Testolactone (Systemic)
VA CLASSIFICATION
Primary: AN500
Commonly used brand name(s): Teslac.
Note: For a listing of dosage forms and brand names by country availability, see Dosage Forms section(s).
†Not commercially available in Canada.
Category:
Antineoplastic—
Indications
Accepted
—Testolactone has been used as adjunctive therapy in the palliative treatment of advanced or disseminated breast cancer in postmenopausal women when hormone therapy is indicated; however testolactone generally has been replaced by more effective agents {03}.
—Testolactone is not recommended for treatment of breast cancer in males.
Pharmacology/Pharmacokinetics
Physicochemical characteristics:
Molecular weight—
300.40 {04}
Mechanism of action/Effect:
Testolactone is structurally similar to androgens but is not known to cause virilization. The mechanism of its antineoplastic activity is unknown, although it is reported to inhibit steroid aromatase activity (the effect may be noncompetitive and irreversible {01}) and reduce estrone synthesis from adrenal androstenedione (the major source of estrogen in postmenopausal women) {01}.
Absorption:
Well absorbed from the gastrointestinal tract.
Biotransformation:
Hepatic.
Onset of action:
Clinical effects may not be apparent for 6 to 12 weeks.
Elimination:
Renal.
Precautions to Consider
Carcinogenicity/Mutagenicity
Studies have not been done in either animals or humans {01}.
Pregnancy/Reproduction
Pregnancy—
Adequate and well-controlled studies in humans have not been done.
Studies in rats at doses 5 to 15 times the recommended human dose have found that testolactone causes increased fetal mortality, increased abnormal fetal development, and increased mortality in growing pups. It did not cause teratogenicity in rabbits given 2.5 to 7.5 times the recommended human dose. {01}
FDA Pregnancy Category C.
Breast-feeding
It is not known whether testolactone is distributed into breast milk. However, problems in humans have not been documented.
Geriatrics
No information is available on the relationship of age to the effects of testolactone in geriatric patients.
Drug interactions and/or related problems
The following drug interactions and/or related problems have been selected on the basis of their potential clinical significance (possible mechanism in parentheses where appropriate)—not necessarily inclusive (» = major clinical significance):
Anticoagulants, coumarin- or indandione-type (effects may be increased by concurrent use of testolactone; dosage adjustment of oral anticoagulants may be necessary)
{01}
Laboratory value alterations
The following have been selected on the basis of their potential clinical significance (possible effect in parentheses where appropriate)—not necessarily inclusive (» = major clinical significance):
With physiology/laboratory test values
Calcium concentrations, serum (may be increased; immobilized patients are especially likely to develop hypercalcemia)
Creatinine and
17-Ketosteroid (urinary concentrations may be increased)
Estradiol measured by radioimmunoassay (concentrations may be decreased {01})
Medical considerations/Contraindications
The medical considerations/contraindications included have been selected on the basis of their potential clinical significance (reasons given in parentheses where appropriate)— not necessarily inclusive (» = major clinical significance).
Risk-benefit should be considered when the following medical problems exist
» Cardiorenal disease
» Hypercalcemia
» Sensitivity to testolactone{01}
Patient monitoring
The following are especially important in patient monitoring (other tests may be warranted in some patients, depending on condition; » = major clinical significance):
» Calcium concentrations, serum (recommended at periodic intervals, especially in patients with active remission of bone metastases {01})
Side/Adverse Effects
The following side/adverse effects have been selected on the basis of their potential clinical significance (possible signs and symptoms in parentheses where appropriate)—not necessarily inclusive:
Those indicating need for medical attention
Incidence less frequent
Peripheral neuropathies (numbness or tingling of fingers, toes, or face)
Those indicating need for medical attention only if they continue or are bothersome
Incidence less frequent
Diarrhea
loss of appetite
nausea or vomiting
pain or swelling in feet or lower legs
swelling or redness of tongue
Patient Consultation
As an aid to patient consultation, refer to Advice for the Patient, Testolactone (Systemic).
In providing consultation, consider emphasizing the following selected information (» = major clinical significance):
Before using this medication
» Conditions affecting use, especially:
Sensitivity to testolactone
Pregnancy—Causes increased fetal and pup mortality and abnormal fetal development in rats
Other medical problems, especially cardiorenal disease
Proper use of this medication
» Importance of not taking more or less medication than the amount prescribed
» Possible nausea and vomiting; importance of continuing medication despite stomach upset
Checking with physician if vomiting occurs shortly after dose is taken
» Proper dosing
Missed dose: Taking as soon as possible, not taking if almost time for next dose; not doubling doses; checking with physician if two or more doses in a row are missed
» Proper storage
Precautions while using this medication
» Importance of close monitoring by the physician
Side/adverse effects
Signs of potential side effects, especially peripheral neuropathies
Physician or nurse can help in dealing with side effects
General Dosing Information
Patients receiving testolactone should be under supervision of a physician experienced in cancer chemotherapy.
If hypercalcemia occurs, therapy with testolactone should be withdrawn and the patient treated with large volumes of fluid.
Testolactone should be given for at least 3 months before it is considered ineffective, unless active progression of the disease occurs.
Oral Dosage Forms
TESTOLACTONE TABLETS USP
Usual adult dose
Breast carcinoma
Oral, 250 mg four times a day.
Strength(s) usually available
U.S.—
50 mg (Rx) [Teslac]
Canada—
Not commercially available.
Packaging and storage:
Store below 40 °C (104 °F), preferably between 15 and 30 °C (59 and 86 °F), unless otherwise specified by manufacturer. Store in a tight container.
Revised: 09/30/1997
References
Note: References used in the development and subsequent revisions of this monograph have not been incorporated into the database and therefore are not listed below.
- Teslac package insert (Squibb—US), Rev 9/87.
- no reference
- Reviewers' responses to Hematologic-Oncologic Disease Advisory Panel Memo #9 of 1/30/97.
- Canada JR, editor. USP dictionary of USAN and international drug names 1998. Rockville, MD: The United States Pharmacopeial Convention, Inc; 1997. p. 720.
