Simultaneous estimation of novel antihypertensive drug combination efonidipine hydrochloride and telmisartan using liquid chromatographic method

Figures & data

Figure 1. Chemical structure of efonidipine hydrochloride.

Figure 2. Chemical structure of telmisartan.

Figure 3. UV spectra of both drugs for selection of analytical wavelength.

Figure 4. Chromatogram of EFD and TEL in optimized mobile phase.

Table 1. Regression analysis of calibration curve of EFD and TEL.

Parameter	Efonidipine Hydrochloride (EFD)	Telmisartan (TEL)
Linearity Range (µg/ml)	0.2 – 15	0.2 – 15
Slope	19329.33	84638.00
Standard Deviation of Slope	312.20	940.99
Intercept	7737.33	93767.33
Standard Deviation of Intercept	718.00	2552.68
Correlation Coefficient (r^2)	0.998	0.996

Table 2. Intermediate precision of EFD and TEL.

	Efonidipine Hydrochloride				Telmisartan
	Interday Precision		Intraday Precision		Interday Precision		Intraday Precision
Concentration (µg/ml)	Area ± SD (n = 3)	%RSD	Area ± SD (n = 3)	%RSD	Area ± SD (n = 3)	%RSD	Area ± SD (n = 3)	%RSD
0.2	5140.33 ± 40.20	0.78	5065.00 ± 26.29	0.52	55161.00 ± 24.64	0.04	55692.67 ± 439.06	0.79
5	104618.67 ± 844.89	0.81	104837.67 ± 664.10	0.63	537294.33 ± 834.20	0.16	537932.00 ± 2379.48	0.44
15	298126.33 ± 2817.55	0.95	298088.00 ± 2712.39	0.91	1353829.67 ± 7587.58	0.56	1364513.00 ± 7146.37	0.52

Table 3. Summary of validation parameter of EFD and TEL.

Parameter	Efonidipine Hydrochloride (EFD)	Telmisartan (TEL)
Rt	7.35	4.97
Detection Limit (µg/ml)	0.12	0.10
Quantitation Limit (µg/ml)	0.37	0.30
Trueness (accuracy) (%)	98.30 – 99.49	98.07 – 99.26
Precision (%RSD)
Intraday Precision (n = 3)	0.52 – 0.91	0.44 – 0.79
Interday Precision (n = 3)	0.78 – 0.95	0.04 – 0.56
Repeatability Study (%RSD) (n = 6)
Injection Repeatability	0.66	0.42
Scanning Repeatability	0.94	0.55
Assay	100.04%	99.26%
Specificity	Specific	Specific
Robustness	Robust	Robust
Solution Stability	Stable	Stable

RSD is Relative Standard Deviation and “n” is number of determinations.

Table 4. Robustness studies of EFD and TEL.

			%RSD (n = 3)
			Efonidipine Hydrochloride (EFD)		Telmisartan (TEL)
Parameters	Normal Condition	Change in Condition	Rt	Area	Rt	Area
Change in Wavelength	251 nm	250 nm	0.15	0.78	0.23	0.96
		252 nm	0.08	0.70	0.20	0.90
Change in Flow Rate	1 ml/min	0.9 ml/min	0.07	0.75	0.10	0.53
		1.1 ml/min	0.09	0.69	0.12	0.67
Change in Mobile Phase Composition	75:25 v/v	70:30 v/v	0.10	0.32	0.10	0.95
		80:20 v/v	0.17	0.46	0.44	0.82

Figure 5. Chromatogram showing peak of TEL (10 µg/ml) and EFD (10 µg/ml) at 70° C for 4 hours in 0.1 N HCl.

Figure 6. Chromatogram showing peak of TEL (10 µg/ml) and EFD (10 µg/ml) at 70° C for 2 hours in 0.1 N NaOH.

Figure 7. Chromatogram showing peak of TEL (10 µg/ml) and EFD (10 µg/ml) at 70° C for 4 hours in 0.1 N NaOH.

Figure 8. Chromatogram showing peak of TEL (10 µg/ml) and EFD (10 µg/ml) at 70° C for 60 minutes in 3% H₂O_2.

Figure 9. Chromatogram showing peak of TEL (10 µg/ml) and EFD (10 µg/ml) at 70–80° C for 120 minutes.

Figure 10. Chromatogram showing peak of TEL (10 µg/ml) and EFD (10 µg/ml) under UV Light for 24 hours.

Table 5. Result of stability study of proposed method.

			%Amount of Drug Recovered		Rt of Degradant
Sr. No	Types of Stability Study	Condition for Study	EFD	TEL	EFD	TEL
01	Acid Hydrolysis	Heating for 240 minutes at 70° C.	96.21	98.39	-	-
02	Base Hydrolysis	Heating for 120 minutes at 70° C.	45.88	96.03	3.73, 4.51, 6.34	-
03	Base Hydrolysis	Heating for 240 minutes at 70° C.	0.68	96.72	3.77, 4.52, 6.37	-
04	Oxidative Stability	Heating for 60 minutes at 70° C.	72.61	95.40	3.32	-
05	Dry Heat Stability	Heating for 120 minutes at 70- 80° C.	96.87	95.13	-	-
06	Photo Stability	Drug was exposed for 24 hours under UV Light.	97.28	98.93	-	-

Table 6. Result of system suitability parameters for developed method of EFD and TEL.

Parameters	Standard Value	Calculated Value
		Efonidipine Hydrochloride (EFD)	Telmisartan (TEL)
Theoretical Plate	NLT 2,000	4,480.48	2,737.6
Tailing Factor	NMT 2	1.05	0.98
Retention Time	-	7.03	4.84
Resolution	NLT 2	4.92