scientists are developing their own, very promising
option of drug formulation to fight against tuberculosis.
Initial tests on animals have proved that it is possible
to significantly increase therapy efficiency and to
reduce side effects. The so-called liposomes - tiny
lipidic corpuscles "filled with" drug substance
- allow to achieve this goal.
scientists have learned to synthesize new antituberculosis
antibiotic drug formulation - liposomal rifampicin.
Tests on laboratory animals have brought out clearly
that the liposomal preparation is twice as efficacious
as ordinary rifampicin. The point is that the researchers
suggest that antibiotic should not be used by itself,
but enclosed into lipidic containers - liposomes.
The idea of using liposomes as a vehicle for drug
substance delivery into the patient's organism seems
very appealing in general, and attempts to develop
drug formulation of such kind have been made for years.
On the one hand, the walls of these microscopical
corpuscles (the diameter normally being less than
1 micron) are made of natural lipides - approximately
the same as the ones making part of cellular membranes
of human beings. Inside the liposomes, as well as
between lipidic layers if liposomes are multilayer
(like an onion, for example), there is either water
or solution, in this case it is antibiotic solution.
If antibiotic preparation (such as rifampicin) is
hydrophobic, i.e. water-repellent, then it is embedded
inside the layers between lipide molecules. At the
same time, the preparation inside liposomes is less
toxic for human beings and is better protected from
destruction by blood enzymes.
If a patient respires the solution or, to be more
precise, the suspension of such corpuscles, then the
major part of liposomes together with the contents
will get directly to the lungs, which is certainly
very important for treatment of pulmonary forms of
tuberculosis. The major part of antibiotic will make
its way precisely to the target - into pulmonary macrophages,
and this is very good. The reason is, firstly, because
it is in the macrophages that mycobacteria of tuberculosis
normally "settle down".
Secondly, macrophages are intended by nature to "devour"
large alien objects and to destroy them. Alas, this
does not work in case of tuberculosis pathogenes -
they penetrate macrophages, but feel quite comfortable
But when such infected macrophage "eats up"
a drug-containng liposome, the drug would kill the
harmful mycobacteria. Therefore, in this case the
liposome acts as a peculiar Trojan horse stuffed with
The scientists failed so far to implement this remarkable
idea for a rather trivial reason - they failed to
produce satisfactory liposomes filled with rifampicin.
Clinical picture requires a stable preparation to
be well-preserved. That means that liposomes should
be dried up - so that it only remained to add water
to the ampoule and to stir it up before use. The liposomes
suspension should be received, the liposomes being
the same as before drying. Besides, the major part
of antibiotic should be inside liposomes - otherwise,
the entire undertaking loses meaning.
Specialists of the Minsk Institute of Biophysics and
Cellular Engineering (National Academy of Sciences
of Belorus) have managed to overcome these problems.
The method they developed and patented allows to include
the major part (up to 80 percent) of rifampicin in
liposomes, and the liposomes themselves (previously
frozen and dried up in vacuum) are stable enough.
Anyway, they can bear storage within 18 months and,
according to the authors, can be well rehydrated.
Simply speaking, in water they form homogeneous suspension
It should be noted that the researchers have managed
to carry out a number of preclinical trials of the
liposomes. They have found out that potential liposomic
preparation is non-toxic and does not cause allergy.
Experimental tuberculous infection model on mice has
proved that it is 2.5 times more efficacious that
an ordinary antibiotic solution. However, the scientists
did not have time to complete preclinical trials -the
project funding was suspended.
information: S.V. Konev, Academician of the National
Academy of Sciences of Belarus, Professor, Head of
Laboratory of Biophysics and Cellular Engineering,
Institute of Biophysics and Cellular Engineering,
National Academy of Sciences of Belarus (Minsk), Tel.:
(0172) 84-17-49, 84-22-52, Fax: (0172) 84-23-59, firstname.lastname@example.org