety of strategies have been developed including the use of surfactants,lipids, permeation enhancers, micronization,salt formation, cyclodextrins, nano particlesand solid dispersions, and self emulsifying drug delivery system, etc1.Recently, due to better and consistent results,there is a enormous prominence on self‐emulsifying drug delivery systems(SEDDS) to improve the oral bio availability of lipophilic drugs. There has been emergent attention in the use of lipid excipients in self‐emulsifying lipid formulations (SELFs) for the reason that of their capability to solubilise poorly water‐soluble 'lipophilic' drugs and prevail over the problem of poor drug absorption and bio availability
 

 SELF EMULSIFYING AND SELF MICRO EMULSIFYING DRUG DELIVERY SYSTEM:-

The drugs are most often administered by oral route, but approximately 40% of new drug candidates have poor‐water solubility and the oral delivery of such drugs is difficult because of their low bio availability, high intra‐ and inter‐subject variability, and a lack of dose proportionality. To overcome these problems, various strategies are exploited including the use of surfactants, lipids,permeation enhancers, micronization, salt formation, cyclodextrins,nano particles and solid dispersions 1,2.There are a number of formulation strategies that could be used to improve the bio availability of class II drugs, either by increasing the dissolution rate or by presenting the drug in solution and maintaining the drug In solution in the intestinal lumpen.


Advantages of self-emulsifying drug delivery systems conventional drug
delivery systems
Potential advantages of these systems (SEDDS) include
1. Enhanced oral bioavailability enabling reduction in dose.
2. More consistent temporal profiles of drug absorption.
3. Selective targeting of drug(s) toward specific absorptionwindow in GIT
4. Protection of drug(s) from the hostile environment in gut.
5. Control of delivery profiles.
6. Reduced variability including food effects.
7. Protection of sensitive drug substances.
8. High drug payloads.
9. Liquid or solid dosage forms
 
TYPES OF  SELF SYSTEM 
Self‐emulsifying drug delivery systems(SEDDSs).-Self‐micro‐emulsifying drug delivery
systems (SMEDDSs). Both SEDDSs and SMEDDSs have different characteristics associated with improved drug release properties.SEDDS formulations will be having the simple binary systems which include lipophilic phase and drug, or lipophilic phase,surfactant and drug. And they are having the Generally Conventional SEDDS are generally prepared in a liquid form. They may create a number of disadvantages like high production costs, low stability an
portability, un alterable drugs or excipients precipitation may also be problematic. So to avoid these disadvantages,an alternative approach Solid-Self emulsifying drug delivery system was developed. S-SEDDS are prepared by solidification of liquid/semisolid self emulsifying (SE) ingredients into powders.They may have the combined advantages ofSEDDS (i.e.enhanced solubility and bio availability) and solid dosage forms (e.g.low production cost, convenience of process control, high stability and reproducibility,better patient compliance4.droplet size in the range of 200nm-300nm and the dispersion has a turbid appearance3. And also the concentration of oil is 40-80% in SEDDS.-The formulation of a SMEDDS requires the use of a co‐surfactant to make amicroemulsion. And they are character
rized byhaving droplet size below 50nm, and the dispersion has an optically clear-to-translucent appearance. And the concentration of oil in SMEDDS is less than 20 %.