Dr. Bob's Psychopharmacology Tips

Lens changes in association with quetiapine

Date: Tue, 3 Feb 1998 23:35:22 -0500 (EST)
From: Jason B Rosenstock <jasonr+@pitt.edu>
Subject: Lens changes in association with quetiapine

Culled from quetiapine's product labelling:

The development of cataracts was observed in association with quetiapine treatment in chronic dog studies. Lens changes have also been observed in patients during long-term treatment, but a causal relationship to use has not been established. Nevertheless, the possibility of lenticular changes cannot be excluded at this time. Therefore examination of the lens by methods adequate to detect cataract formation, such as slit lamp exam or other appropriately sensitive methods, is recommended at initiation of treatment or shortly thereafter, and at 6 month intervals during chronic treatment.

In dogs receiving quetiapine for 6 or 12 mo. but not for 1 mo., focal triangular cataracts occurred at the junction of posterior sutures in the outer cortex of the lens at a dose of 100 mg/kg, or 4 x the maximum recommended human dose on a mg/m^2 basis. This finding may be due to inhibition of cholesterol biosynthesis by quetiapine. Quetiapine caused a dose related reduction in plasma cholesterol levels in repeat-dose dog and monkey studies; however, there was no correlation between plasma cholesterol and the presence of cataracts in individual dogs... Drug-related cataracts have not been seen in any other species; however, in a 1-year study in monkeys, a striated appearance of the anterior lens surface was detected in 2/7 females at a dose of 225 mg/kg or 5.5 x the maximum recommended human dose on a mg/m^2 basis.

From: Mike Browne <mbrow@sympatico.ca>
Subject: Lens changes in association with quetiapine
Date: Thu, 19 Mar 1998 19:32:14 -0500

The suggestion (at least for Canadians) from the company is that patients can be started on quetiapine without the opthalmology workup and that if they seem to be doing OK they can then be sent for it, ie, there is no need to delay starting the drug for the eye exam. They also state the exam does not need to be done by a specialist.

I guess folks in the States may take a different line given higher rate of legal suits.

Date: Mon, 23 Mar 1998 22:35:52 -0500
From: Carl McNeely <mcneely@sover.net>
Subject: Lens changes in association with quetiapine

For those with questions regarding the issue of quetiapine (Seroquel) and reported ocular changes, please consider the following:

Ocular Assessments

There is a warning on the package insert about cataracts, and a recommendation that patients on quetiapine have baseline and follow-up eye exams. This warning is based on the fact that cataracts were noted in dog studies of quetiapine. However, this finding was not replicated in long-term monkey studies, which showed no evidence of cataract (data on file, Zeneca Pharmaceuticals). Furthermore, there were no differences in ocular changes between quetiapine and haloperidol patients in a long-term clinical trial. Because the dog study was an isolated finding, I believe that this risk, if there is any, is not any different from other commonly used psychotropic medications such as chlorpromazine or carbamazepine.

What should we make of this? First of all, it is good to know the evidence behind the warning so it won't come as a surprise to patients reading the package insert. In terms of implementing the recommendations, I plan to obtain an eye exam only after I have put the patient on quetiapine and have established that the patient has responded to quetiapine. Then, if the patient is at high risk for cataracts (e.g., elderly or diabetic), I will insist on baseline and follow-up eye exams. For other patients, I will discuss the labeling warning and make my recommendations on a case-by-case basis.

Weiden, PJ. (1997) Quetiapine (Seroquel): A new "Atypical" Antipsychotic. J Prac Psych and Behav Hlth, Nov: 368-374.

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