Glaucoma patients not compliant with their drug therapy: clinical and behavioural aspects

A double-masked study of timolol and pilocarpine combined

In a double-masked, randomized, multicenter study, 25 patients received timolol 0.5%-pilocarpine 2% twice a day, 25 received timolol 0.5%-pilocarpine 4% twice a day, and 25 received pilocarpine 4% four times a day. The combination drugs showed an immediate, significant reduction in intraocular pressure of 7.2 mm Hg (25%) and 10.7 mm Hg (37%), respectively. The lowered intraocular pressure level was maintained throughout the three-week test period. With pilocarpine alone, intraocular pressure was reduced 5.3 mm Hg (19%). The mean intraocular pressure 12 hours after the last dose compared to two hours after the last dose was significantly higher both in patients receiving pilocarpine four times a day and in patients receiving timolol 0.5%-pilocarpine 4% twice a day (5.1 and 3.6 mm Hg, respectively), but not in patients receiving timolol 0.5%-pilocarpine 2% twice a day (2.6 mm Hg).

Compliance with topical pilocarpine treatment

Using an unobtrusive eyedrop medication monitor, we measured compliance with topical pilocarpine treatment in a sample of 184 patients. The eyedrop monitor recorded electronically the date and time of each pilocarpine administration over a four- to six-week period. The subjects administered a mean +/- S.D. of 76.0% +/- 24.3% of the prescribed pilocarpine doses. Eleven patients (6%) took less than one quarter and 28 patients (15.2%) took less than one half of the prescribed administrations. In contrast, when the subjects were interviewed they reported taking a mean +/- S.D. of 97.1% +/- 5.9% of the prescribed pilocarpine doses. As determined by the monitor, 45 patients (24.5%) had at least one day per month with no administrations of pilocarpine; 56 subjects (30.4%) compressed the doses during the daytime hours, leaving an interval between the night dose and the morning dose the next day of 12 hours or more. The rate of compliance was significantly higher (P less than .0001) in the 24-hour period preceding the return appointment than in the entire observation period.

The influence of oxybuprocaine (Novesine) on the intraocular pressure

Patients with raised intraocular pressure often have lower tension during hospital admissions than on out-patient measurement, even though the therapy is the same. A prospective study on 18 volunteers and 10 glaucoma patients was set up to find out whether oxybuprocaine eyedrops or repeated applanation tonometry could have anything to do with this. The tension was measured at least 3 times a day with the non-contact tonometer (NCT). In the case of the volunteers oxybuprocaine was instilled into the eye 3 times a day for one week. In the case of the patients the tension in one eye was measured with the Goldmann tonometer on several days after the application of oxybuprocaine drops. No reduction in intraocular pressure was found during the observation period, nor was there an obvious difference between the test eyes and the control eyes. In hospital, patients had at 11 o'clock in the morning intraocular pressure which was on the average 2.2 +/- 1.5 mmHg lower than that measured at out-patient checks, in spite of receiving the same therapy.

Pilocarpine prodrugs I. Synthesis, physicochemical properties and kinetics of lactonization of pilocarpic acid esters

Various alkyl and aralkyl esters of pilocarpic acid were synthesized and evaluated as prodrug forms for pilocarpine with the purpose of improving the ocular bioavailability of pilocarpine through increased corneal membrane permeability. The esters were found to undergo a quantitative cyclization to pilocarpine in aqueous solution of pH 3.5-10, the rate of cyclization being a function of the polar and steric effects within the alcohol portion of the esters. The rates of lactonization increased proportionally with the hydroxide ion activity over the pH range studied which is in accord with a reaction mechanism involving intramolecular nucleophilic attack of alkoxide ion on the ester carbonyl moiety. At pH 7.4 and 37 degrees C, half-times of lactonization ranging from 30 min (p-chlorobenzyl ester) to 1105 min (n-hexyl ester) were observed for the various esters. The esters are markedly more lipophilic than pilocarpine. The results suggested that the pilocarpic acid esters may be potentially useful prodrugs, especially when further derivatized to give in vitro stable pilocarpic acid diesters.

Facilitating patient compliance in glaucoma therapy

Noncompliance is a major problem in glaucoma therapy. The causes, forms, and sociological variables associated with noncompliance are reviewed. A comprehensive strategy to facilitate the safe and effective use of glaucoma medications is presented and discussed. This strategy combines education about the disease and its treatment, "tailoring" of the therapeutic regimen, training and reinforcement in eyedrop application, cooperation with primary care physicians, alleviating side effects, and improving doctor-patient relationships.

Educating the glaucoma patient

Forty-nine patients with open-angle glaucoma and 32 controls were studied at each of 2 medical centres, one in California and one in England. A 12-point questionnaire was answered before, immediately after, and 6 months after viewing a 6 minute video film about glaucoma. The English glaucoma patients and controls showed lower initial knowledge than their American counterparts. Immediately after the film all groups had substantially improved their knowledge by answering 78-88% of the questions correctly. Recall study showed that both American groups had retained more than their British counterparts and that glaucoma patients retained more knowledge of their disease than did controls. The use of an educational video film in an outpatient setting is a simple and economical method of patient education applicable to both American and British subjects with open-angle glaucoma.

Visual ability and drug regimen: relation to compliance with glaucoma therapy

Compliance with pilocarpine eye drop therapy was studied in relation to different measures of visual ability and different features of the drug regimen. Neither visual ability, nor complexity of the drug regimen nor side effects were significantly related to the patients' compliance with their pilocarpine therapy. Nevertheless, non-compliance was significantly more common among patients who regarded the eye drops as very unpleasant than among patients who did not. This indicates that non-compliance is related to the patient's perception of side effects and/or negative attitudes to the treatment.