To treat hypertension around 75% of patients will require combination therapy for which administration of lisinopril
and indapamide could be of practical use. Lisinopril has a low oral bioavailability (around 25%) with large intersubject
variability (6-60%), due to slow absorption. In order to improve drug permeability, encapsulation of the drugs
within nanoparticles (NPs) has demonstrated great potential. For this reason we have prepared hard capsules containing
both drugs: indapamide and lisinopril-loaded chitosan (CS) nanoparticles. The mucoadhesive characteristics of CS-NPs
will prolong the residence time of lisinopril in contact with the intestinal membrane thereby increasing its oral bioavailability.
Moreover, for their quantification a reversed-phase HPLC method is developed and validated using a C18 column.
The mobile phase is prepared with methanol:water (50:50, v/v) including triethylamine (0.1% of total volume) and adjusted
at pH 3.1. The calibration curves are linear over the ranges 16-24 µg.mL-1 for lisinopril and 8-12 µg.mL-1 for indapamide.
Intra-day precision results in %RSD ranging 0.74-1.86 for lisinopril and 0.60-1.91 for indapamide. Recovery results
obtained for lisinopril and indapamide range 98.22-102.34% and 97.35-101.00%, respectively. The LOD and LOQ
are 0.4 µg.mL-1 and 1.4 µg.mL-1 for lisinopril, and 0.5 µg.mL-1 and 1.5 µg.mL-1 for indapamide. The HPLC method is
simple, easy to apply, rapid, with UV detection, and allows for quality control of the new formulation developed. The
method can be applied for the quantification of this drug combination in medicinal products.