INVESTIGADORES
JIMENEZ KAIRUZ Alvaro Federico
congresos y reuniones científicas
Título:
Swellable drug polyelectrolite matrices: preliminary rheological studies on carbomer-ciprofloxacin-sodium systems
Autor/es:
CHANAMPA, L.; RESSIA, J.; JIMENEZ KAIRUZ, AF.; VALLÉS, EM.
Lugar:
Córdoba
Reunión:
Congreso; 1ra. Reunión de Ciencias Farmacéuticas, RICiFa; 2010
Institución organizadora:
Dpto de Farmacia, FCQ-UNC - CONICET
Resumen:
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Introducción
Many controlled drug delivery
systems have been introduced in pharmacotherapy along time exhibiting a number of advantages over conventional
dosage forms. In the early works, novel swellable drug polyelectrolyte matrices
(SDPM) obtained by compaction of powdered complexes of a polyelectrolyte (PE)
fully or partially neutralized with a ionizable drug (D) have been developed
using current tableting technology(1-2). Unlike traditional
swellable hydrophilic matrices, SDPM?s contain a molecular dispersion of D in
the mass of the matrix since D is ionically bonded to the functional groups of
PE as a (PE-D) complex which is relevant to obtain: drug controlled release, drug
chemical stability and aqueous compatibility increase, and/or multiparticulate
delivery systems. Extended release SDPM, containing Ciprofloxacin (500mg) ?
Carbomer complex, were prepared and evaluated by Bermudez et al. (3).
They showed that water sorption and release properties were highly sensitive to
material composition. It?s known that rheological studies can offer detailed
structural information about dispersed polymeric system.
In this way, a preliminary rheological
study was conducted to associate the viscoeleastic characteristics (G?, G??,
Tan α) of the hydrated matrices as a function of Na+ and water
contents with the water sorption and Ciprofoxacin release behavior from SDPM.
Materials
and methods
(CB-Cip)50
complexes were prepared (subindex 50 meaning the Cip molar percentage with
respect to the CB ionizable carboxilic groups). Then, NaOH 1M was added in
order to obtain a molar concentration of 5, 10 and 20% of sodium in the
complexes. The resulting samples, labeled as (CB-Cip)50, (CB-Cip)50Na5,
(CB-Cip)50Na10 y (CB-Cip)50Na20,
were characterized by Differential Scanning Calorimetry (DSC) in a Perkin-Elmer Pyris I calorimeter.
The sodium
contaning complexes were hydrated using physiological solution (PS) at
different concentrations, ranging from 19 to 29% w/w, depending on the ability
of the powdered samples to absorb PS to acquire adequate consistency for being
tested on the rheometer. Rheological characterization was performed in a TA Instruments AR-G2 rheometer, in small amplitude frequency
sweep tests using 25 mm diameter parallel plates, at room temperature. In order
to avoid dehydratation during the test the samples located between the plates
were protected with thin layer of a low viscosity silicon oil.
Results and conclusions
DSC analysis showed that Cip the characteristic fusion peak of neat Cip
(265-268°C) was not observed in any of the (CB-Cip)50Na complexes confirming the complete interaction between CB and Cip. The
complexes showed a narrow window on their capacity to absorb PS in order to
obtain the desired consistency for the rheological analysis. A further addition
of PS caused the formation of a second phase.
From the preparation of the samples for rheological
tests, it was inferred that increasing the sodium concentration on the (CB-Cip)50Na complexes, increases the
capacity of the complexes to absorb PS up to Na contents of about 10%. Higher contents of Na do not further augment the
amount of PS absorbed by the complexes.