This document summarizes the development and evaluation of an Amphotericin B topical microemulsion formulation for the treatment of invasive fungal infections. Isopropyl myristate was selected as the oil phase and Tween 80 and propylene glycol were selected as surfactant and co-surfactant based on drug solubility tests. Pseudo-ternary phase diagrams were used to identify formulations and optimize surfactant/co-surfactant ratios. The best formulation had a globule size of 84.2 nm, permeated skin 2-fold better than drug solution in vitro, showed higher skin retention and anti-fungal activity against Trichophyton rubrum than controls. It was stable for

1. Amphotericin B topical
microemulsion: Formulation,
characterization and evaluation
Presented By : PALAKDEEP KAUR
M. PHARM.( Pharmaceutics)
170740005
Department of Pharmaceutical Sciences and Technology, MRSPTU , Bathinda.

2. This article was published by Elsevier under journal of Colloids and
Surface B: Biointerfaces
Citation : 60 times
References : contains 64 references
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3. ABSTRACT
The present studies were designed to develop a microemulsion (ME) formulation of
Amphotericin B (Amp B) for the treatment of invasive fungal infections. The oil phase was
selected on the basis of drug solubility whereas the surfactant and co-surfactant were
screened and selected on the basis of their oil solubilising capacity as well as their
efficiency to form ME. Pseudo-ternary phase diagrams were constructed and on the basis
of ME existence ranges various formulations of Amp B were developed. The influence of
surfactant and co-surfactant mass ratio (S mix) on the ME formation and permeation of ME
through excised rat skin was studied. The optimized formulation (ME 7) consisting of 0.1%
(w/w) Amp B, 5% (w/w) Isopropyl Myristate and 35% (w/w) S mix (3:1, Tween 80 and
Propylene glycol), has shown a globule size of 84.20 ± 2.13 nm, a poly dispersity index of
0.164 ± 0.031, pH 7.36 ± 0.02 and conductance of 229.3 ± 1.95 S. ME 7 exhibited 2-fold
higher drug permeation as compared to plain drug solution. Besides this, the formulation
was also evaluated for drug content, stability, skin retention, skin sensitivity and anti-fungal
activity. In vitro anti-fungal activity in Trichophyton rubrum fungal species have shown
that ME7 has higher zone of inhibition and the formulation was found stable at 2–8
◦
C and
at room temperature (25 ± 2 ◦
C) for the period of three months. The results indicate that,
the investigated ME may be used as a promising alternative for Amp B therapy.

4. INTRODUCTION
• Amphotericin B (Amp B) is a broad spectrum
polyene macrolide antifungal antibiotic mainly used
for the treatment of invasive fungal infections.
• Amp B remains “gold standard” drug of choice for
the treatment of disseminated mycosis in
immunodepressed patients e.g. AIDS, organ
transplants, cancer chemotherapy and against the
antimony-resistant visceral leshmeniasis.
• Amp B acts on ergosterol, a steroid present in the
membrane of the fungal cells by increasing its
permeability that promotes an ion efflux into the
parasite, thus leading to its death.

5. RATIONALE
• Amp B has poor bioavailability by oral route and its usefulness is
compromised by a high incidence of adverse reactions including fever,
chills, nausea, vomiting, headache and renal dysfunction with associated
anaemia, hypokalemia and hypomagnesaemia when administered via
parenteral route.
• Instead of oral formulation topical application of drug gives better
treatment approach as well as it reduces side effects associated with its
oral administration.
• Owing to poor aqueous solubility, Amp B cannot permeate through the
skin. Therefore, with an aim to enhance the solubility and eventually the
dermal bioavailability of Amp B,ME formulations were prepared. It
increases the dermal penetration and permeation of the drug.
• Owing to the facile and low cost of preparation, ME was opted over other
colloidal counter parts such as liposome's , niosome and nanoparticle .

6. MATERIALS AND METHODS
• Amp B was obtained as a gift sample from Lyka Labs. Pvt. Ltd,
Mumbai, India.
• Capmul MCM C8 was obtained as a gift sample from Abitec
Corporation Limited, Columbus, Ohio.
• Tween 80 and Iso-propyl Myristate (IPM) were purchased from
Loba Chem., Mumbai, India.
• Labrafac Lipofile, Labrasol and Transcutol were obtained as a
gift sample from Colorcon Asia Pvt. Ltd., Goa, India.
• Oleic acid (OA), Lemon oil, Tween 20, Polyethylene Glycol 400
(PEG 400), Isopropyl alcohol (IPA) and Propylene Glycol (PG)
were purchased from Himedia Pvt. Ltd., Mumbai, India.
• Fungal strain Trichophyton rubrum, ATCC Code 28188TM
(KWIK-STIK 0444 P) was purchased from ATCC Micro biologics,
Minnesota, USA.

7. SCREENING OF OILS, SURFACTANTS &
CO-SURFACTANTS FOR MICROEMULSION
Excess amount
of Amp. B
10 ml of each oil,
surf., Co-surf.
added Followed by
centrifugation
Shaken reciprocally
At 25
◦
C, 72 hrs.
9000rpm
10min.
Supernatant
Membrane
filter
(0.45µm)
Spectro-
photometrically
Determined at
405.5nm
filtered
through

8. PREPARATION OF MICROEMULSION
5%(w/w) IPM0.1%(w/w) Amp B
+
3:1 (Tween 80 & PG)
Dissolved in
Using vortex mixer
MIXTURE
Made up to 100% (w/w) with drop wise addition of
double distilled water
Continuous stirring
Amp. B loaded MEs

9. CHARACTERIZATION OF MICROEMULSION
• Droplet size and poly dispersity index (PDI)
• Measurement of viscosity
• Centrifugation
• Measurement of electrical conductivity
• Measurement of pH
• Macroscopic appearance
• % Transparency
• Dye solubility test
• Ex-vivo diffusion study (Preparation of skin , In vitro permeation study,
Data analysis)
• Skin retention study
• Skin sensitivity studies
• In vitro antifungal activity
• Stability of ME
• Statistical analysis

10. RESULTS

13. CONCLUSION
• The Amp B ME was formulated for topical
application and the results of present study clearly
demonstrated the role of ME in effective topical
delivery of Amp B.
• ME7 has shown higher skin deposition, lower skin
irritation and better anti-fungal activity.
• The developed system may provide better remission
from the disease due to localized delivery with
minimal side effects and the data from in vitro study
has been encouraging but further evaluation is
needed to elucidate the clinical efficacy of this
topical dosage form.

14. CRITICAL EVALUATION
POSITIVE POINTS:
1. Screening of excipients were done properly.
2. Explained properly the procedure of formulating microemulsion.
3. Covered almost all the characterization parameters.
4. Skin retention, skin sensitivity and in vitro antifungal activity was
performed properly .
NEGATIVE POINTS:
1. In vivo studies were not performed.
2. Stability results were not given. The author just explained the
procedure for determining stability.
3. The data were not sufficiently explained by Statistical analysis .
4. Skin diffusion was performed by UV spectroscopy but it would be
more authentic had it been done by HPLC.