Original Article
Miltefosine and polyhexamethylene biguanide:
a new drug combination for the treatment of
Acanthamoeba keratitis
Zubeyde A Polat PhD,
1
Julia Walochnik PhD,
3
Andreas Obwaller PhD,
4
Ayse Vural MD,
2
Ayhan Dursun MD
2
and Mustafa K Arici MD
2
Departments of
1
Medical Parasitology and
2
Ophthalmology, Cumhuriyet University School of Medicine, Sivas, Turkey; and
3
Institute of
Specific Prophylaxis and Tropical Medicine, Medical University of Vienna, and
4
Orphanidis Pharma Research GmbH, Vienna, Austria
ABSTRACT
Background: In this study, a series of compounds –
miltefosine, polyhexamethylene biguanide, chlo-
rhexidine and propamidine isethionate – and
combinations of the latter three agents with miltefo-
sine were prepared and used in a rat model for the
topical treatment of Acanthamoeba keratitis.
Methods: The corneas of rats were infected with
Acanthamoeba hatchetti. On the fifth day, all corneas
were microscopically examined in order to deter-
mine the grade of infections. Nine groups were then
prepared: miltefosine (65.12 mg/mL); chlorhexidine
(0.02%); polyhexamethylene biguanide (0.02%),
propamidine isethionate (0.1%), miltefosine plus
chlorhexidine, miltefosine plus polyhexamethylene
biguanide; miltefosine plus propamidine isethionate;
infected control; and a non-infected control group.
The treatment was continued for 28 days. After the
treatment, the corneas were excised and used for
Acanthamoeba culture to investigate the presence of
Acanthamoeba growth. For the determination of cyto-
toxicity of the drugs on L929 cells, colorimetric
assays were performed.
Results: The best treatment results were obtained
from the polyhexamethylene biguanide plus milte-
fosine group; the ratio of fully recovered eyes
was 28.4%. It was proven that the miltefosine–
polyhexamethylene biguanide combination yielded
the highest anti-acanthamoebal activity in that
approximately 86% of the eyes were cleared from
amoebae. The cytotoxicity values of the miltefo-
sine and the control groups were compared with
other groups and found to be statistically different
(P < 0.05).
Conclusion: This in vivo study demonstrates that a
miltefosine–polyhexamethylene biguanide combina-
tion is highly effective for the treatment of Acan-
thamoeba keratitis.
Key words: Acanthamoeba, keratitis, miltefosine, poly-
hexamethylene biguanide, rat keratitis model.
INTRODUCTION
Acanthamoebae are extracellular protozoan organisms
that have been isolated from a variety of environ-
ments. Acanthamoeba keratitis (AK) is a severe
and potentially vision-threatening corneal infection
caused by free-living, pathogenic amoebae belong-
ing to the genus Acanthamoeba.
1
It has been detected
in almost all parts of the world.
2
Risk factors associ-
ated with contact lens wear are now well known: the
combination of epithelial microtrauma, poor contact
lens hygiene and the wearing of contact lenses in
contaminated water environments such as swim-
ming pools, spas and lakes. Insufficient or improper
cleaning and disinfection of contact lenses, including
Correspondence: Assoc. Prof. Dr. Zubeyde Polat, Department of Medical Parasitology, University of Cumhuriyet School of Medicine, 58140 Sivas,
Turkey. Email: zubeydeakin@yahoo.com
Received 4 January 2013; accepted 6 March 2013.
Competing/conflicts of interest: No stated conflict of interest.
Funding sources: This study was supported by Orphanidis Pharma Research GmbH, Vienna, Austria.
Clinical and Experimental Ophthalmology 2014; 42: 151–158 doi: 10.1111/ceo.12120
© 2013 Royal Australian and New Zealand College of Ophthalmologists