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Taste is a perception on which lies the fate of oral pharmaceuticals. Many orally
administered drugs elicit a bitter taste. Good taste and flavor are critical in medication
compliance, particularly in children in whom the acceptability of a medicament and hence its ease
of administration can be greatly affected by taste. A great deal of effort during
the development and marketing of pediatric formulations is thus expended on
improving their palatability. For these patients, medicaments are typically provided in liquid
forms, such as solutions, emulsions, and suspensions and recently as child-friendly
chewable tablets, fast melt tablets or effervescent tablets (Verma and Garg, 2000; Kuchekar et al., 2001; and Fu et al., 2004), which usually permit perceptible exposure of the bitter drug
to the taste bud. As the range of oral dosage forms available to patients continues to
increase, the issue of taste acceptability becomes increasingly
important. Conventional
taste-masking techniques, such as the use of sweeteners, amino acids, and flavoring
agents often are unsuccessful in masking the taste of highly bitter drugs, and consequently,
other techniques are being exploited for effectively masking the bitter taste (Douroumis et al., 2007). Nalidixic acid is a widely used antibacterial drug, but it is very bitter and as yet
no taste-masked preparation that might be useful in pediatric patients is available in
the market. Although pleasantly flavored liquid oral suspensions are available, they are
not completely taste-masked. Therefore, to provide this drug in a more acceptable and
patient compliant palatable form, an attempt has been made, in the present study, to mask
its bitter taste and formulate it into taste-masked liquid oral suspension.
Microspheres were prepared by solvent evaporation technique with
necessary modifications (Lorenzo-Lamosa et
al., 1997). Accurately weighed but varying
amounts of Eudragit E-100 was dissolved in 10 mL of acetone over a cyclomixer, and
accurately weighed drug was added in the polymer solution. 50 mg of magnesium stearate was
then added to the solution of polymer and drug in acetone. The organic phase was
poured drop-wise to 25 mL of 1:1 mixture of light and heavy liquid paraffin with vigorous
stirring over a mechanical stirrer. High stirring rates of approximately 4,000 rpm were
employed to obtain microspheres of smaller size. Stirring was continued for eight hours. 20 mL
of hexane was added to the stirred contents. The batch was filtered and washed thrice
with hexane, 10 mL each, to remove any adhering liquid paraffin from the surface
of microspheres. Then, several washings with distilled water were given to remove
any unentrapped drug on the surface of the microspheres. This was followed by vacuum
drying of the microspheres overnight at room temperature. Several batches of microspheres
were prepared by varying drug-polymer ratio, keeping all other formulation factors constant. |
