Care During Chemotherapy and Beyond


Generic Name: Triptorelin Pamoate

Drug Type:

Trelstar® is a hormone therapy. It is classified as a gonadotropin releasing hormone (GnRH) agonist (for more detail, see "How Trelstar® Works" section below).

What Trelstar® Is Used For:

  • The palliative treatment of advanced prostate cancer

Note: If a drug has been approved for one use, physicians may elect to use this same drug for other problems if they believe it may be helpful.

How Trelstar® Is Given:

  • Injection into the muscle (intramuscular, IM)
  • 3.75 mg once every 4 weeks or
  • 11.25 mg once every 12 weeks or
  • 22.5 mg once every 24 weeks
  • Your doctor will determine your dose and schedule

Side Effects:

Important things to remember about the side effects of Trelstar®:

  • Most people do not experience all of the side effects listed.
  • Side effects are often predictable in terms of their onset and duration.
  • Side effects are almost always reversible and will go away after treatment is complete.
  • There are many options to help minimize or prevent side effects.
  • There is no relationship between the presence or severity of side effects and the effectiveness of the medication.

The following side effects are common (occurring in greater than 30%) for patients taking Trelstar®:

These side effects are less common side effects (occurring in about 10-29%) of patients receiving Trelstar®:

Trelstar® may cause a short-term (within first 2 weeks of treatment) increase in testosterone serum levels. When this is used for prostate cancer the resulting "tumor flare" can cause temporary increase of bone pain, swelling of the prostate that blocks urine flow or swelling around tumor in the spine causing compression of the spinal cord. If you are noticing increased weakness, numbness or tingling in arms or legs, or difficulty with urination, report these symptoms to your health care provider immediately.

High blood sugar and an increased risk of developing diabetes have been reported in men receiving this type of medication.

Rare but significant side effects may include heart problems such as arrhythmias, congestive heart failure or heart attack (<5%).

Not all side effects are listed above. Some that are rare (occurring in less than 10% of patients) are not listed here. However, you should always inform your health care provider if you experience any unusual symptoms.

When to contact your doctor or health care provider:

Contact your health care provider immediately, day or night, or go to the Emergency Room if you should experience any of the following symptoms:

  • Urinary retention or inability to urinate
  • Weakness, numbness or tingling in arms or legs
  • Chest pain or pressure
  • Very bad headache
  • Sudden change in eyesight, eye pain or irritation

The following symptoms require medical attention, but are not an emergency. Contact your health care provider within 24 hours of noticing any of the following:

  • Extreme fatigue (unable to carry on self-care activities)
  • Swelling of the feet or ankles. Sudden weight gain.
  • Swelling, redness and/or pain in one leg or arm and not the other
  • Changes in mood or memory
  • More bone pain, blood in the urine. Most often gets better 1 to 2 weeks after care has started.
  • More trips to the bathroom, more thirst, or weight loss

Always inform your health care provider if you experience any unusual symptoms.


  • Before starting Trelstar® treatment, make sure you tell your doctor about any other medications you are taking (including prescription, over-the-counter, vitamins, herbal remedies, etc.).
  • Tell dentists, surgeons, and other doctors that you are taking this medication.
  • Pregnancy category X (Trelstar® may cause fetal harm).
  • Do not conceive a child while taking Trelstar®. Barrier methods of contraception, such as condoms, are recommended.

Self-Care Tips:

  • If you are experiencing hot flashes, wearing light clothing, staying in a cool environment, and putting cool cloths on your head may reduce symptoms. Consult your health care provider if these worsen, or become intolerable.
  • Avoid sun exposure. Wear SPF 15 (or higher) sunblock and protective clothing.
  • In general, drinking alcoholic beverages should be kept to a minimum or avoided completely. You should discuss this with your doctor.
  • Get plenty of rest.
  • Maintain good nutrition.
  • If you experience symptoms or side effects, be sure to discuss them with your health care team. They can prescribe medications and/or offer other suggestions that are If you experience symptoms or side effects, be sure to discuss them with your health care team. They can prescribe medications and/or offer other suggestions that are effective in managing such problems.

Monitoring and Testing:

You will be checked regularly by your health care professional while you are taking Trelstar®, to monitor side effects and check your response to therapy. Periodic blood work to monitor your complete blood count (CBC) as well as the function of other organs (such as your kidneys and liver) may also be ordered by your doctor.

How Trelstar® Works:

Hormones are chemical substances that are produced by glands in the body, which enter the bloodstream and cause effects in other tissues. For example, the hormone testosterone, made in the testicles and is responsible for male characteristics such as deepening voice and increased body hair. The use of hormone therapy to treat cancer is based on the observation that receptors for specific hormones that are needed for cell growth are on the surface of some tumor cells. Hormone therapy can work by stopping the production of a certain hormone, blocking hormone receptors, or substituting chemically similar agents for the active hormone, which cannot be used by the tumor cell. Different types of hormone therapies are categorized by their function and/or the type of hormone that is affected.

Trelstar® is classified as a Gonadotropin Releasing Hormone (GnRH) agonist. In general, a GnRH agonist is used when the desired end result is to reduce the amount of reproductive hormones circulating in the body. Medications in this class typically work by forcing the body’s pituitary gland to first overproduce follicle-stimulating hormone (FSH) and luteinizing hormone (LH), which both play a role in the body’s production of estrogen and testosterone. Over time, this causes the pituitary to exhaust its normal supply of FSH and LH, which then results in lowered levels of these hormones, as well as estrogen and testosterone, in the body. In adult men with advanced prostate cancer, a GnRH agonist can also be used to help lower testosterone levels, which can be beneficial in stopping or slowing the growth of abnormal prostate tissue. The drug does not have a direct effect on the cancer, only on the testicles or ovaries. The resulting lack of testosterone (in men) and estrogen (in women) interferes with stimulating cell growth in testosterone or estrogen dependent cancer cells.

Cancer of the prostate depends on the male hormone testosterone for its growth. If the amount of testosterone is reduced it is possible to slow down or shrink the cancer.

Note: We strongly encourage you to talk with your health care professional about your specific medical condition and treatments. The information contained in this website is meant to be helpful and educational, but is not a substitute for medical advice. is designed to provide the latest information about chemotherapy to patients and their families, caregivers and friends. For information about the 4th Angel Mentoring Program visit