Zoladex

Action

Synthetic form of luteinizing hormone-releasing hormone (LHRH); inhibits gonadotropin production by acting directly on pituitary gland. Enhances release of luteinizing hormone (LH), follicle-stimulating hormone (FSH), and testosterone, lowering testosterone and estradiol levels.

Availability

Implant: 3.6 mg, 10.8 mg (in preloaded syringes)

Indications and dosages

➣ Palliative treatment of advanced prostate cancer

Adults: 3.6 mg subcutaneously q 4 weeks or 10.8 mg subcutaneously q 12 weeks into upper abdominal wall

➣ Adjunct to radiation therapy and flutamide in stage B2-C prostate cancer

Adults: 3.6 mg subcutaneously q 4 weeks starting on day 1 of radiation or during last week of radiation. Alternatively, 3.6 mg subcutaneously 8 weeks before radiation, then 10.8 mg on day 28 or 3.6 mg at 4-week intervals starting 8 weeks before radiation, for a total of four doses (two depots before and two during radiation therapy).

➣ Palliative treatment of advanced breast cancer in pre- and perimenopausal women

Adults: 3.6 mg subcutaneously q 4 weeks. If serum estradiol doesn't fall to postmenopausal levels, may increase to 7.2 mg q 4 weeks.

➣ Endometriosis

Adults ages 18 and older: 3.6 mg subcutaneously q 4 weeks, continued for 6 months

➣ Endometrial thinning before ablation for dysfunctional uterine bleeding

Adults: 3.6 mg subcutaneously 4 weeks before surgery. Alternatively, initial 3.6-mg dose may be followed 4 weeks later by a second 3.6-mg dose, with surgery 2 to 4 weeks after second dose.

Contraindications

• Hypersensitivity to drug or its components or to GnRH, GnRH agonist analogs

• Pregnant patients

Precautions

Use cautiously in:

• risk factors for osteoporosis

• chronic alcohol or tobacco use

• patients receiving drugs that affect bone density

• hyperglycemia, cardiovascular risk factors

• breastfeeding patients

• children younger than age 18 (safety not established).

Administration

• Administer pretreatment pregnancy test to female of childbearing age.

• Know that drug should be given only by a clinician experienced in its use.

• Implant is placed subcutaneously into upper abdominal wall using aseptic technique. Give local anesthetic and stretch skin with one hand. Insert needle into subcutaneous fat, then change needle angle until it parallels abdominal wall. Push needle in until hub touches patient's skin, and withdraw about 1 ml before depressing plunger all the way.

• Don't aspirate after inserting needle. Blood will be visible in syringe if needle enters blood vessel.

See Don't give by I.V. route.

• Be aware that 10.8-mg implant should not be used in women.

• Be aware that if implant must be removed, it can be located by ultrasound.

Adverse reactions

CNS: headache, anxiety, depression, dizziness, fatigue, insomnia, lethargy, pain, emotional lability, weakness, cerebrovascular accident, spinal cord compression

CV: vasodilation, chest pain, hypertension, palpitations, peripheral edema, myocardial infarction, arrhythmias, sudden cardiac death

EENT: blurred vision

GI: nausea, vomiting, diarrhea, constipation, ulcer, anorexia

GU: urinary obstruction, lower urinary tract symptoms, breast swelling or tenderness, vaginitis, amenorrhea, infertility, decreased libido, erectile dysfunction, other sexual dysfunction, decreased testicular size, renal insufficiency

Hematologic: anemia

Musculoskeletal: increased bone pain, joint pain, decreased bone density

Metabolic: gout, hyperglycemia, hypercalcemia

Respiratory: dyspnea, chronic obstructive pulmonary disease, upper respiratory tract infection

Skin: rash, acne, diaphoresis, seborrhea

Other: hirsutism, chills, fever, hot flashes, infection, weight gain, tumor flare phenomenon, hypersensitivity, antibody formation, acute anaphylactic reactions

Interactions

Drug-diagnostic tests. Calcium, glucose, high- and low-density lipoproteins, triglycerides: increased levels

FSH, LH: initially increased, then decreased, levels

Patient monitoring

• Assess menstrual symptoms and watch for breakthrough bleeding.

See Monitor neurologic status. Watch closely for signs and symptoms of cerebrovascular accident.

See Closely monitor cardiovascular and respiratory status.

• Monitor blood glucose and glycosylated hemoglobin periodically.

Patient teaching

• Advise female patient to avoid pregnancy and to use a nonhormonal contraceptive method.

• Instruct patient to call prescriber if menstrual bleeding persists or breakthrough bleeding occurs.

• Inform patient that menstruation may be delayed after therapy ends.

See Instruct patient to recognize and immediately report signs and symptoms of hyperglycemia, and cardiovascular or neurological adverse reactions.

• As appropriate, review all other significant and life-threatening adverse reactions and interactions, especially those related to the tests mentioned above.