By Travis DeGraff

Repros Therapeutics Inc

Repros Therapeutics is a pharmaceutical company interested in changing testosterone levels for all men needing some extra help.  Repros Therapeutics is developing the drug called Androxal.  Androxal is simply the single isomer version of clomiphene citrate (“clomid”), otherwise known as enclomiphene citrate.  Now truthfully as we have discussed in the past clomid has a significant amount of research showing it increases testosterone to normal levels in hypogonadal men (Read – Bridging with Clomid).  So why develop Enclomiphene?  The answer is simple, it’s what drives every pharma company – profits.  Unfortunately clomid is not approved by the FDA to treat hypogonadal males.  Otherwise it would be used more frequently.    If Repros Therapeutics is able to get FDA approval for enclomiphene (Androxal), there is a very real likelihood this could become the most commonly prescribed method of hormone replacement ever.  Now they aren’t fully invested into this product simply for profits, they do believe that the single isomer version of clomid might actually work a bit better.

Now you may be thinking why ditch traditional testosterone injections, and transdermal gels.  There are three reasons enclomiphene is superior to test injections and trandermals.  First, enclomiphene is an oral pill.  Meaning no doctor’s visits for injections, or no botched painful injections by the user themselves.  It’s also superior to transdermals because there is no transfer risk to children, females, and animals.

The second reason why this is superior to testosterone replacement is that it does not suppress follicle stimulating hormone (FSH), and leutinizing hormone (LH), and subsequently can maintain (not suppress) fertility.  Being able to conceive a child is important to many men.

The third and final reason, which is simply cosmetic, is that enclomiphene maintains testicular size.  Unfortunately one side effect of testosterone replacement is shrunken nuts.

Enclomiphene Phase IIB Study

The latest Phase II study was completed by physicians from Repros, as well as doctors from Baylor University (Listen to Episode #11 to learn more about these researchers).  The goal was to simply compare testosterone, LH, FSH, and semen parameters after oral administration of 12.5 mg’s and 25 mg’s of enclomiphene or 1% Testosterone Gel.  Here are some other key points of the study:

  • Men had to have below 250 ng/dL testosterone levels to participate in the study
  • Men were predominantly white males
  • Average age was between 49 and 51
  • 3 month study
  • The 12.5 mg/day group included 18 participants that finished the study
  • 20 in the 25 mg/day group
  • 19 in the topical test group
  • 16 in the placebo group

Now I’ll put the entire table below for your viewing pleasure, but as you can see testosterone levels increased from low, to normal for all three treatment groups.  There was no statistical difference between the treatment group increases.  Meaning they all worked equally as well.


The unique aspect of enclomiphene was seen in the FSH and LH values.  Both increased in the enclomiphene groups, and of course decreased in the testosterone gel group.  As you might imaging this corresponded to sperm count, which remained high in the enclomiphene groups, but not the testosterone group.

enclomiphene lh fsh

None of this is surprising, in fact, it’s exactly what we might expect from clomid administration.  Nonetheless as I write this Phase III studies in larger populations are occurring.  In my opinion, there is not much in the way of this future Hormone Replacement option.

enclomiphene sperm

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