Originally Posted by missing article

Types of Progesterone:
Synthetic Progesterone (Provera)
Synthetic progesterone, which can be administered orally or via injection, is most commonly used to trigger menstruation. Because of its chemical makeup, it is less likely to cause some of the undesirable size effects of natural progesterone, such as sleepiness or dizziness. Unlike natural progesterone however, synthetic progesterone is generally *not* considered safe to use during pregnancy, which should be ruled out prior to its use.

The remaining types of progesterone, described below, are all natural forms.

Oral Progesterone
Natural oral progesterone, such as Prometrium pills, is used primarily as a supplement in the luteal phase for patients undergoing natural or IUI cycles. The primary advantage of oral progesterone is its convenience; patients do have not have to learn to give themselves injections or deal with the discharge that may occur with vaginal application. Despite its appeal, however, oral progesterone has several disadvantages. Most seriously, at least one study suggests that it may be associated with lower success rates than some other forms of progesterone; it has been hypothesized that oral progesterone may be more effective at raising serum progesterone levels than at raising the level of progesterone within the uterine lining itself, which is where its true effect occurs. Additionally, oral progesterone is metabolized by the liver, and the byproducts may cause side effects such as dizziness or sleepiness.

Recently, some doctors have begun to have patients administer these same progesterone pills vaginally. Few data are yet available on the efficacy of this approach.

Progesterone Suppositories
Progesterone suppositories are compounded by individual pharmacists and consist of natural progesterone suspended in a base similar to cocoa butter. Upon insertion, the warmth of the body causes the suppository to melt and release the progesterone. Since suppositories are vaginally administered, the liver does not produce the high number of side effect-causing metabolites that can occur with natural progesterones taken orally. The vaginal administration also allows the progesterone to be targeted more specifically to the uterine area. Many women, however, find the discharge associated with suppositories to be overly messy or uncomfortable and there is some question as to how long the progesterone is effective after insertion. Additionally, it can be difficult to find a pharmacy that will compound the suppositories, and the individualized process may cause a lower level of dosing accuracy and quality control. Finally, some women may be sensitive to the suspending substance.

Bioadhesive Gel (Crinone)
Crinone gel is also applied vaginally. In contrast to suppositories, however, the progesterone is suspended in a bioadhesive gel (sold without progesterone under the brand name Replens) and is packaged in a tampon-like applicator. Crinone gel is highly efficient at the uterine level; in fact, the progesterone stays so concentrated in the uterus that Crinone often has minimal impact on serum progesterone levels. Crinone is frequently used as a progesterone supplement in IUI and IVF cycles.

This uterine level impact is one of the primary advantages of Crinone, as is the fact that many patients only need to apply it once a day. For many women, Crinone is far better at delaying premature onset of menstruation than are suppositories or oral progesterone. Some women do, however, find that the suspension gel accumulates in the vagina and may need to be removed every couple of days; additionally, patients occasionally experience vaginal irritation as a result of the build-up.

Injectible Progesterone
Injectible progesterone consists of progesterone suspended in an oil, commonly sesame or peanut. Used most frequently in IVF cycles, progesterone in oil is normally injected intramuscularly once a day, most commonly in a dose of one cubic centimeter (cc).

Progesterone in oil is highly effective at the uterine level; many physicians consider it to be the gold standard for progesterone supplementation, particularly in high stakes in vitro fertilization cycles. Additionally, unlike Crinone, progesterone in oil supplementation is also reflected in serum tests, allowing levels to be more easily, albeit indirectly, monitored. The once a day dosing is convenient for patients, and the cost is quite low, often only several dollars a day for a patient taking 1 cc.

For many women, the primary disadvantage of progesterone in oil is the manner in which it is administered. In addition to being intramuscular, progesterone injections must be performed using a 20 or 22 gauge needle to accommodate the relatively high viscosity of the oily solution. This gauge is larger than that used for most other infertility medications, and patients often find the change intimidating. Additionally, like progesterone suppositories, progesterone in oil normally has to be compounded by a specialty pharmacy or mail ordered. Finally, some women may be allergic to the oil in which the progesterone is most commonly suspended.

What about Progesterone Creams?
In contrast to the above products, progesterone creams are available over the counter. These products deliver a small amount of supplemental progesterone, and absorption may vary significantly from person to person. These creams may provide a bit of “insuranceú to a woman with a fairly normal cycle, but the dosages are not high enough to treat significant hormonal issues. When you are trying to conceive, it is always a good idea to consult a knowledgeable professional about the use of any drug that might affect fertility.

What is the Best Form?
As is often the case, there is no one single treatment that is best for all women. Although oral progesterone may be sufficient for some women, Crinone and progesterone in oil do appear to be the most effective at the uterine level. The issue of whether either of these two supplementation forms is superior to the other remains unresolved. Some preliminary research suggests that progesterone in oil is superior at preventing bleeding in pregnancy, but that it may also delay bleeding in some cases where genetically abnormal pregnancies ultimately result in blighted ova. Definitive research is, however, yet to be done.