By David Tolson
One of the primary issues concerning steroids and prohormones is that of optimal delivery. While most drugs and supplements are taken orally, there are a number of reasons why this method is largely ineffective with most prohormones. When taken orally, these compounds are extensively metabolized in the liver, making the dose used much larger than the amount that gets through. This may also place undue stress on the liver, especially with certain substances. Because of this, other delivery methods, such as transdermal, sublingual, and intranasal, have all become popularized, and each has advantages and disadvantages. This article discusses the compound hydroxypropyl-beta cyclodextrin (HPBCD), which can be used to facilitate prohormone delivery in a number of ways.
Cyclodextrins are a group of compounds that are commonly used in medicine to increase the aqueous solubility of drug substances by complexation . Cyclodextrins are cyclic oligosaccarides, or sugars, which contain alpha-1,4 linked glucopyranose units (in the case of beta-cyclodextrins, seven of these units) in a truncated cone shape . This results in a molecule that has an internal cavity that is hydrophobic and easily forms a complex with a steroid/prohormone molecule, while the outer surface of the cyclodextrin is hydrophilic, and this makes the complex easily dissolvable in water [2-4]. This renders prohormones much more bioavailable, and cyclodextrins are capable of enhancing nasal, sublingual, and transdermal delivery [5-6], among others. Moreover, cyclodextrins will cause much less irritation than other methods [3, 7].
The cyclodextrin of choice for prohormone delivery is HPBCD. When compared to other testosterone beta-cyclodextrin complexes, HPBCD was 1,533 percent more soluble in water, while another study found that HPBCD-steroid complexes were effective while beta-cyclodextrin-steroid complexes were not . HPBCD also has an excellent safety profile. Sublingual delivery
Sublingual delivery (administered under the tongue) presents an attractive alternative to traditional oral administration. Because of the limited surface area, the amount of prohormone that can be absorbed at one time appears to be 25 milligrams or less. However, when compared to oral delivery, even this amount is advantageous. One study found that a cyclodextrin complex containing 10 mg of testosterone delivered sublingually raised testosterone levels by 900% over baseline, with a 485% elevation at the two hour point. In contrast, even 200 mg of oral testosterone only raises levels by around 500% at the peak. A study comparing oral and cyclodextrin complexed 4-androstenediol also found that the sublingual version lead to a 261% greater increase in testosterone with one quarter of the dose, with the peak levels at 40 as opposed to 90 minutes. 
All in all, sublingual delivery is much more effective than oral for the amount used, but it does require more frequent dosing. Sublingual prohormones are usually taken 3-5 times daily. Intranasal delivery
Intranasal delivery takes the trend of sublingual delivery even further. It is doubtful that more than 20 mg at a time will be absorbed using this method, and blood levels quickly spike 15 minutes after delivery and then dissipate to baseline by 90 minutes. Running a cycle using this method is impractical, as one has to dose up to 10 times daily. However, bioavailability is further increased – intranasal delivery has the highest bioavailability of all prohormone delivery methods, short of injection . Additionally, intranasal delivery provides the most direct route to the brain [6, 7]. For these reasons, this method has become popular for pre-workout stimulant purposes. Many people report increased workout intensity from intranasal prohormones. DHT precursors are best suited to this purpose, although some other prohormones may make effective pre-workout stimulants as well. Conclusion
HPBCD complexes can allow for a number of novel effective prohormone delivery methods. Each one has unique advantages and disadvantages.