General
Because of potential effects of beta-adrenergic blocking agents on blood pressure and pulse, these agents should be used with caution in patients with cerebrovascular insufficiency. If signs or symptoms suggesting reduced cerebral blood flow develop following initiation of therapy with TIMOPTIC-XE, alternative therapy should be considered.
There have been reports of bacterial keratitis associated with the use of multiple-dose
containers of topical ophthalmic products. These containers had been inadvertently
contaminated by patients who, in most cases, had a concurrent corneal disease
or a disruption of the ocular epithelial surface. (See PRECAUTIONS, Information
for Patients.)
Choroidal detachment after filtration procedures has been reported with the administration of aqueous suppressant therapy (e.g. timolol).
Angle-closure glaucoma: In patients with angle-closure glaucoma,
the immediate objective of treatment is to reopen the angle. This may require
constricting the pupil. Timolol maleate has little or no effect on the pupil.
TIMOPTIC-XE should not be used alone in the treatment of angle-closure glaucoma.
Anaphylaxis: While taking beta-blockers, patients with a history
of atopy or a history of severe anaphylactic reactions to a variety of allergens
may be more reactive to repeated accidental, diagnostic, or therapeutic challenge
with such allergens. Such patients may be unresponsive to the usual doses of
epinephrine used to treat anaphylactic reactions.
Muscle Weakness: Beta-adrenergic blockade has been reported to
potentiate muscle weakness consistent with certain myasthenic symptoms (e.g.,
diplopia, ptosis, and generalized weakness). Timolol has been reported rarely
to increase muscle weakness in some patients with myasthenia gravis or myasthenic
symptoms.
Carcinogenesis, Mutagenesis, Impairment of Fertility
In a two-year study of timolol maleate administered orally to rats, there was a statistically significant increase in the incidence of adrenal pheochromocytomas in male rats administered 300 mg/kg/day (approximately 42,000 times the systemic exposure following the maximum recommended human ophthalmic dose). Similar differences were not observed in rats administered oral doses equivalent to approximately 14,000 times the maximum recommended human ophthalmic dose.
In a lifetime oral study in mice, there were statistically significant increases
in the incidence of benign and malignant pulmonary tumors, benign uterine polyps,
and mammary adenocarcinomas in female mice at 500 mg/kg/day (approximately 71,000
times the systemic exposure following the maximum recommended human ophthalmic
dose), but not at 5 or 50 mg/kg/day (approximately 700 or 7,000, respectively,
times the systemic exposure following the maximum recommended human ophthalmic
dose). In a subsequent study in female mice, in which post-mortem examinations
were limited to the uterus and the lungs, a statistically significant increase
in the incidence of pulmonary tumors was again observed at 500 mg/kg/day.
The increased occurrence of mammary adenocarcinomas was associated with elevations in serum prolactin, which occurred in female mice administered oral timolol at 500 mg/kg/day, but not at oral doses of 5 or 50 mg/kg/day. An increased incidence of mammary adenocarcinomas in rodents has been associated with administration of several other therapeutic agents that elevate serum prolactin, but no correlation between serum prolactin levels and mammary tumors has been established in humans. Furthermore, in adult human female subjects who received oral dosages of up to 60 mg of timolol maleate (the maximum recommended human oral dosage), there were no clinically meaningful changes in serum prolactin.
Timolol maleate was devoid of mutagenic potential when tested in vivo
(mouse) in the micronucleus test and cytogenetic assay (doses up to 800 mg)
and in vitro in a neoplastic cell transformation assay (up to 100 mcg/mL).
In Ames tests, the highest concentrations of timolol employed, 5,000 or 10,000
mcg/plate, were associated with statistically significant elevations of revertants
observed with tester strain TA 100 (in seven replicate assays), but not in the
remaining three strains. In the assays with tester strain TA 100, no consistent
dose response relationship was observed, and the ratio of test to control revertants
did not reach 2. A ratio of 2 is usually considered the criterion for a positive
Ames test.
Reproduction and fertility studies in rats demonstrated no adverse effect on male or female fertility at doses up to 21,000 times the systemic exposure following the maximum recommended human ophthalmic dose. Pregnancy:
Teratogenic Effects — Pregnancy Category C. Teratogenicity studies
with timolol in mice, rats, and rabbits at oral doses up to 50 mg/kg/day (7,000
times the systemic exposure following the maximum recommended human ophthalmic
dose) demonstrated no evidence of fetal malformations. Although delayed fetal
ossification was observed at this dose in rats, there were no adverse effects
on postnatal development of offspring. Doses of 1000 mg/kg/day (142,000 times
the systemic exposure following the maximum recommended human ophthalmic dose)
were maternotoxic in mice and resulted in an increased number of fetal resorptions.
Increased fetal resorptions were also seen in rabbits at doses of 14,000 times
the systemic exposure following the maximum recommended human ophthalmic dose,
in this case without apparent maternotoxicity.
There are no adequate and well-controlled studies in pregnant women. TIMOPTIC-XE
should be used during pregnancy only if the potential benefit justifies the
potential risk to the fetus.
Nursing Mothers
Timolol maleate has been detected in human milk following oral and ophthalmic
drug administration. Because of the potential for serious adverse reactions
from TIMOPTIC-XE in nursing infants, a decision should be made whether to discontinue
nursing or to discontinue the drug, taking into account the importance of the
drug to the mother.
Pediatric Use
Safety and effectiveness in pediatric patients have not been established.
Geriatric Use
No overall differences in safety or effectiveness have been observed between elderly and younger patients.
Last updated on RxList: 2/26/2009