DRUGS WITH OCULAR SIDE EFFECTS OF RECENT CLINICAL IMPORTANCE
TAMOXIFEN (NOLVADEX®)
For
metastatic breast cancer, pancreatic cancer and malignant melanoma. Beginning
to be used as prophy-lactic long-term therapy in patients with a strong family
history of breast cancer. Clinicians should expect to see more patients for
follow-up ocular examinations who are receiving long-term tamoxifen therapy.
Clinical
Concerns
There
is minimal data on long-term (4–5+ years) exposure to this drug with
documented signif-icant ocular side effects. Thus, all data are preliminary.
Known
Side Effects
• Posterior subcapsular cataracts
• Decreased color perception
• Decreased vision
• Retina or macula: refractile bodies, edema,
degen-eration, pigmentary changes and hemorrhages
• Visual fields: constriction, scotomata
• Papilledema
• Optic neuritis
• Corneal deposits
• ERG changes
• Baseline ophthalmic examination within the
first year of starting tamoxifen therapy. This should include slit lamp
biomicroscopy of the anterior and posterior segments in combination with an
indi-rect ophthalmoscope or contact lens. Baseline color vision testing is
important.
• In keeping with the American Academy of
Ophthalmology’s current recommendations, there should be a complete eye
examination at least every 2 years for healthy adults. More frequent
examinations are required if ocular symp-toms occur.
• In the absence of macular edema or visual
impair-ment, the discovery of a limited number of intraretinal crystals does
not seem to warrant the discontinuation of therapy.
• Consultation with the oncologist is essential
if significant ocular findings occur.
• The presence of age-related maculopathy is
not a contraindication to the use of tamoxifen. However, informed consent may
be advisable in our litigious society.
• The presence of posterior subcapsular
cataracts is not an indication to stop tamoxifen therapy, as this condition usually progresses even if the drug
is discontinued.
• Significant loss of color vision may be a
valid reason to consider discontinuing the drug. Gorin recommends considering
stopping the drug for 3 months (in patients on prophylactic therapy) and
retesting at the end of that time. If color vision has returned to normal,
restart the drug and retest in 3 months. If at any time, there is a lack of
visual recovery or color vision loss progresses after therapy is stopped, the
ophthal-mologist may need to consult the oncologist and re-evaluate the
risk–benefit ratio of tamoxifen therapy.
The
incidence of ocular toxicity reported in the litera-ture ranges from 1.5% to
12%; however, the incidence of ocular complications that required stopping
ther-apy is less than 1%. Indications for stopping the drug require
consultation with the oncologist as there are many variables. Decreasing the
dosage may be an option if frequent ophthalmic observations are performed.
Indications
for stopping tamoxifen therapy include
• macular edema,
• decreased vision (with or without the presence
of refractile bodies or pigmentary change),
• optic neuritis,
• decreased color vision,
• presence of retinal crystals is not in itself
an indi-cation to stop the drug,
• retinal changes can occur even at 20 mg
dosage levels and
• optic neuritis has been reported at a total
dosage of only 2–3 g.
Related Topics
TH 2019 - 2023 pharmacy180.com; Developed by Therithal info.