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Details with Side Effects
Women of Childbearing Potential and Pregnancy
Before starting treatment with ZOLADEX, pregnancy must be excluded for women using ZOLADEX for benign gynecological conditions. Women of childbearing potential should be advised to avoid becoming pregnant.
Effective nonhormonal contraception must be used by all premenopausal women during ZOLADEX therapy and for 12 weeks following discontinuation of therapy. When used every 28 days, ZOLADEX usually inhibits ovulation and stops menstruation; however, pregnancy prevention is not ensured. Effects on reproductive function are expected to occur with chronic administration as a result of the anti-gonadotrophic properties of the drug.
Based on mechanism of action in humans and findings of increased pregnancy loss in animal studies, ZOLADEX can cause fetal harm when administered to a pregnant woman. If this drug is used during pregnancy for the palliative treatment of breast cancer, then the patient should be apprised of the potential hazard to the fetus [see Use In Specific Populations].
Tumor Flare Phenomenon
Initially, ZOLADEX, like other GnRH agonists, causes transient increases in serum levels of testosterone in men with prostate cancer, and estrogen in women with breast cancer. Transient worsening of symptoms, or the occurrence of additional signs and symptoms of prostate or breast cancer, may occasionally develop during the first few weeks of ZOLADEX treatment. A small number of patients may experience a temporary increase in bone pain, which can be managed symptomatically.
As with other GnRH agonists, isolated cases of ureteral obstruction and spinal cord compression have been observed in patients with prostate cancer. If spinal cord compression or renal impairment secondary to ureteral obstruction develops, standard treatment of these complications should be instituted. For extreme cases in prostate cancer patients, an immediate orchiectomy should be considered.
Hyperglycemia and Diabetes
Hyperglycemia and an increased risk of developing diabetes have been reported in men receiving GnRH agonists. Hyperglycemia may represent development of diabetes mellitus or worsening of glycemic control in patients with diabetes. Monitor blood glucose and/or glycosylated hemoglobin (HbA1c) periodically in patients receiving a GnRH agonist and manage with current practice for treatment of hyperglycemia or diabetes [see PATIENT INFORMATION].
Increased risk of developing myocardial infarction, sudden cardiac death and stroke has been reported in association with use of GnRH agonists in men. The risk appears low based on the reported odds ratios, and should be evaluated carefully along with cardiovascular risk factors when determining a treatment for patients with prostate cancer. Patients receiving a GnRH agonist should be monitored for symptoms and signs suggestive of development of cardiovascular disease and be managed according to current clinical practice [see PATIENT INFORMATION].
As with other GnRH agonists or hormonal therapies (antiestrogens, estrogens, etc.), hypercalcemia has been reported in some prostate and breast cancer patients with bone metastases after starting treatment with ZOLADEX. If hypercalcemia does occur, appropriate treatment measures should be initiated.
Hypersensitivity, antibody formation and acute anaphylactic reactions have been reported with GnRH agonist analogues [see CONTRAINDICATIONS].
Of 115 women worldwide treated with ZOLADEX and tested for development of binding to goserelin following treatment with ZOLADEX, one patient showed low-titer binding to goserelin. On further testing of this patient's plasma obtained following treatment, her goserelin binding component was found not to be precipitated with rabbit antihuman immunoglobulin polyvalent sera. These findings suggest the possibility of antibody formation.
Carcinogenesis, Mutagenesis, Impairment of Fertility
Subcutaneous implantation of goserelin in male and female rats once every 4 weeks for 1 year and recovery for 23 weeks at doses of about 80 and 150 mcg/kg (males) and 50 and 100 mcg/kg (females) daily resulted in an increased incidence of pituitary adenomas. An increased incidence of pituitary adenomas was also observed following subcutaneous implant of goserelin in rats at similar dose levels for a period of 72 weeks in males and 101 weeks in females. The relevance of the rat pituitary adenomas to humans has not been established. Subcutaneous implants of goserelin every 3 weeks for 2 years delivered to mice at doses of up to 2400 mcg/kg/day resulted in an increased incidence of histiocytic sarcoma of the vertebral column and femur. Human dose/exposure multiples could not be calculated from available animal data.
Mutagenicity tests using bacterial and mammalian systems for point mutations and cytogenetic effects have provided no evidence for mutagenic potential.
Administration of goserelin led to changes that were consistent with gonadal suppression in both male and female rats as a result of its endocrine action. In male rats administered 500-1000 mcg/kg/day, a decrease in weight and atrophic histological changes were observed in the testes, epididymis, seminal vesicle and prostate gland with complete suppression of spermatogenesis. In female rats administered 50-1000 mcg/kg/day, suppression of ovarian function led to decreased size and weight of ovaries and secondary sex organs; follicular development was arrested at the antral stage and the corpora lutea were reduced in size and number. Except for the testes, almost complete histologic reversal of these effects in males and females was observed several weeks after dosing was stopped; however, fertility and general reproductive performance were reduced in those that became pregnant after goserelin was discontinued. Fertile matings occurred within 2 weeks after cessation of dosing, even though total recovery of reproductive function may not have occurred before mating took place; and, the ovulation rate, the corresponding implantation rate, and number of live fetuses were reduced.
Based on histological examination, drug effects on reproductive organs were reversible in male and female dogs administered 107-214 mcg/kg/day goserelin when drug treatment was stopped after continuous administration for 1 year. Human dose/exposure multiples could not be calculated from available animal data.
Use In Specific Populations
Pregnancy Category D in patients with advanced breast cancer.
Pregnancy Category X in patients with endometriosis and endometrial thinning.
ZOLADEX is contraindicated during pregnancy unless ZOLADEX is being used for palliative treatment of advanced breast cancer. There are no adequate and well-controlled studies in pregnant women using ZOLADEX. Based on mechanism of action in humans and findings of increased pregnancy loss in animal studies, ZOLADEX can cause fetal harm when administered to a pregnant woman. If this drug is used during pregnancy, the patient should be apprised of the potential hazard to the fetus. There is an increased risk for pregnancy loss due to expected hormone changes that occur with ZOLADEX treatment.
ZOLADEX crosses the placenta in rats and rabbits following subcutaneous administration. Administration of goserelin to pregnant rats and rabbits during organogenesis resulted in increased preimplantation loss and increased resorptions. When pregnant rats received goserelin throughout gestation and lactation, there was a dose-related increase in umbilical hernia in offspring. In additional reproduction studies in rats, goserelin decreased fetus and pup survival. Human dose/exposure multiples could not be calculated from available animal data.
Actual animal doses: rat ( ≥ 2 mcg/kg/day for pregnancy loss; ≥ 10 mcg/kg/day for umbilical hernia in offspring); rabbits ( > 20 mcg/kg/day).
It is not known if goserelin is excreted in human milk. Goserelin is excreted in the milk of lactating rats. Because many drugs are excreted in human milk and because of the potential for serious adverse reactions in nursing infants from ZOLADEX, a decision should be made to either discontinue nursing or discontinue the drug, taking into account the importance of the drug to the mother.
Safety and effectiveness in pediatric patients have not been established.
There is no need for any dosage adjustment when administering ZOLADEX to male geriatric patients. ZOLADEX has not been studied in women over 65 years.
In clinical trials with the solution formulation of goserelin, male patients with impaired renal function (creatinine clearance < 20 mL/min) had a total body clearance and serum elimination half-life of 31.5 mL/min and 12.1 hours, respectively, compared to 133 mL/min and 4.2 hours for subjects with normal renal function (creatinine clearance > 70 mL/min). In females, the effects of reduced goserelin clearance due to impaired renal function on drug efficacy and toxicity are unknown. Pharmacokinetic studies in patients with renal impairment do not indicate a need for dose adjustment with the use of the depot formulation.
The total body clearances and serum elimination half-lives were similar between normal subjects and patients with moderate hepatic impairment (alanine transaminase < 3xULN and asparate aminotransferase < 3xULN) when treated with a 250 mcg subcutaneous formulation of goserelin. This pharmacokinetic study indicates that no dose adjustment is needed in patients with moderately impaired liver function. There is no pharmacokinetic data with goserelin in patients with severe hepatic insufficiency.
Last reviewed on RxList: 7/1/2013
This monograph has been modified to include the generic and brand name in many instances.
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