Simultaneous determination of phosphodiesterase-5 (PDE-5) inhibitors and their analogues in sexual enhancement products / Nur Baizura Bujang
Adulteration of herbal health supplements (HHSs) with phosphodiesterase-5 (PDE-5) inhibitors and their analogues is becoming a worldwide problem. These HHSs are marketed for increasing sexual performance, in men. In legal medical practice, PDE-5 inhibitors are only used to treat patients with ere...
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| Format: | Thesis |
| Published: |
2018
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| Online Access: | http://studentsrepo.um.edu.my/11490/4/baizura.pdf http://studentsrepo.um.edu.my/11490/ |
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| Summary: | Adulteration of herbal health supplements (HHSs) with phosphodiesterase-5 (PDE-5)
inhibitors and their analogues is becoming a worldwide problem. These HHSs are
marketed for increasing sexual performance, in men. In legal medical practice, PDE-5
inhibitors are only used to treat patients with erectile dysfunction (ED), but these
adulterated HHSs are also being utilised by men without ED for recreational purposes.
Screening the presence of these adulterants is important to protect the safety of
consumers. However, the complexity in managing this adulteration problem involve
many different aspects including the ever increasing number of new analogues, the
budget restriction in obtaining the reference standards for these analogues and the
method needed to simultaneously detect all PDE-5 inhibitors and their analogues.
In order to develop the capability to produce in-house standards, ten sildenafil
analogues were synthesised. The purity of the synthesised standards was above 90%.
These synthesised standards together with fifty-one commercial reference standards of
PDE-5 inhibitors and their analogues were then used to build a LCMS spectral library.
A LCMS IT-TOF method was developed and validated for simultaneous determination
of the sixty-one standards.
The determination method was applied to investigate adulterated HHSs sold in the
Malaysian market. Sixty-two products that claim to enhance men’s sexual health were
sampled between April 2014 and April 2016. These products included unregistered
products seized by the Pharmacy Enforcement Division of the Ministry of Health (n =
39), products sent to the National Pharmaceutical Regulatory Agency for preregistration testing (n = 9) and products investigated under the post-registration market
surveillance programme (n = 14). The products were tested against the in-house spectral
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library consisting of 61 PDE-5 inhibitors and analogues using the validated LCMS ITTOF method. Thirty-two (82%) of the unregistered products and two (14%) of the
registered products were found to be adulterated with at least one PDE-5 inhibitor or
analogue, while none of the pre-registration products contained the adulterants of our
interest. A total of 16 different adulterants were detected and 36% of the adulterated
products contained a mixture of two or more adulterants. Two of the adulterants, which
were not included in the spectral library, were identified as acetil acid and xanthoantrafil
using the formula predictor software included in the LCMS IT-TOF system. In
conclusion, this study has demonstrated that the adulteration of unregistered herbal
products in the Malaysian market is an alarming issue that needs to be urgently
addressed by the relevant authorities. |
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