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Prelox
®
for Improvement of Erectile Quality
average score of 15±7, which increased to 19±3 at trial end. The The pharmacokinetics and excretion of Pycnogenol were shown to be
improved erectile quality in the Prelox group was statistically of complicated nature in humans. The smaller flavonoid constituents,
significant compared with the placebo group (p<0.05) (see Figure 2). namely the phenolic acids and catechin, are found in blood plasma of
More men in the Prelox group than in the control group reported humans within 30 minutes after oral consumption.
22
These constituents
increased morning erections (36 versus 12%), easier to initiate erections are excreted in the urine as sulphates and glucuronates, with peak
(38 versus 12%), partner noticing increased interest (38 versus 6%) and times about two hours post-consumption.
23
The procyanidins are
partner noticing improved performance (38 versus 12%). Many men metabolised in the colon prior to absorption into the blood stream.
were uneasy about responding to the above questions. Specifically, the metabolite δ-(3,4-diydroxy-phenyl)-γ-valerolactone was
identified in the plasma beginning four hours after consumption, and
Blood chemistry and rheology found no major changes after six months appears in the urine at peak eight to 10 hours post-consumption.
of Prelox or placebo intake. A non-significant decrease of systolic blood Several further metabolites can be found in the plasma of humans that
pressure from a baseline average of 138.9 to 131.0mmHg was found in have so far not been identified in the urine.
the Prelox group. A statistically significant increase of plasma
testosterone was evident in the Prelox group, from a baseline of 458 to Adverse Effects
544ng/dl after six months, representing an increase of 18.8%. In all four clinical trials Prelox was well tolerated and no side effects
occurred. Prelox has been marketed in the US and in European
Duration of Action countries since 2004. Post-marketing surveys have resulted in a
In principle, the activity of Prelox is directed towards restoring collection of consumer self-reported side effects directly to the
endothelial function, which will allow men to spontaneously respond to corresponding marketing companies. The following unwanted effects
sexual arousal. How quickly a man experiences an improvement of were self-reported: dizziness (n=2), nausea (n=1), vertigo (n=1),
erectile quality will depend on his individual situation. From the clinical headache (n=1), diarrhoea (n=1), worsened tinnitus symptoms (n=1),
trial of Stanislavov et al., information is available on the earliest effects feeling sick (n=1) and hypotension (n=1). In all cases it was advised
of erectile quality.
14
This was reported to be as early as one day after to immediately discontinue the supplementation. It was not possible
taking four Prelox tablets, with the latest response reportedly after nine in these cases to verify the nature and circumstances of the
days; the mean response occurred after 4.9 days. This trial also showed self-reported side effects. Likely only a small percentage of men will
that following discontinuation of Prelox for one month, erectile quality report their side effects to the manufacturer or the website
decreases to almost pre-treatment levels. (www.Prelox.com). However, in view of the considerable quantities of
Prelox sold during the past five years, the number of unwanted side
An important point to consider is whether a habituation effect may effects appears to be fairly low and is in concordance with the
occur after continuous supplementation with Prelox, with the effect on experience from clinical trials.
erectile quality gradually fading with time. The study by Ledda et al.
provides information that this does not occur; in fact, the contrary is Safety and Drug Interactions
true.
21
A comparison of IIEF scores after three months on Prelox with Pycnogenol acute oral toxicity is very low, with a demonstrated no
scores after six months clearly shows that erectile quality further observed adverse effect level (NOAEL) of 150mg/kg.
9
Pycnogenol
improves following an additional three months of treatment. Therefore, itself is known to cause stomach discomfort in some particularly
in order to achieve the best effects Prelox would need to be taken sensitive people because of the pronounced astringency of the
continuously, without interruption. procyanidins. This happens only when Pycnogenol is taken on an
empty stomach. Interestingly, stomach discomfort has not been
Dosing and Absorption reported for Prelox. A possible explanation is that the considerable
In all clinical investigations for improvement of erectile quality, a daily amount of amino acids helps to avoid the stomach discomfort.
dosage of four Prelox tablets was taken. In one study the equivalent of
six Prelox tablets was taken for one month. The ideal initial dosage There is some dispute as to possible harm from L-arginine in people
would thus be four Prelox tablets a day: two in the morning after suffering from herpes. As early as the 1960s it was found that
breakfast and another two after dinner. Once erectile quality has L-arginine promotes replication of herpes simplex in tissue culture,
sufficiently improved, the dosage may be adjusted to a maintenance while L-lysin inhibits replication. The authors concluded: “the in vitro
dosage, which could be three or two Prelox tablets a day. The suitable data may be the basis for the observation that patients prone to
maintenance dose will depend on a man’s individual condition. herpetic lesions and other related viral infections, particularly during
periods of stress, should abstain from arginine excess and may also
Metabolism and Excretion require supplemental lysine in their diet”.
24
Whereas L-lysin indeed
Dietary L-arginine is absorbed in the small intestine via a specific amino appears to offer prophylactic activity for managing recurrent herpes
acid transport system. About 60% of the absorbed L-arginine is outbreaks in humans,
25
more recent studies suggest that L-arginine
metabolised by gastrointestinal enterocytes, while only 40% reaches the has antiviral effects against herpes simplex.
26
systemic circulation intact.
5
The average dietary consumption of
L-arginine is about 5g/day. L-arginine undergoes various metabolic fates: A further unsubstantiated possible side effect of L-arginine is the
much is converted to NO and L-citrulline, the latter being largely promotion of tumour growth. One group has described higher
converted in the proximal renal tubule to L-arginine. Furthermore, protein synthesis in breast tumours as a result of supplementation
L-arginine may be utilised for protein synthesis or converted into other with L-arginine.
27
The same group later argued that dietary
amino acids such L-ornithine, L-proline and L-glutamate. L-arginine is an supplementation with L-arginine would offer adjuvant treatment for
alkaline amino acid that is not very water-soluble, unless in ionic forms improved host defence in breast cancer patients as a result of
with anionic countercharge; aspartate fulfils this purpose in Prelox. immunostimulatory effects.
28
The work of this group has left
EUROPEAN ENDOCRINOLOGY 73
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