Ocular toxicity treatment

Barrett NA, Solano T. Quinine ocular toxicity treatment of blindness using therapy for vasospasm. Anaesth Intensive Care 2002 30(2) 234-5. 

Pavlidis NA, Petris C, Briassoulis E, Klouvas G, Psilas C, Rempapis J, Petroutsos G (1992) Clear evidence thatlong-term, low-dose tamoxifen treatment can induce ocular toxicity a prospective study of 63 patients. Cancer 69(12) 2961-2964... 

Its most important adverse effects are visual disturbances. This ocular toxicity is dose dependent and has an incidence of lower than 1 % at low doses but can reach 5% at high dose regimens. Ocular toxicity manifests itself as retrobulbar neuritis usually after the second month of use. If therapy is discontinued immediately it is mostly reversible but not always. During the treatment visual function should periodically be tested. Age under 8 years is a relative contraindication as visual symptoms are difficult to monitor. 

Intravenous cidofovir is effective for the treatment of CMV retinitis and is used experimentally to treat adenovirus infections. Intravenous cidofovir must be administered with high-dose probenecid (2 g at 3 hours before the infusion and 1 g at 2 and 8 hours after), which blocks active tubular secretion and decreases nephrotoxicity. Cidofovir dosage must be adjusted for alterations in the calculated creatinine clearance or for the presence of urine protein before each infusion, and aggressive adjunctive hydration is required. Initiation of cidofovir therapy is contraindicated in patients with existing renal insufficiency. Direct intravitreal administration of cidofovir is not recommended because of ocular toxicity. 

The use of tamoxifen to prevent breast cancer has been reviewed (8). The merits of using tamoxifen to prevent mammary carcinoma in women who have never had the disease but are believed to be at high risk have been disputed (9), but it is clear that it would involve very long treatment and that one s view of the adverse effects might need to be revised for this class of users. The available data after 5,10, and 15 years of follow up confirmed an increase in the incidence of endometrial cancer and of thromboembolic complications and suggested ocular toxicity, but these effects were not common and should be more than balanced by the reduced risk of coronary heart disease and osteoporosis (8). 

Visual symptoms may occur as soon as 1 day after drug administration, but often occur within 2 weeks of initial therapy. Occasionally, ocular toxicity does not appear imtil after several years of treatment. Once the serum level is decreased or digitalis therapy is discontinued, however, visual symptoms quickly subside, usually within several weeks. 

Ocular disturbances due to ethambutol are dose-related. Dosages not over 25 mg/kg/day during the first 2 months of treatment and 15 mg/kg/day thereafter are generally accepted as adequate (7). At a dosage of 15 mg/kg/day, which should be regarded as a maximum for maintenance therapy, ocular toxicity developed in only 1.6% of patients (8). Advanced age (9), renal insufficiency, and diabetes can enhance ocular damage. 

Ocular toxicity due to ethambutol is dose-dependent and is usually reversible when the drug is discontinued. Thiamine is not protective. Periodic testing of visual acuity is advisable during treatment. Ethambutol is relatively contraindicated in children too young for assessment of their visual acuity and red-green color discrimination. The answer is (C). 

Chloroquine and hydroxychloroquine belonging to the class of 4-amino-quinoline anthmalarials are being used in clinical practice in the eure and treatment of rheumatoid arthritis sinee 1957. However, the two important disadvantageous faetors, namely slow onset of therapeutie effeet and significant ocular toxicity seemed to have shadowed the elinieal supremacy of these drugs. 

All were double-blind controlled evaluations and established iprindole as at least as effective as imipramine, and one study [195] included an examination of the doctor-patient interaction as a factor in such work (a similar discussion was felt necessary, as noted above [179] in the evaluation of oxpertine). In only two [192, 194] of the above reports is it possible to estimate the frequency and severity of anticholinergic side effects, thou in the one case [192] the care taken in the experimental design and the number of patients observed leaves little doubt that the dry mouth, constipation, etc. characteristic of imipramine therapy is either greatly reduced or even absent during iprindole treatment. This point is confirmed in an extension of this team s work to include a 12 month toxicity study [197] which, in addition, failed to produce evidence of haemopoitic, hepatic, cardiac, ocular or renal damage. Similar results followed other work. 

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