A repeated dose-response study of methazolamide in glaucoma

Area of Science:

• Ophthalmology
• Pharmacology

Background:

• Open-angle glaucoma is a leading cause of irreversible blindness.
• Effective management of intraocular pressure (IOP) is crucial for preventing glaucomatous optic neuropathy.
• Carbonic anhydrase inhibitors are a class of drugs used to lower IOP.

Purpose of the Study:

• To evaluate the dose-dependent efficacy of methazolamide in reducing intraocular pressure.
• To compare the IOP-lowering effects of methazolamide with acetazolamide.
• To assess the duration of methazolamide's maximal IOP-lowering effect.

Main Methods:

• Twenty-two patients with open-angle glaucoma received weekly courses of methazolamide at varying dosages (25 mg, 50 mg, 100 mg every eight hours).
• Intraocular pressure and outflow facility were measured.
• Eight patients were subsequently treated with acetazolamide (250 mg four times daily) for one week.

Main Results:

• Mean IOP reductions of 3.3, 4.3, and 5.6 mm Hg were observed at methazolamide dosages of 25 mg, 50 mg, and 100 mg every eight hours, respectively.
• Maximal IOP lowering persisted for 9-10 hours after administration.
• The mean reduction in outflow pressure at 300 mg daily methazolamide was 31%, with significant variability among patients.
• Acetazolamide (250 mg qid) showed an IOP-lowering effect between that of 50 mg and 100 mg methazolamide t.i.d.

Conclusions:

• Methazolamide demonstrates dose-dependent IOP reduction in open-angle glaucoma.
• The drug's efficacy is sustained for a significant duration.
• Individual responses to methazolamide can vary, necessitating careful patient monitoring.
• Methazolamide offers a therapeutic alternative with a different dosing profile compared to acetazolamide.