Eligard
Meaning of Eligard: A gel injection that shuts down testosterone production for months at a time, after first pushing the level higher.
Definition of Eligard
Eligard is a brand of leuprolide acetate given as an injection under the skin, used mainly for advanced prostate cancer. Leuprolide is a synthetic copy of the hormone that normally tells the pituitary gland to stimulate the testicles. Delivered continuously rather than in natural pulses, it exhausts that signal instead of driving it, so testosterone production falls to very low levels.
Why does testosterone matter in prostate cancer?
Most prostate cancer cells depend on androgens to grow, so removing the fuel shrinks the tumor and lowers the PSA blood level. This approach is called androgen deprivation therapy. It is not a cure, and cancers eventually adapt and grow again despite low testosterone, but it controls disease for a long period and relieves symptoms such as bone pain.
How does the drug actually work?
The pituitary responds to gonadotropin releasing hormone only when it arrives in pulses about once an hour. A gonadotropin releasing hormone agonist floods the receptor without pause. After an initial burst of stimulation the pituitary withdraws its receptors and stops responding, so the signal to the testicles ceases and testosterone falls to levels comparable to those after surgical removal of the testicles.
What is the flare?
Because the first effect is stimulation, testosterone rises sharply for one to two weeks before it falls. In someone with extensive disease this transient surge can worsen bone pain, aggravate urinary obstruction, or in rare cases press on the spinal cord. An androgen receptor blocker is commonly started shortly before or alongside the first injection to cover that period. Drugs of the antagonist class lower testosterone without any surge, which is one reason they are chosen when a flare would be dangerous.
What are the effects of low testosterone?
| Effect | What it looks like |
|---|---|
| Vasomotor | Hot flashes and sweats |
| Sexual | Loss of libido and erectile difficulty |
| Body composition | Muscle loss, weight gain, breast tenderness |
| Skeletal | Thinning of bone with prolonged use |
| Metabolic and mood | Higher blood sugar and lipids, fatigue, low mood |
The gel form solidifies into a small depot under the skin and releases drug steadily, which is what allows a single injection to cover one, three, four or six months depending on the strength given. Because testosterone suppression is monitored by blood tests rather than by symptoms, the timing of repeat injections is tracked closely.
Also known as
Used in a sentence
Eligard was given as a subcutaneous depot injection to maintain androgen deprivation.
Good to know
Agonists such as leuprolide raise testosterone briefly before suppressing it, and that flare can aggravate symptoms in the first weeks, whereas the antagonist drugs lower testosterone without a surge.