Molecularly-imprinted polymer-base bulk optode for the determination of ivabradine hydrochloride in Procoralan®

IVH may be administered orally twice per day for treating heart failure, sinus rhythm, heart-related chest pain and angina pectoris, and its overdose may cause problems such as blurred vision, uncontrolled blood pressure, prolonged bradycardia, and others. A molecularly imprinted polymer-based bulk optode, miptode, was constructed for the determination of ivabradine hydrochloride (IVH) in its pharmaceutical preparation Procoralan®. The molecularly-imprinted polymers (MIPs) were prepared in different ratios, and MIP3 had the highest imprinting factor (1.6) as an ionophore in the miptode preparation. The miptode was prepared using weight ratios of 30% PVC polymer, 62% nitrophenyl octyl ether (NPOE) plasticizer, 6% MIP3 ionophore, 1% tetraphenyl borate derivative (TPB) ion-exchanger, and 1% ETH7075 chromoionophore; this miptode exhibited an absorbance increase at 530 nm in the concentration range of 10-2-10-5 M with a detection limit of 3.1 μM using Tris-HCl buffer of pH 7.2. The miptode was imaged using AFM, and showed the dissolution of all components except MIP particles which exhibited restricted solubility. However, the incorporation of MIP3 as an ionophore improved the selectivity coefficient over the interfering species that may exist in the pharmaceutical formulation to an extent that was not reported before; e.g. coefficients of IVH over sodium, magnesium, and glucose were improved by 5, 4 and 2 orders, when compared to the previous sensor that operated with the molecular interaction mechanism. The selectivity improvement in miptode is due to the Key-Lock fitting (host-guest molecular recognition) between the MIP particles and the template IVH molecule which is transduced with the ion-exchange process of the chromoionophore. The miptode has a response time of 1-2 minutes, and a reliable lifetime of two months. The miptode was applied successfully for the determination of IVH in the pharmaceutical preparation Procoralan® with recovery values of 89-99.8% with low standard deviations of <1.2.

Molecularly Imprinted Electrochemical Sensor-Based Fe2O3@MWCNTs for Ivabradine Drug Determination in Pharmaceutical Formulation, Serum, and Urine Samples

Ivabradine hydrochloride (IVR) is a medically important drug because of its ability to lower the heart rate. Techniques reported for IVR determination were expensive, laborious, besides being of poor selectivity. In this study, iron oxide @ carbon nanotube (Fe₂O₃@MWCNTs) nanocomposite and molecularly imprinted polymer (MIP) were synthesized and used in the fabrication of carbon paste electrodes (CPEs) for the potentiometric detection of IVR in biological and pharmaceutical samples. CPEs of the best sensor were formulated from graphite (41 wt%) as a carbon source, MIP (3 wt.%) as an ionophore, Fe₂O₃@MWCNTs (5 wt%) as a modifier, and nitrophenyl octyl ether (NPOE, 51 wt.%) as a conductive oil so-called plasticizer. The best sensor exhibits a Nernstian slope (response) of 56 mV decade^–1 within the IVR concentration range from 1.0 × 10^–3 M to 9.8 × 10^–8 M with high selectivity against interfering species (ascorbic, maltose, glucose, lactose, dopamine, glycine) over those reported earlier. The use of Fe₂O₃@MWCNTs together with MIP in the electrode formulation was found to improve the limit of detection (LOD) from 630 to 98 nM along with high reversibility, a short response time of 30 s, and a good lifetime of more than 2 weeks. The sandwich membrane (SMM) method was used to quantify the H-bonding complexing strength of the MIP binding sites for IVR with Log β_ILn = 11.33. The constructed sensors were successfully applied for the IVR determination in blood serum, urine, and commercial formulations (Savapran^®) with high sensitivity.