A Sensitive and Simple High Performance Liquid Chromatographic Method for Quantification of Tadalafil in Human Serum Bioequivalence and Quality Control Laboratory, Faculty of Pharmacy, Saint-Joseph University,Mathaf, LebanonKEY WORDS: HPLC, tadalafil, assay,
centration range tested (10-800 ng/mL).
Accuracy, precision, and stability studieswere satisfactory. This analytical proce-
dure is relatively inexpensive and simple
paraben was used as the internal stan-dard. Optimum conditions for tadalafil
Tadalafil is a potent and selective phos-
single-step liquid–liquid extraction with
vasodilation of erectile tissues.1-3 Oral
less than 10 ng/mL for tadalafil. The cali-
The Journal of Applied Research • Vol. 6, No. 1, 2006
Table 1. Intraday Variability of the Assay for Tadalafil in Serum (4 series)
Concentration Concentration Standard Coefficient Added (ng/mL) Found (ng/mL) Deviation of Variation (%)
Correlation coefficients are 0.9984, 0.9984, 0.9984, and 0.9993 for each of the 4 curves.
Table 2. Interday Variability of the Assay for Tadalafil in Serum (5 series)
Concentration Concentration Standard Coefficient Added (ng/mL) Found (ng/ml) Deviation of Variation (%)
Correlation coefficients are 0.9993, 0.9993, 0.9991, 0.9993, and 0.9993 for each of the 5 curves
oral dosing has not been determined.
life of 17.5 hours in healthy subjects.5-7
Lebanon, and is described in this report.
be determined in biological samples,dietary supplements, or herbal matrices
EXPERIMENT Reagents and Standards
All chemicals used were reagent grade.
tion8-10 or micellar electrokinetic capil-
The Journal of Applied Research • Vol. 6, No. 2, 2006
Figure 1. Chromatograms of (A) standard tadalafil solution, (B) extracted sample at 800 ng/mL,
(C) blank serum, (D) blank serum with internal standard, and (E) extracted sample at 10 ng/mL.
Station, NJ). Tadalafil standard was sup-
water/acetonitrile (50/50, v/v). Internal
Vol. 6, No. 2, 2006 • The Journal of Applied Research
Table 3. Tadalafil Recovery After Extraction:
Tadalafil at Different Concentrations and
USA). The data were collected using thesystem software (Chemstation 1990-
Concentration Average Extraction Coefficient (%) (n=3 for each level) Chromatographic Conditions
5-µm particle size, 250 x 4 mm I.D., with
with glacial acetic acid (0.1 mM, pH 2.5-
UV detection was performed at 280 nm. All analyses were made at room temper-ature. The injection volume was 25 µL,
trile. All stock solutions were protected
through each sample before injection.
from light and kept at -20˚C. They werestable for at least 6 months. Serum Extraction Procedure
stock solution with drug-free serum.
Stability of the drug in serum at –20˚C
a micropipette while gently vortexingthe tubes. To each tube 6 cc of
Instrumentation Table 4. Drug-Free Human Serum Spiked With 3 Different Concentrations of Tadalafil and Stored at –20˚C Over a 6-Month Period Concentration Concentration Obtained (ng/mL) The Journal of Applied Research • Vol. 6, No. 2, 2006
dichloromethane extraction of serumsamples were not less than 75% over the
For assay validation, tadalafil was mixedwith drug-free human serum over the
stored at –20˚C did not show significant
ined using 4 series, and interday variabil-
performed on 5 separate days. Tables 1and 2 show the results of within-run and
DISCUSSION AND CONCLUSION
described in this report for the determi-
studied (correlation coefficients 0.998 to
ng/mL were not tested for linearity.
ric detection is not available. The assay
tetraacetic acid in the collection tube.
for determination of tadalafil concentra-
than 10 ng/mL showed CVs more than10% and were not incorporated in the
curves). The detection limit (3 x signal-
Pomerol JM, Rabasseda X. Tadalafil, a fur-
ther innovation in the treatment of sexual
dysfunction. Drugs Today (Barc). 2003;39:103-
grams of standard tadalafil solution,extracted sample at 800 ng/mL, blank
esterase-5 antagonists. Curr Urol Rep.
dard, and extracted sample at 10 ng/mL.
Seftel AD. Phosphodiesterase type 5 inhibitor
differentiation based on selectivity, pharma-
cokinetic, and efficacy profile. Clin Cardiol.Vol. 6, No. 2, 2006 • The Journal of Applied Research
Bella AJ, Brock GB. Tadalafil in the treat-
Gratz SR, Flurer CL, Wolnik KA. Analysis of
ment of erectile dysfunction. Curr Urol Rep.
undeclared synthetic phosphodiesterase-5-
inhibitors in dietary supplements and herbal
matrices by LC-ESI-MS and LC-UV. J Pharm
Gupta M, Kovar A, Meibohm B. The clinical
Biomed Anal. 2004;36:525-533.
inhibitors for erectile dysfunction. J Clin
10. Zhu X, Xiao S, Chen B, et al. Simultaneous
determination of sildenafil, vardenafil and
tadalafil as forbidden components in natural
dietary supplements for male sexual potency
treatment of erectile dysfunction. Expert
by high-performance liquid chromatography-
Opin Pharmacother. 2003;4:2049-2056.
electrospray ionization mass spectrometry. JChromatogr A. 2005;1066:89-95.
phosphodiesterase-5 inhibitors. Int J Clin
11. Rodriguez Flores J, Berzas Nevado JJ,
Development of a micellar electrokinetic cap-
et al. Quantification of tadalafil in human
illary chromatography method for the deter-
mass spectrometry with electrospray ioniza-
erectile dysfunction therapy. J Chromatogr B
tion. J Chromatogr B Analyt Technol BiomedThe Journal of Applied Research • Vol. 6, No. 2, 2006
From Scottish bagpipes to lively Celtic folk to at our local schools with his singer songwriter folk songs Japanese Shakuhachi ﬂ ute, the entertainment at this years’ Art in the Redwoods goes global. To kick it all oﬀ , long time coastal resident and radio producer/host DJ On Sunday be sure to check out Gualala Arts’ very Sister Yasmin will open both days’ musical extravaganza own
KANTONALER KRISENSTAB KKS Situationsbericht Influenza A/H1N1-Stamm im Kanton Basel-Landschaft Stand 29. April 2009, 0800 Uhr 1. Ausganglage Die WHO hat die Phase 4 von 6 ausgerufen. Phase 4 bedeutet: Ausbrüche mit beschränkter Mensch zu Mensch Übertragung und die Ausbreitung ist klar lokalisiert. Ziel ist es nun, Eradikation des Virus bzw. Verhinderung seiner Ausbreitung, um Z