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Shubam et al. European Journal of Biomedical and Pharmaceutical Sciences
373
MICROEMULSION: PHYTOCHEMICAL USED IN NEW PREPERATIONS
Shubam Sehgal*, Tanvay Jaithliya, Manooj Kumar, Mohd. Shabaz Khan and Zubair, Ranjeet Kumar
Faculty of Pharmaceutical Sciences Mewar University, Gangrar, Chittorgarh, 312901.
Article Received on 05/03/2018 Article Revised on 26/03/2018 Article Accepted on 16/04/2018
INTRODUCTION
Microemulsion is a system of water, oil and an
amphiphile which is a single optically isotropic and
thermodynamically stable liquid solution”. In some
respects, micro emulsions can be considered as small-
scale versions of emulsions, i.e., droplet type dispersions
either of oil-in- water (o/w) or of water-in-oil (w/o), with
a size range in the order of 5−50 nm in drop radius. Such
a description, however, lacks precision since there are
significant differences between micro-emulsion and
ordinary emulsions (or macroemulsions). In particular, in
emulsions the average drop size grows continuously with
time so that phase separation ultimately occurs under
gravitational force, i.e., they are thermodynamically
unstable and their formation requires input of work. The
drops of the dispersed phase are generally large (> 0.1
μm) so that they often take on a milky, rather than a
translucent appearance. For micro-emulsion, once the
conditions are right, spontaneous formation occurs. As
for simple aqueous systems, microemulsion formation is
dependent on surfactant type and structure. If the
surfactant is ionic and contains a single hydrocarbon
chain (e.g., sodium dodecylsulphate, SDS) micro-
emulsion are only formed if a co- surfactant (e.g., a
medium size aliphatic alcohol) and/or electrolyte (e.g.,
0.2 M NaCl) are also present. With double chain Ionics
(e.g., Aerosol-OT) and some non-ionic surfactants a co-
surfactant is not necessary. This results from one of the
most fundamental properties of micro- emulsion, that is,
an ultra-low interfacial tension between the oil and
water phases, γ o/w. The main role of the surfactant is
to reduce γ sufficiently − i.e., lowering the energy
required to o/w increase the surface area − so that
spontaneous dispersion of water or oil droplets occurs
and the system is thermodynamically stable.
Defination and History
Micro emulsions, or μ-emulsions, are isotropic mixtures
of oil, water and surfactant; usually with a co-surfactant
and the oil being a mixture of different hydrocarbons and
olefins.[1]
The concept of micro-emulsion was introduced by
Professor, Jack H. Shulman at Columbia University in
1959. The definition of a microemulsion have varied
with time and location, but the more commonly accepted
view is that of a “system of water, oil and amphiphile
which is a single optically isotropic and
thermodynamically stable liquid solution”[2] and that in a
microemulsion the surfactant is located at a certain
boundary between the oil and aqueous phases, giving the
microemulsion a definite microstructure. The above
mentioned surfactant molecules, in most cases, comprise
of a polar head which make up a small fraction of the
molecular volume and a non-polar tail. These two
regions allow them to interact with the polar aqueous
phase and the non-polar oil phase. Surfactant molecules
associate into different forms, including spherical
micelle, rod micelle laminar phase and hexagonal phase,
to minimise the Gibbs free energy of the system and to
“optimise solvation requirements”.
Advantages and Disadvantages
Advantages of Microemulsion as Oral Drug Vehicle
Increases the rate of absorption.
SJIF Impact Factor 4.382
Review Article
ejbps, 2018, Volume 5, Issue 5 373-376.
European Journal of Biomedical
AND Pharmaceutical sciences
http://www.ejbps.com
ISSN 2349-8870
Volume: 5
Issue: 5
373-376
Year: 2018
*Corresponding Author: Shubam Sehgal
Faculty of Pharmaceutical Sciences Mewar University, Gangrar, Chittorgarh, 312901.
ABSTRACT
Microemulsion is a clear transparent, thermodynamically stable dispersion of oil and water, stabilized by
interfacial film of surfactant frequently in combination with a co-surfactant. Recently there has been a
considerable interest for microemulsion formulation, for the delivery of hydrophilic as well as lipophilic drug as
drug carriers because of its improved drug solubilisation capacity, long shelf life, ease of preparation and
improvement of bioavailability. In this present review, we have discuss biopharmaceutical aspects, advantages,
disadvantage, theories, formulations, marketed lipid based formulations, factors affecting formulation and phase
behaviour, preparations, characterization and pharmaceutical application of Microemulsion.
KEYWORDS: Microemulsion is a clear pharmaceutical application of Microemulsion.
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Shubam et al. European Journal of Biomedical and Pharmaceutical Sciences
374
Eliminates inter-subject and intra-subject variability
in absorption.
Helps to solubilize lipophilic drug.
Provides a aqueous dosage form for water insoluble
drugs.
Thermodynamically stable system, so for long time
they can remain stable without any type of
aggregation or creaming.
Releases drug in controlled fashion.
Minimizes first pass metabolism.
Increases bioavailability.
Helpful in taste masking.
Provides protection from hydrolysis and oxidation as
drug in oil phase in O/W microemulsion is not
exposed to attack by water and air.
Ease of preparation due to spontaneous formation.
Scale up process is also easy.[3]
Disadvantages (limitations) of Microemulsion as Oral
Drug Vehicle
Use of a large concentration of surfactant and co-
surfactant necessary for stabilizing the Nano
droplets.
Limited solubilizing capacity for high-melting
substances.
The surfactant must be nontoxic for using
pharmaceutical applications.
Microemulsion stability is influenced by
environmental parameters such as temperature and
pH. These parameters change upon microemulsion
delivery to patients.
For unique dosage preparation in gelatine capsules,
it may produce softening or hardening effect on
capsule shell, so for long term storage it is
undesirable.[3]
Phytochemicals as Micro Emulsion
In modern drug discovery era, various chemically
synthesized new molecules are approved by FDA and are
coming on the market, having wide therapeutic efficacy,
but the adverse effects are associated with this therapy
causes serious adverse effects which could be life
threatening. Conventional therapy provides non-
targetability in tissues and organs due to peak and valley
fluctuations, and a frequent dose of administration can
produce troublesome for allopathic medicines lead to
poor patient compliance. The controlled release drug
delivery system provides drug release at a controlled rate
and maintains the overall therapeutic concentration of the
drug in the body. In ancient times, herbal remedies and
natural extract are consumed by people to cure various
diseases. These herbal remedies contain hundreds of
phytoconstituents present, which is working
simultaneously against the disease. In recent times, the
interest of people in phytopharmaceuticals has been
increasing day-by-day among physicians and patients,
and it is evident from the global market of herbal
medicine and phytopharmaceuticals that has increased
from $18 billion from 2005 and $26 from 2011. Various
dietary products and supplements are also derived from
the natural origin are also gaining more interest in the
industry and the global market for phytopharmaceuticals.
Some phytoconstituents derived from the natural origin
are having a poor solubility and low bioavailability
resulting in a narrow therapeutic index, which hinders his
novel efficiency, so formulation scientist is working on
targeting and controlled drug release of
phytoconstituents to provide better therapeutic effect and
increased patient compliance.
List of some micro herbal emulsions: Table 1.[7]
Phytoconstituent
Chemical nature and source
Pharmacological activity
Clinical significance
Curcumin
Diarylheptanoid, obtained from
Curcuma longa
Anticancer activity, anti-
inflammatory activity
Improved permeation and enhancement
ratio via transdermal delivery
Triptolide
Diterpenoid
triepoxide, obtained from
Chinese herb, Tripterygium
wilfordii
Useful inautoimmune
disorders, antineoplastic
Microemulsion based hydrogel provides
improved percutaneous permeability and
better-sustained release profile
Psoralen
Counmarin glycoside, obtained
from Psoralea corylifolia
Useful in skin disorders,
leprosy, and anti-
inflammatory
Topical delivery via microemulsion
provides better invivo anti-inflammatory
effect
Silybin
Flavolignans, obtained from
Silybum marianum
Broad spectrum
activity against
human prostate
adenocarcinoma cells
Microemulsion vehicle shows
prolonged release profile as compared to
silymarin solution
Docetaxel
Taxol comound, obtained from
taxus
pecies (Taxusbacatta, Taxus
brevifolia)
Broad spectrum
antimitotic compound
against all types of cancer
Docetaxel microemulsion
provides improved apical to
basolateraltransport across Caco-2 cells
Puerarin
Isoflavone compound, obtained
from Radix puerariae
Useful in cardiovascular
disorders
AUC0-∞ was 15.82-ld higher in
microemulsion as compared to puerarin
suspension
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Shubam et al. European Journal of Biomedical and Pharmaceutical Sciences
375
Pharmaceutical Applications of Micro-emulsion
Parenteral Delivery
Parenteral administration (especially via the intravenous
route) of drugs with limited solubility is a major problem
in industry because of the extremely low amount of drug
actually delivered to a targeted site. Microemulsion
formulations have distinct advantages over
macroemulsion systems when delivered parenterally
because of the fine particle microemulsion is cleared
more slowly than the coarse particle emulsion and,
therefore, have a longer residence time in the body. Both
O/W and W/O microemulsion can be used for parenteral
delivery. The literature contains the details of the many
microemulsion systems, few of these can be used for the
parenteral delivery because the toxicity of the surfactant
and parenteral use. An alternative approach was taken by
Von Corsewant and Thoren in which C3-C4 alcohols
were replaced with parenterally acceptable co-
surfactants, polyethylene glycol (400) / polyethylene
glycol (660) 12-hydroxystearate / ethanol, while
maintaining a flexible surfactant film and spontaneous
curvature near zero to obtain and almost balanced middle
phase microemulsion. The middle phase structure was
preferred in this application, because it has been able to
incorporate large volumes of oil and water with a
minimal concentration of surfactant.[4]
Oral Delivery
Microemulsion formulations offer the several benefits
over conventional oral formulation for oral
administration including increased absorption, improved
clinical potency and decreased drug toxicity. Therefore,
microemulsion have been reported to be ideal delivery of
drugs such as steroids, hormones, diuretic and
antibiotics. The microemulsion droplets dispersed in the
gastrointestinal tract provide large surface area and
promote a rapid release of dissolved form of the drug
substance and/or mixed micelles containing drug
substance, and they may be also responsible for
transporting the drug through the unstirred water layer to
the gastrointestinal membrane for absorption. In addition
to the enhanced dissolution of drugs, another factor
contributing to the increasing bioavailability is that
lymphatic transport is responsible for a portion of the
entire drug uptake as well. The lipid composition of
system may be related to facilitate the extent of
lymphatic drug transport by stimulating lipoprotein
formation and intestinal lymphatic liquid flux.
Pharmaceutical drugs of peptides and proteins are highly
potent and specific in their physiological functions.
However, most are difficult to administer orally. With on
oral bioavailability in conventional (i.e. non-
microemulsion based) formulation of less than 10%, they
are usually not therapeutically active by oral
administration. Because of their low oral bioavailability,
most protein drugs are only available as parenteral
formulations. However, peptide drugs have an extremely
short biological half life when administered parenterally,
so require multiple dosing.33A microemulsion
formulation of cyclosporine, named Neoral® has been
introduced to replace Sandimmune®, a crude oil-in-
water emulsion of cyclosporine formulation. Neoral® is
formulated with a finer dispersion, giving it a more rapid
and predictable absorption and less inter and intra patient
variability.[5]
Topical Delivery
Topical administration of drugs can have advantages
over other methods for several reasons, one of which is
the avoidance of hepatic first pass metabolism of the
drug and related toxicity effects. Another is the direct
delivery and targetability of the drug to affected area of
the skin or eyes. Both O/W and W/O micro-emulsion
have been evaluated in a hairless mouse model for the
delivery of prostaglandin E1. The micro-emulsion were
based on oleic acid or Gelucire 44/14 as the oil phase and
were stabilized by a mixture of Labrasol (C8 and C10
polyglycolysed glycerides) and Plurol Oleique CC 497 as
surfactant. Although enhanced delivery rates were
observed in the case of the o/w microemulsion, the
authors concluded that the penetration rates were
inadequate for practical use from either system. The use
of lecithin/IPP/water microemulsion for the transdermal
transport of indomethacin and diclofenac has also been
reported. Fourier transform infra red (FTIR)
spectroscopy and differential scanning calorimetry
(DSC) showed the IPP organogel had disrupted the lipid
organisation in human stratum corneum after a 1 day
incubation.[6]
CONCULSION
Microemulsion is a powerful formulation tools for poorly
soluble API‟s, both for the oral and topical
administration routes. The availability of efficient, non-
toxic surfactants and co- surfactant now makes them a
very attractive and feasible option to overcome the
bioavailability problems frequently encountered in the
development of modern drugs. Drug delivery through
microemulsion is a promising area for continue research
with the aim of achieving controlled released with
enhancing bioavailability and for drug targeting to
various site in the body.
REFERENCES
1. Shah, D. O., Ed. „Surface Phenomena in Enhanced
Recovery‟ Plenum Press, 1981, New York. 2 J.H.
Schulman, W. Stoeckenius, L.M. Prince,
Mechanism of formation and structure of micro
emulsions by electron microscopy, J. Phys. Chem.,
1959; 63: 1677–1680.
2. International Bulletin of Drug Research.
EMERGING TREND OF MICROEMULSION IN
FORMULATION AND RESERACH
SARKHEJIYA NAIMISH A.*1, NAKUM MAYUR
A.1, PATEL VIPUL P.2, ATARA SAMIR A.
DESAI THUSARBINDU R, 1(1): 54-83, 54.
3. Corswant VC, Thoren P and Engstrom S,
Triglyceride-based Microemulsion by Intravenous
Administration of Sparingly Soluble Substances. J.
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Shubam et al. European Journal of Biomedical and Pharmaceutical Sciences
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Pharm. Sci., 1998; 87: 200-208.
4. Kovarik JM, Muller EA, Van Bree JB, Tetzioff W
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Variability in Cyclosporin Pharmacokinetics from
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83: 444-452.
5. Schmalfun U, Neubert R and Wohlrab W,
Modification of Drug Penetration into Human Skin
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6. International Bulletin of Drug Research., 1(1):
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7. Dilpreet Singh application of NDDS in enhancing
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