A Herb-drug interaction study: Screen the inhibitory effects of Insulin plant extract on rat liver CYP2D6 isoenzyme upon concurrent administration of Aripiprazole

Abstract

Aripiprazole belongs to the atypical antipsychotic category of drug. Cytochrome2D6 (CYP2D6) is one of the prominent enzymes that play a key role in the metabolism of Aripiprazole and further formation of an active metabolite, Dehydroaripiprazole takes place. Patients under the treatment with this potent moiety have been reported with the high blood glucose level as a side effect. In addition to this, literature suggests that the leaves of Insulin plant (Costus igneus) are usually administered by diabetic patients (2-3 times) to manage the sugar level without concerning to the physicians. There might be probability while concurrent administration of (Aripiprazole and Insulin plant leaves), leaves inhibit the enzyme and ultimately Dehydroaripiprazole exhibit poor pharmacological action. Hence, the present work was done to investigate the inhibitory effect of Insulin plant extract (IPE) on CYP2D6, with the co-administration of Aripiprazole (to examine the changes in a metabolite of Aripiprazole). In order to carry out this protocol firstly, IPE was prepared by the successive extraction method. Methanolic extract of Insulin plant was found enriched with the Quercetin, which was used as a marker to carry out this study. Presence of Quercetin was confirmed with the Ultra-violet spectroscopy (UV) and High-performance liquid chromatography (HPLC) analytical methods. Characterization of Aripiprazole was done with the help of different analytical tools such as: HPLC, melting point, and UV. Aripiprazole alone and with the several dilutions of IPE were incubated using isolated rat liver microsome (RLM) and analyzed using HPLC. HPLC data demonstrated that the, mixture of IPE+Aripiprazole (herb and drug in liver microsomes), in comparison to Aripiprazole+RLM (alone drug in liver microsomes) has not shown any significant inhibition of the enzyme, and inhibitory concentration (IC50) value found to be 4.49µg/ml. Therefore this study concluded that IPE has shown safe results even at the highest clinical dose after oral administration i.e., 20-1000µg/ml and did not show any significant CYP2D6 inhibition. Nevertheless, to confirm these observations, inclusion of in vivo studies will be advantageous. As per our knowledge, this is the first attempt made on the detection of Herb- Drug interactions (HDI’S) between Insulin plant and Aripiprazole.