RP-HPLC Method Development and
Validation for Simultaneous Estimation of Prazosin and Polythiazide in Bulk and
Pharmaceutical Dosage Form
Uttam Prasad Panigrahy*, K. Naga
Vishnu Kumari, T. Ram Mohan Reddy, K. Abbulu
Department of
Pharmaceutical Analysis and Quality Assurance, CMR College of Pharmacy,
Kandlakoya, Medchal, Hyderabad-501401,
Telangana, India
*Corresponding
Author E-mail: uttampanigrahy@gmail.com
ABSTRACT:
A new isocratic
RP-HPLC method was developed and
validated for simultaneous estimation of Prazosin and Polythiazide in
bulk and pharmaceutical dosage form with stability studies as per ICH
guidelines. In this method Symmetry C18 column (150mm×4.6mm, 5mm particle size), Waters Alliance e2695 HPLC system with PDA detector
and the mobile phase contained a mixture of 0.01M Potassium dihydrogen
orthophosphate buffer (pH adjusted to 3.48 with orthophosphoric acid) and
Acetonitrile (50:50, v/v) was used. The flow rate was set to 1mL/min with the
responses measured at 265nm. The retention time of Prazosin and Polythiazide was
found to be 2.989min and 2.134min respectively with resolution of 5.1.
Linearity was established for Prazosin is 25-150µg/mL and for Polythiazide is
6.25-37.5µg/mL with correlation coefficients (r2=0.999). The
percentage recoveries for Prazosin are 100.34% and Polythiazide is 100.32% respectively.
Prazosin and Polythiazide are more sensitive towards
acidic, basic and oxidative degradation condition. The developed method was
successfully applied for the quantification of Prazosin and Polythiazide in
bulk and pharmaceutical dosage form.
KEYWORDS: Prazosin, Polythiazide,
RP-HPLC, ICH.
INTRODUCTION:
Prazosin is a selective α-1-adrenergic
receptor antagonist used to treat hypertension. It has also been used to
decrease urinary obstruction and relieve symptoms associated with symptomatic
benign prostatic hyperplasia1. Prazosin
is chemically known as [4-(4-Amino-6, 7-dimethoxyquinazolin-2-yl) octahydroquinoxalin-1(2H)-yl] (furan-2-yl) methanone were shown in
(Figure 1).
Polythiazide is a diuretic which inhibits active chloride re-absorption
at the early distal tubule via the thiazide-sensitive Na-Cl co-transporter
(TSC), resulting in an increase in the excretion of sodium, chloride, and
water. It also inhibits sodium ion transport across the renal tubular
epithelium through binding to the thiazide sensitive sodium-chloride
transporter. This results in an increase in potassium excretion via the
sodium-potassium exchange mechanism. The antihypertensive mechanism of
polythiazide may be mediated through its action on carbonic anhydrases in the
smooth muscle or through its action on the large-conductance calcium-activated
potassium (KCa) channel, also found in the smooth
muscle2. Polythiazide is chemically known as 6-chloro-2-methyl-1, 1-dioxo-3-(2, 2,
2-trifluoroethylsulfanylmethyl)-3, 4-dihydro-1λ6, 2,
4-benzothiadiazine-7-sulfonamide was shown in (Figure
2).
Prazosin and Polythiazide is a fixed dose combination drug for
treatment of hypertension. Literature review reveals that very few
analytical methods has been reported for the determination of Prazosin and Polythiazide individually and with
other combinations which includes high performance liquid chromatography (HPLC)3-19,
UV-Visible-Spectrophotometric20-23 and LC-MS24,25. The
present study was intended to develop a new validated method for the
simultaneous estimation of Prazosin and
Polythiazide with forced degradation studies as per ICH guidelines26.
MATERIALS AND METHODS:
Chemicals and reagents:
Prazosin (API) and Polythiazide (API) was obtained from Synthokem Labs Private Ltd., Hyderabad, India. HPLC grade
of Potassium dihydrogen orthophosphate was obtained from Rankem
Ltd., India and HPLC grade of Acetonitrile was obtained from Merck Specialities
Private Limited, India. HPLC grade of Water and Ortho phosphoric acid
was obtained from Rankem Ltd., India. Minizide 432® capsule contains Prazosin 2mg and Polythiazide 0.5
mg were kindly supplied by Pfizer Labs, Inc.
The
analysis was performed by using a chromatographic system from Waters Alliance
e2695 HPLC system with 2998 PDA detector. The HPLC system was equipped with
Empower 2 software. Denver electronic balances, Ultrasonic bath sonicator (BVK enterprises, India), Digital pH meter (BVK
enterprises, India) and Whatmann filter paper No. 41
(Whatmann International Ltd., England) were used in
the study.
Chromatographic conditions:
Prazosin and Polythiazide
was analysed in
Symmetry C18 column (150mm×4.6mm, 5mm particle
size) column for the chromatographic separation. The mobile phase was composed
of of 0.01M Potassium dihydrogen orthophosphate
buffer (pH adjusted to 3.48 with orthophosphoric acid) and Acetonitrile (50:50,
%v/v). Filtered through 0.45µm nylon membrane filter under vacuum filtration
and pumped at ambient temperature, at a flow rate of 1 mL/min with PDA
detection wavelength at 265nm. Injection volume was 10μL. The run time was
6 min and the retention time of Prazosin
and Polythiazide was found to be 2.989min and 2.134min respectively with
resolution of 5.1.
Chromatographic Parameters:
|
Equipment |
: |
Waters Alliance e2695 HPLC system with 2998 PDA detector |
|
Column |
: |
Symmetry C18 column (150mm×4.6mm, 5mm particle size) |
|
Flow rate |
: |
1mL/min |
|
Wavelength |
: |
265nm |
|
Injection volume |
: |
10 mL |
|
Column oven |
: |
Ambient |
|
Run time |
: |
6 Minutes |
Solutions
and sample preparation:
Preparation
of Ammonium acetate buffer:
A
0.01M Potassium dihydrogen orthophosphate buffer was prepared by dissolving
1.36 gm of Potassium dihydrogen orthophosphate in 1000mL of HPLC grade
water and pH was adjusted to 3.48 with orthophosphoric acid. The buffer was
filtered through 0.45μm nylon membrane filter to remove all fine particles
and gases.
Preparation
of mobile phase:
The above prepared Potassium dihydrogen orthophosphate
buffer and Acetonitrile HPLC grade were mixed in the proportion of 50:50, %v/v
and was filtered through 0.45μm nylon membrane filter and degassed by
sonication.
Preparation
of diluent:
Mobile
phase was used as diluent.
Preparation
of standard stock solutions of Prazosin
and Polythiazide:
Standard
stock solutions of Prazosin and
Polythiazide were prepared by dissolving 10mg of Prazosin and 2.5mg of Polythiazide in 10mL of
diluent into a 10mL clean dry volumetric flask and the standard solutions was
filtered through 0.45 μm nylon membrane filter
and degassed by sonicator to get the concentration of
1000µg/mL of Prazosin and
250µg/mL of Polythiazide.
Preparation
of standard solutions of Prazosin
and Polythiazide for assay:
From the above standard stock solution of 1000µg/mL of
Prazosin and 250µg/mL of Polythiazide further pipette 1mL
and transferred into a 10mL volumetric flask and dilute up to the mark with
diluent to get the concentration of 100µg/mL of Prazosin and 25µg/mL of Polythiazide.
Preparation of sample solutions of Prazosin and Polythiazide:
Twenty capsules were accurately weighed and capsule
powder equivalent to 2mg of Prazosin
and 0.5mg of Polythiazide were taken into 10mL clean dry volumetric
flask, diluent was added and sonicated to dissolve it completely and volume was
made up to the mark with the same diluent and filtered through 0.45 μm nylon membrane filter. Further pipette out 5mL from
the above Prazosin and Polythiazide sample
stock solution into a 10mL volumetric flask and diluted up to the mark with
diluent to get the concentration of 100µg/mL of Prazosin and 25µg/mL of Polythiazide. 10mL from standard and sample solution were injected into the
chromatographic system and the peak areas were measured for Prazosin and Polythiazide which was
shown in (Figure 3 and 4) and the % assay was calculated by comparing the peak
area of standard and sample chromatogram by using the formula given below and
the assay results was shown in (Table 1).
AT
WS DT
P
Avg. Wt
Assay
% = –––– x –––––x ––––x –––––x –––––––––––– X 100
AS
DS
WT 100 Label Claim
Where:
AT
= Average peak area of sample preparation
AS=
Average peak area of standard preparation
WS
= Weight of standard taken in mg
WT=Weight
of sample taken in mg
P =
Percentage purity of working standard
DS=
Dilution factor for standard preparation
DT=Dilution
factor for sample preparation
Table
1: Assay of marketed formulation of Prazosin and Polythiazide
|
Drug |
Minizide 432® capsule Label Claim (mg) |
Amount Found (mg) (n=6) |
% Label Claim ± % RSD (n=6) |
|
Prazosin |
2 |
2.006 |
100.28± 0.9 |
|
Polythiazide |
0.5 |
0.505 |
100.81± 1.0 |
RESULTS AND DISCUSSION:
Method Development:
To optimize the RP-HPLC
parameters, several mobile phase compositions were tried. A satisfactory
separation and good peak symmetry for Prazosin
and Polythiazide were obtained with a mobile phase containing a mixture
of 0.01M Potassium dihydrogen orthophosphate buffer (pH adjusted to 3.48 with
orthophosphoric acid) and Acetonitrile (50:50, %v/v) was delivered at a flow
rate of 1mL/min to get better reproducibility and repeatability. Quantification
was achieved with PDA detection at 265nm based on peak area. The retention time
of Prazosin and Polythiazide was
found to be 2.989min and 2.134min respectively with resolution of 5.1.
Linearity was established for Prazosin
and Polythiazide in the range of 25-150µg/mL for Prazosin and 6.25-37.5µg/mL for Polythiazide
with correlation coefficients (r2=0.999) and the percentage
recoveries for Prazosin are 100.34% and
Polythiazide is 100.32% respectively, which indicate
accuracy of the proposed method. The % RSD values of accuracy for Prazosin and Polythiazide were
found to be < 2 %. The % RSD values of method precision are 0.9% and 1% for Prazosin and Polythiazide respectively
and % RSD values of system precision are 1% and 0.9% for Prazosin and Polythiazide respectively.
The % RSD values of intermediate precision are 0.8% and 1.4% for Prazosin and Polythiazide respectively,
reveal that the proposed method is precise. LOD values for Prazosin and Polythiazide were
found to be 0.491µg/mL and 0.03µg/mL respectively and LOQ values for Prazosin and Polythiazide were found
to be 1.487µg/mL and 0.1µg/mL respectively. The % RSD values of robustness
studies were found to be < 2% reveal that the method is robust enough. These
data show that the proposed method is specific and sensitive for
the determination of Prazosin and
Polythiazide.
Method validation:
The
developed method for the simultaneous estimation of Prazosin and Polythiazide was validated as per the ICH
guidelines for the parameters like system suitability, specificity, linearity,
accuracy, precision, ruggedness, robustness, limit of detection (LOD) and limit
of quantitation (LOQ) 26.
System
suitability test:
At first the HPLC system was optimized as per the
chromatographic conditions. One blank followed by six replicates of a single
calibration standard solution of 100µg/mL of Prazosin and 25µg/mL of Polythiazide was injected to
check the system suitability. To ascertain the system suitability for the
proposed method, the parameters such as retention time, theoretical plates,
peak asymmetry and resolution were taken and results were presented in (Table
2).
Table
2: System suitability parameters for Prazosin and Polythiazide
|
Parameter (n=6) |
Prazosin |
Polythiazide |
|
Retention Time (Mins) |
2.989 |
2.134 |
|
Theoretical plates |
8536 |
4920 |
|
Tailing factor |
1.34 |
1.09 |
|
Resolution |
|
5.1 |
Specificity:
The effect of excipients and other additives usually
present in the combined capsule dosage form of Prazosin and Polythiazide in the determination under
optimum conditions was investigated. The specificity of the RP-HPLC method was
established by injecting the blank and placebo solution into the HPLC system.
The representative chromatogram of blank and placebo was shown in (Figure 5 and
6).
Linearity and range for Prazosin and Polythiazide:
Aliquots
of 0.25, 0.5, 0.75, 1, 1.25 and 1.5mL of mixed standard working solutions of Prazosin and Polythiazide was
pipetted out from the standard stock solution of 1000µg/mL of Prazosin and 250µg/mL of Polythiazide and transferred into a
series of 10mL clean dry volumetric flask and make volume up to the mark with
the same diluent to get the concentration of 25, 50, 75, 100, 125 and 150µg/mL
of Prazosin and 6.25, 12.5,
18.75, 25, 31.25 and 37.5µg/mL of Polythiazide.
The
calibration standard solutions of Prazosin
and Polythiazide were injected using a 10μL Hamilton Rheodyne injector and the chromatograms were recorded at
265nm and a calibration graph was obtained by plotting peak area versus
concentration of Prazosin and
Polythiazide respectively.
Table
3: Linearity for Prazosin and Polythiazide
|
Linearity of Prazosin |
Linearity of Polythiazide |
||
|
Concentration (µg/mL) |
Peak Area |
Concentration (µg/mL) |
Peak Area |
|
25 |
558377 |
6.25 |
37175 |
|
50 |
1092727 |
12.5 |
76265 |
|
75 |
1637102 |
18.75 |
118682 |
|
100 |
2174094 |
25 |
155120 |
|
125 |
2663563 |
31.25 |
195593 |
|
150 |
3222041 |
37.5 |
227639 |
The linearity data is presented in (Figure 7 and 8)
and (Table 3). Acceptance Criteria: Correlation coefficient should be
not less than 0.999.
Accuracy studies for Prazosin and Polythiazide:
The
accuracy of the method was determined by calculating recovery of Prazosin and Polythiazide by the
method of standard addition. Known amount of standard solution of Prazosin and Polythiazide at 50%, 100%
and 150% was added to a pre quantified sample solution and injected into the
HPLC system. The mean percentage recovery of Prazosin and Polythiazide at each level was calculated
and the results were presented in (Table 4 and 5). Acceptance Criteria:
The % Recovery for each level should be between 98.0 to 102.0%.
Table
4: Accuracy for Prazosin
|
% Level |
Amount Spiked (μg/mL) |
Amount recovered (μg/mL) |
% Recovery |
Mean % Recovery |
|
50% |
50 |
49.92 |
99.84 |
100.34% |
|
50 |
50.40 |
100.79 |
||
|
50 |
49.74 |
99.47 |
||
|
100% |
100 |
101.59 |
101.59 |
|
|
100 |
101.03 |
101.03 |
||
|
100 |
99.58 |
99.58 |
||
|
150% |
150 |
150.01 |
100.01 |
|
|
150 |
151.53 |
101.02 |
||
|
150 |
149.56 |
99.71 |
Table
5: Accuracy for Polythiazide
|
% Level |
Amount Spiked (μg/mL) |
Amount recovered (μg/mL) |
% Recovery |
Mean % Recovery |
|
50% |
12.5 |
12.56 |
100.51 |
100.32% |
|
12.5 |
12.41 |
99.27 |
||
|
12.5 |
12.37 |
98.93 |
||
|
100% |
25 |
25.35 |
101.40 |
|
|
25 |
25.30 |
101.21 |
||
|
25 |
25.31 |
101.23 |
||
|
150% |
37.5 |
37.81 |
100.81 |
|
|
37.5 |
37.56 |
100.17 |
||
|
37.5 |
37.27 |
99.37 |
Table
6: Method precision for Prazosin and
Polythiazide
|
S. No |
Peak Area of Polythiazide |
Peak Area of Prazosin |
|
1 |
154264 |
2170407 |
|
2 |
155055 |
2192630 |
|
3 |
156271 |
2149939 |
|
4 |
156341 |
2179888 |
|
5 |
158783 |
2201761 |
|
6 |
157427 |
2156488 |
|
Mean |
156357 |
2175186 |
|
Std. Dev. |
1619.5 |
20211.4 |
|
%RSD |
1.0 |
0.9 |
Precision
studies for Prazosin and Polythiazide:
Method precision (Repeatability):
From the above standard stock solution of 1000µg/mL of
Prazosin and 250µg/mL of Polythiazide further pipette 1mL
and transferred into a 10mL volumetric flask and dilute up to the mark with
diluent to get the concentration of 100µg/mL of Prazosin and 25µg/mL of Polythiazide was injected and analysed six times and was checked whether the method is
giving consistent results. The % RSD for the assay of six replicate injections
was calculated as mentioned in (Table 6). Acceptance Criteria: The % RSD for
the assay of six sample injections should not be more than 2%.
Table
7: System precision for Prazosin and
Polythiazide
|
S. No |
Peak Area of Polythiazide |
Peak Area of Prazosin |
|
1. |
154043 |
2158865 |
|
2. |
153626 |
2203077 |
|
3. |
156549 |
2141344 |
|
4. |
153705 |
2172404 |
|
5. |
156605 |
2168016 |
|
6. |
155116 |
2158118 |
|
Mean |
154941 |
2166971 |
|
S.D |
1374.7 |
20664.4 |
|
%RSD |
0.9 |
1.0 |
System precision:
The system precision was carried out to ensure that
the analytical system is working properly. The standard preparation
concentration of 100µg/mL of Prazosin
and 25µg/mL of Polythiazide was injected six times into the HPLC system
and the %RSD for the area of six replicate injections was calculated as
mentioned in (Table 7). Acceptance Criteria: The %RSD for the peak area
of six standard injections should not be more than 2%.
Intermediate precision/ruggedness:
The intermediate precision (also known as Ruggedness)
of the method was evaluated by performing precision on different laboratories
by different analysts and different days. The sample preparation concentration
of 100µg/mL of Prazosin and
25µg/mL of Polythiazide was injected six times into the HPLC system and the
%RSD for the assay of six replicate injections was calculated as mentioned in
(Table 8). Acceptance Criteria: The % RSD for the assay of six sample
injections should not be more than 2%.
Table
8: Intermediate precision for Prazosin
and Polythiazide
|
S. No |
Peak Area of Polythiazide |
Peak Area of Prazosin |
|
1. |
144700 |
1992746 |
|
2. |
147333 |
2026970 |
|
3. |
145375 |
2011318 |
|
4. |
149619 |
1994322 |
|
5. |
144200 |
2031773 |
|
6. |
145937 |
2000397 |
|
Mean |
146194 |
2009588 |
|
S.D |
1998.6 |
16724.1 |
|
%RSD |
1.4 |
0.8 |
Limit
of Detection (LOD) and Limit of Quantification (LOQ):
Limit of Detection (LOD) and Limit of Quantification (LOQ)
were calculated as 3.3×SD/S and 10×SD/S respectively as per ICH guidelines, Where
SD is the standard deviation of the response (Y-intercept) and S is the slope
of the calibration curve. The LOD is the smallest concentration of the analyte
that gives a measurable response (signal to noise ratio of 3). The LOD of Prazosin and Polythiazide was
calculated and shown in (Table 9). The LOQ is the smallest concentration of the
analyte which gives response that can be accurately quantified (signal to noise
ratio of 10). The LOQ of Prazosin
and Polythiazide was calculated and shown in (Table 9).
Table
9: LOD and LOQ for Prazosin and
Polythiazide
|
Drug |
LOD(μg/mL) |
LOQ(μg/mL) |
|
Polythiazide |
0.03 |
0.1 |
|
Prazosin |
0.491 |
1.487 |
Robustness:
As
part of the Robustness, deliberate change in the flow rate, mobile phase
proportion and temperature of ±10% was made to evaluate the impact on the
method. The results reveal that the method is robust. The results are
summarized in (Table 10).
Table
10: Robustness for Prazosin and
Polythiazide
|
S. No |
Condition |
% RSD of Polythiazide |
%RSD of Prazosin |
|
1. |
Flow rate (-) 0.9mL/min |
1.2 |
0.8 |
|
2. |
Flow rate (+) 1.1mL/min |
0.9 |
1.3 |
|
3. |
Mobile phase (-) 55B:45A |
0.8 |
0.6 |
|
4. |
Mobile phase (+) 45B:55A |
0.7 |
0.8 |
|
5. |
Temperature (-) 25°C |
0.7 |
0.8 |
|
6. |
Temperature (+) 35°C |
1.1 |
0.4 |
Stability
of solution:
The results of the solution stability experiments confirm
that the sample solutions and mobile phase used during the assays were stable upto 24hours at room temperature was calculated and shown
in (Table 11).
Table
11: Solution stability for Prazosin and
Polythiazide
|
|
|
Solution stability for Polythiazide |
||||
|
S. No. |
Time in hours |
Concentration(μg/mL) |
Retention time (min) |
Peak Area |
USP Plate Count |
Asymmetry |
|
1. |
0 |
25 |
2.197 |
224740 |
2233 |
0.9 |
|
2. |
24 |
25 |
2.124 |
144700 |
4550 |
1.24 |
|
Solution stability for Prazosin |
||||||
|
S. No. |
Time in hours |
Concentration (μg/mL) |
Retention time (min) |
Peak Area |
USP Plate Count |
Asymmetry |
|
1. |
0 |
100 |
2.988 |
1775994 |
8732 |
1.3 |
|
2. |
24 |
100 |
2.991 |
1992746 |
8268 |
1.35 |
Forced degradation studies:
Acid Degradation Studies:
To 1mL of stock solution of Prazosin and Polythiazide, 1mL of 2N Hydrochloric acid
was added and refluxed for 30mins at 600C. The resultant solution
was diluted to obtain 100µg/mL of Prazosin
and 25µg/mL of Polythiazide solution and 10µL solutions were injected
into the HPLC system and the chromatogram were recorded to assess the stability
of sample was shown in (Figure 9).
Alkali Degradation Studies:
To 1mL of stock solution of Prazosin and Polythiazide, 1 mL of 2N sodium hydroxide
was added and refluxed for 30mins at 600C.The resultant solution was
diluted to obtain 100µg/mL of Prazosin
and 25µg/mL of Polythiazide solution and 10µL solutions were injected
into the HPLC system and the chromatogram were recorded to assess the stability
of sample was shown in (Figure 10).
Oxidative degradation Studies:
To 1mL of stock solution of Prazosin and Polythiazide,
1 mL of 20% Hydrogen peroxide (H2O2) was added and the
solution was kept for 30mins at 60°C. For HPLC study,
the resultant solution was diluted to obtain 100µg/mL of Prazosin and 25µg/mL of
Polythiazide solution and 10µL solutions were injected into the HPLC system and
the chromatogram were recorded to assess the stability of sample was shown in
(Figure 11).
Thermal Degradation Studies:
The
standard drug solution was placed in oven at 1050C for 6hrs to study
dry heat degradation. For HPLC study, the resultant solution was diluted to
100µg/mL of Prazosin and
25µg/mL of Polythiazide solution and 10µL solutions were injected into the HPLC
system and the chromatogram were recorded to assess the stability of sample was
shown in (Figure 12).
Photolytic degradation studies:
The photochemical stability of the drug was also
studied by exposing the drug solution to UV light by keeping the beaker in UV
Chamber for 7days or 200 Watt hours/m2 in
photo stability chamber. For HPLC study, the resultant solution was
diluted to obtain 100µg/mL of Prazosin
and 25µg/mL of Polythiazide solution and 10µL solutions were injected
into the HPLC system and the chromatogram were recorded to assess the stability
of sample was shown in (Figure 13).
Water Degradation Studies:
Stress testing under neutral conditions was studied by
refluxing the drug in water for 6hrs at a temperature of 60ºC. For HPLC study,
the resultant solution was diluted to 100µg/mL of Prazosin and 25µg/mL of Polythiazide solution and 10µL
solutions were injected into the HPLC system and the chromatogram were recorded
to assess the stability of sample was shown in (Figure 14).
Table
12: Forced degradation data of Prazosin and Polythiazide in different
degradation conditions
|
Type of degradation |
Polythiazide |
Prazosin |
||||
|
Peak Area |
%Recovered |
% Degraded |
Peak Area |
%Recovered |
% Degraded |
|
|
Acid |
143068 |
92.24 |
7.76 |
2065482 |
95.22 |
4.78 |
|
Base |
148136 |
95.51 |
4.49 |
2103021 |
96.95 |
3.05 |
|
Oxidative |
150073 |
96.76 |
3.24 |
2115736 |
97.54 |
2.46 |
|
Thermal |
150813 |
97.24 |
2.76 |
2117903 |
97.64 |
2.36 |
|
Photolytic |
152101 |
98.07 |
1.93 |
2139560 |
98.64 |
1.36 |
|
Water |
154402 |
99.55 |
0.45 |
2152613 |
99.24 |
0.76 |
CONCLUSION:
RP-HPLC method for
the simultaneous estimation of Prazosin
and Polythiazide in their combine dosage form was established and
validated as per the ICH guidelines. Linearity was achieved for Prazosin and Polythiazide in the
range of 25-150µg/mL for Prazosin and
6.25-37.5µg/mL for Polythiazide with correlation coefficients (r2=0.999).
The percentage recoveries of Prazosin
and Polythiazide were achieved in the range of 98-102% which was within
the acceptance criteria. The %RSD was NMT 2% which proved the precision of the
developed method. The developed method is simple, sensitive, rapid, linear,
precise, rugged, accurate, specific, and robust. The forced degradation studies
were performed by using HCl, NaOH, H2O2, thermal, UV
radiation and water. Prazosin and Polythiazide are
more sensitive towards acidic, basic and oxidative degradation condition which
was shown in (Table 12). No interference from any components of pharmaceutical
dosage form or degradation products was observed and the method has been
successfully used to perform long term and accelerated stability studies of Prazosin and Polythiazide formulations.
Hence it can be used for the routine analysis of Prazosin and Polythiazide in their bulk and combine
dosage form.
ACKNOWLEDGEMENT:
The authors are thankful
to CMR College of Pharmacy, Kandlakoya, Medchal, Hyderabad, Telangana, India for
providing the chemicals and instruments and Synthokem
Labs Private Ltd., Hyderabad, India for providing the drug samples for
research.
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Received on 05.08.2019
Modified on 28.09.2019
Accepted on 19.11.2019
© RJPT All right reserved
Research J. Pharm. and Tech.
2020; 13(4):1779-1787.
DOI: 10.5958/0974-360X.2020.00321.2