10337_2009_954_article 1.5
LC Determination of Isosorbide-5-Mononitrate in Human Plasma
Himanshu S. Karmalkar
&, Mohan M. Metku, Milind S. Bagul, Asmita C. Nimkar, Rajen D. Shah
Raptim Research Limited, A-226, TTC Industrial Area, Mahape, Navi Mumbai, Maharashtra 400701, India; E-Mail:
[email protected]
Received: 3 June 2008 / Revised: 23 November 2008 / Accepted: 15 December 2008
LC-MS–MS [–] and GC–MS []However, no LC–UV method has been
developed for the determination ofISMN from human plasma.
A simple, sensitive, selective and cost effective LC–UV method was developed for determi-
GC-ECD is the most widely used
nation of isosorbide mononitrate in human plasma using guaifenesin as an internal standard.
instrumental method due to its high
Isosorbide mononitrate in plasma was extracted by a single step liquid extraction using tert-
sensitivity and selectivity. However, it
butyl methyl ether and chromatographed on a C18 column using water and acetonitrile
was shown by Pastera et al. that
(80:20 v/v) as mobile phase. The method was validated and exhibited a linear range from
ISMN had a substantial decomposition
51.6 to 2064.4 ng mL-1. The inter- and intra-assay accuracy ranged from 97.2–102.7 to
when the injector temperature was higher
94.2–105.5%, respectively, with precision less than 10% in both the cases. The LLQ was
than 150 °C. If the injector temperature
51.6 ng mL-1. The validated method was applied to the quantitation of isosorbide mononi-
was low, it promoted the condensation of
trate from plasma samples in a pharmacokinetic study.
non-volatile compounds causing con-tamination of injector system and a rapiddecrease in the sensitivity. Morrison et al.
[] used packed GC columns withoutmononitrate derivatisation.
SPE with ENVI 18 cartridges ] or
Column liquid chromatography
Extrelut columns ] replaced the labo-
rious liquid–liquid extraction in three
Isosorbide-5-mononitrate in human plasmaGuaifenesin
methods. Gremeau et al. ] obtained aLLQ of 20 ng mL-1. Pommier et al. []reported a method requiring a silylationpretreatment of glassware to preventadsorption of ISMN to the glass. Jain
longer elimination half-life, no first-pass
et al. [quantified ISMN via stable
metabolism and no metabolites, leading
acetate adduct formation using LC-ESI-
to more predictable and reproducible
MS–MS to give a LLQ of 10 ng mL-1.
clinical effect
The salient features of their method were
[3.3.0] octan-4-ol is an active metabolite
The analytical techniques developed
low sample volume and SPE with direct
of isosorbide dinitrate. ISMN is a long
in recent years for the quantitation of
injection of eluent and short run time.
acting organic nitrate vasodilator used in
ISMN from human plasma include LC
The method described here was
the treatment of angina pectoris. It has
with a Thermal Energy Analysis detector
developed with the aim of obtaining a
[], capillary GC with an electron-
compound isosorbide dinitrate, such as
effective LC–UV analysis with a short
Full Short CommunicationDOI: 10.1365/s10337-009-0954-x
Ó 2009 Vieweg+Teubner GWV Fachverlage GmbH
run time for the determination of ISMN
EZChrome Elite software (version-3.2.1)
was 22%. Interference from plasma at
in human plasma. tert-Butyl methyl
was used for data handling. Analysis was
the retention time of ISMN was ob-
ether as extraction solvent evaporates
performed on a 5 lm Merck Purosphere
served in samples extracted with diethyl
very quickly, allowing 100 samples to be
ether. tert-Butyl methyl ether was the
processed and analysed in a day. The
solvent which showed no interference at
extraction efficiencies of ISMN using
with water:acetonitrile (80:20 v/v) at
the retention time of ISMN and GF and
tert-butyl methyl ether in polypropylene
1 mL min-1. The column was main-
yielded an extraction efficiency of better
and glass tubes were found to be similar
tained at 20 °C. Detection was carried
than 50%. An appropriate internal
and consistent, indicating that there was
out at 220 nm.
standard can control extraction and LC
no loss by evaporation of nitrates or
injection variability. Although Guaifen-
sorption to glassware. ISMN is a very
esin is not chemically and structurally
Preparation of Stock
related to the analyte, it was chosen as
hence our method is not as sensitive as
and Working Solutions
an internal standard for its stability in
other reported methods. Although the
prepared solutions and a good response
LLQ value of 51.6 ng mL-1 established
Primary stock solutions of ISMN and
at the detection wavelength. Its selection
in our method was higher it is regarded
GF were separately prepared by dissolv-
was also based on its good chromato-
as acceptable. The method was success-
ing an appropriate amount in methanol
graphic and extraction behavior.
to yield a concentration of 1 mg mL-1 of
pharmacokinetics of ISMN after oral
each. The standard working solutions
administration of 60 mg sustained re-
were obtained by further dilution of the
Sample Preparation
lease (SR) tablets to healthy volunteers.
stock solutions with mobile phase. TheGF working solution had a concentra-
Calibration standard samples and qual-
tion of 25 lg mL-1. All solutions were
ity control samples were extracted by
stored at 2–8 °C and equilibrated to
using liquid–liquid extraction. To each
room temperature before use.
polypropylene vial containing 0.5 mL
Chemicals and Reagents
sample, 50 lL of IS was added at aconcentration of 25 lg mL-1 and also3.0 mL of tert-butyl methyl ether, which
All chemicals and reagents used in the
Preparation of Calibration
were then vigorously vortex-mixed for
study were LC grade. Acetonitrile and
Standards and Quality Control
3 min followed by centrifuging at 4,500g
tert-butyl methyl ether were purchased
at 4 °C for 5 min. The organic phase was
from Merck (Mumbai, India). Water
transferred to a new polypropylene vial
used in the mobile phase was deionised
Calibration standards were prepared at
and evaporated to dryness in a water
and purified by a Milli-Q water purifi-
8 different concentrations of 51.6, 103.3,
bath at 40 °C under a stream of nitrogen
cation system from Millipore (Bedford,
206.6, 413.1, 826.2, 1238.6, 1651.5 and
gas. The dried residue was reconstituted
MA, USA). A working standard of
2064.4 ng mL-1 of ISMN in plasma.
with 100 lL of mobile phase and vortex-
ISMN was obtained from Pan Drugs
Quality control (QC) samples were pre-
mixed briefly. A 50 lL aliquot was in-
(Gujarat, India), and guaifenesin (GF)
pared at three different concentrations
jected into the LC system.
which was used as an internal standard
of low QC (LQC-151.7), medium QC
was obtained from Unique Pharmaceu-
tical Labs. (Thane, India). Drug free
1816.7) ng mL-1. All of these samples
Method Validation
human CPDA (citrate phosphate dex-
were prepared by spiking appropriate
trose adenine) plasma bags (six different
amounts of standard stock solutions into
The method validation was carried out
lots) were obtained from JVP Blood
the drug free plasma samples. They were
according to the US Food and Drug
Bank (Vashi, Navi Mumbai, India).
stored at -20 °C.
validation guidance [].
The specificity of the method was
Method Development
tested by screening six different batches
of drug free human plasma. Each blank
Dichloromethane, diethyl ether, n-hex-
sample was tested for interferences at the
The LC instrument was an Agilent
ane, tert-butyl methyl ether and their
retention time of ISMN and GF using
1200 series LC (Waldbronn, Germany)
mixtures with each other were tried for
the proposed extraction procedure. Fre-
the extraction of ISMN and GF. With
quently used over-the-counter medicines
such as acetaminophen, ibuprofen, dic-
Peltier cooler (G1330B), thermostatted
ciency of the analyte was 12%. With a
lofenac and cetirizine were also injected
column compartment (G1316A) and a
mixture of dichloromethane and n-hex-
to check for interference at the retention
variable wavelength detector (G1314B).
ane (1:1 v/v) the recovery of the analyte
time of the analyte and GF. For sensi-
Full Short Communication
tivity determination, six samples at LLQ
concentration (51.6 ng mL-1) of ISMN
were investigated and the reproducibilityand precision were determined.
Linearity was tested for the concen-
tration range of 51.6–2064.4 ng mL-1.
For the determination of linearity, ablank sample, a zero sample (blank+ IS) and eight calibration standards
were used. Samples were quantifiedusing the ratio of peak area of analyte to
that of the IS. A weighted linear regres-
sion (1/concentration) was performed
with nominal concentrations of calibra-
tion levels. Peak area ratio was plottedagainst
standard curves were calculated.
The intra-day precision and accuracy
of the assay were measured by analyzing
six spiked samples of ISMN at each QC
level (151.7, 908.3 and 1816.7 ng mL-1).
The inter-day precision and accuracy
was determined over 3 days by analyzing30 QC samples (n = 6 for each concen-
tration level) each day.
The validation was carried out using
Fig. 1. Representative chromatograms of ISMN (1) and guaifenesin (2) in human plasma.
human plasma which contained CPDA
A Blank human plasma; B blank plasma spiked with ISMN and IS at LQC level; C plasma
as anticoagulant. Normally EDTA is
sample from a subject 4 h after oral administration of 60 mg sustained release (SR) isosorbide-5-
used as an anticoagulant and it was
mononitrate formulation
therefore necessary to assess the antico-agulant effect and understand its impacton the quantitation of ISMN from aplasma matrix. A significant anticoagu-
ples were kept in the autosampler at 7 °C
respectively. The total analysis time was
lant effect would prevent using EDTA as
for 24 h and then injected to determine
an anticoagulant. Anticoagulant effect
the autosampler stability The freeze–
No interfering peaks were observed at
was performed by comparing LQC and
the retention times of either the analyte or
HQC samples (n = 3) prepared in EDTA
-20 ± 5 °C), was studied after subject-
IS in six different batches of drug-free
anticoagulant-based human plasma and
ing the samples to three freeze–thaw
human plasma samples. A representative
cycles. For dry extract stability the dried
LC chromatogram of extracted blank
prepared in CPDA anticoagulant-based
extracts were kept at 2–8 °C for 24 h
plasma is shown in Fig. The precision
after which they were brought to ambi-
for the six plasma samples spiked with
Evaluation of stability of samples
ent temperature, reconstituted and then
ISMN at LLQ concentration was 5.9%
was based on the comparison of stored
analyzed. In order to determine the sta-
with accuracy ranging from 98.6 to
samples against freshly prepared samples
bility of ISMN in solution, the working
of the same concentration. The percent-
solution was kept at 2–8 °C for 6 days.
The method exhibited a good linear
age difference between the back calcu-
Thereafter, the mean areas of ISMN
response over the range of concentra-
lated concentrations obtained in the
from six replicate chromatographic runs
tion from 51.6 to 2064.4 ng mL-1. The
stored samples and freshly prepared
were compared to that of mean area of a
mean correlation coefficient was 0.998.
samples was evaluated. Four aliquots
freshly prepared solution of the same
The mean accuracy values of each cali-
each of LQC and HQC concentrations
bration standard were close to each
were used for the stability study. For
assessment of long term stability, the
samples were kept in deep freezer at
Results and Discussion
between 94.9 and 105.5% with a precision
-20 ± 5 °C for 30 days and thereafter
of 6.9–9.2%. The inter-day accuracy was
analyzed. Bench top stability was studied
Using the chromatographic conditions
between 97.2 and 102.7% with a precision
on samples kept at ambient temperature
described above, the peaks of ISMN and
of 5.4–9.9%. The results are presented in
(20–30 °C) for 8 h. The processed sam-
GF eluted at about 3 and 6 min,
Table A chromatogram of ISMN at the
Full Short Communication
Table 1. The intra- and inter-batch precision and accuracy of the method for the determination
found to be stable for 6 days at 2–8 °C
of ISMN in human plasma
with %RSD of 1.2%.
(mean ± SD, ng mL-1)
Pharmacokinetic Study
Figure shows the time course of the
ISMN plasma concentration of 21 heal-
thy human subjects who received 60 mg
sustained release ISMN tablets under
conducted strictly in accordance withguidelines laid down by the International
USFDA []. The pharmacokinetic data
are tabulated in Table
-1 Lm. 400
The developed and validated LC method
proved to be cost effective, simple, rapid,
selective and convenient for the deter-
mination of ISMN in human plasma.
The method has the advantages of goodselectivity,
procedure, high throughput and wide
linear range. It has been successfullyapplied to the pharmacokinetics of
Fig. 2. Time course of the plasma ISMN concentration in healthy subjects after a single 60 mg
ISMN in healthy volunteers after single
(SR) oral dose. Each point represents the mean ± SD (n = 21)
oral administration of 60 mg sustainedrelease formulation.
Table 2. Pharmacokinetic parameters of ISMN in 21 healthy subjects after a single 60 mgsustained release oral dose
1. O'Neil Maryadele J (ed) (2001) The
Merck index, 13th edn, monograph no.
5246, p 935 and monograph no. 4571,
p 812. Merck Research Laboratories,
Division of Merck, Whitehouse Station
2. Chasseaud LF (1987) Cardiology 74:6.
LQC concentration with an internal
2.7% for LQC and HQC, respectively,
3. Major RM, Taylor T, Chasseaud LF,
Darragh A, Lambe RF (1984) Clin
standard in shown in Fig.
for 8 h at ambient temperature with
Pharmacol Ther 35:653
The accuracy and precision obtained
percent difference of 8.0 and -4.5% for
4. Pastera J, Vyslouzil L, Kvetina J (2004) J
on LQC samples prepared using EDTA
LQC and HQC, respectively, for 24 h in
Chromatogr B Analyt Technol BiomedLife
plasma ranged from 98.6 to 102.0% with
the autosampler with percent difference
precision of 2.3 and 99.6% to 101.3%
of 12.4 and -1.0% for LQC and HQC,
5. Gremeau I, Sautou V, Pinon V, Rivault
with a precision of 1.0% on HQC sam-
respectively. The dried extract was stable
F, Chopineau J (1995) J Chromatogr B
ple indicating that there was no antico-
for 24 h at 2–8 °C with percent differ-
Analyt Technol Biomed Life Sci 665:399–403.
agulant effect and the biostudy samples
ence of 2.6 and -1.8% for LQC and
6. Michel G, Fay L, Prost M (1989) J
could be collected using EDTA as an
HQC, respectively and ISMN in plasma
Chromatogr A 493:188–195
was stable for three freeze–thaw cycles
7. Santoni Y, Rolland PH, Cano J-P (1984)
J Chromatogr A 306:165–172
ISMN was found to be stable in the
with percent difference of 9.2 and
plasma matrix for 30 days at -20 °C
-13.6% for LQC and HQC, respec-
Chromatogr A 308:153–164.
(LTS) with percent differences of 4.6 and
tively. The stock solution of ISMN was
Full Short Communication
9. Maddock J, Lewis PA, Woodward A,
Massey PR, Kennedy S (1983) J Chro-
Chabard JL, Beyssac E, Aiache JM,
matogr A 272:129–136
14. Jain DS, Subbaiah G, Sanyal M, Shriva-
Nadesclaire M (1995) J Chromatogr B
10. Marzo A, Treffner E (1985) J Chroma-
stav PS, Pal U, Ghataliya S, Kakad A,
Analyt Technol Biomed Life Sci 663:153–
togr A 345:390–395. doi:
Bhatt J, Munjal V, Patel H, Shah S (2006)
Rapid Commun Mass Spectrom 20(19):
11. Pennings JM, De Haas JM (1995) J
2921–2931. doi:
Method Validation, Center for Drug
Chromatogr B Analyt Technol Biomed
15. Silva LC, Oliveira LSOB, Mendes GD,
Evaluation and Research (CDER), May
Life Sci 675:332–336
Garcia G, Pereira ADS, Nucci GD (2006)
12. Sioufi A, Pommier F (1984) J Chroma-
J Chromatogr B Analyt Technol Biomed
19. Guidance for Industry, E6 Good Clinical
togr A 305:95–103
Practice: Consolidated Guidance, Center
13. Pommier F, Gauducheau N, Pineau V,
Sioufi A, Godbillon J (1996) J Chroma-
16. Sun X, Li X, Cai S, Qin F, Lu X, Li F
(CDER), April 1996
togr B Analyt Technol Biomed Life Sci
(2007) J Chromatogr B 846:323–328
Full Short Communication
Source: http://www.raptimresearch.com/Pdf/Determination-of-Isosorbide-Mononitrate.pdf
ADVOCATING FOR THE RIGHT TO INFORMATION – THE SWEDISH "ODDITY"? By David Goldberg Co-convener, Campaign for Freedom of Information in Scotland December 2002 The history of freedom of information in practice in the world is extremely varied and complete --Thomas Blanton INTRODUCTION: GENERAL ADVOCACY TIPS Using the Communication Initiative's site1 search engine a search for the term "advocacy" brings up 2537 matches. So, one could be forgiven for not doing justice to the complexity of the concept in a short paper. However, quoting a couple of stipulative, working definitions might be helpful. Firstly, the USA-based Advocacy Institute states that,
MAZAGON DOCK LIMITED (A Government of India Undertaking) Dockyard Road, Mazagon, Mumbai 400 010. INDIA Tel. No.: 022 - 2376 3252 Fax No. : (022) 2373 8151 Website: www.mazagondock.gov.in Email: [email protected] [email protected] TENDER ENQUIRY IN SINGLE BID SYSTEM FOR SUPPLY OF MEDICINES ON ANNUAL RATE CONTRACT BASIS