Glaucoma, drugs used

TABLE 58-3. Topical Drugs Used in the Treatment of Open-Angle Glaucoma... 

Acetazolamide is a carbonic anhydrase inhibitor that reduces aqueous humour production and is therefore indicated in glaucoma to reduce the intraocular pressure. Salbutamol is a selective, short-acting beta2-agonist used as a bronchodilator in asthma. Tolbutamide is a short-acting sulphonylurea used in type 2 (non-insulin dependent) diabetes mellitus. Chlorpromazine is an aliphatic neuroleptic antipsychotic drug used in schizophrenia. Zafirlukast is a leukotriene-receptor antagonist that is indicated in the prophylaxis of asthma but should not be used to relieve acute severe asthma. 

Dorzolamide (Trusopt) [Carbonic Anhydrase Inhibitor, Sul-fonamide/Glaucoma A9ent] Uses Glaucoma Action Carbonic anhydrase inhibitor Dose 1 gtt in eye(s) tid Caution [C, ] Contra Component sensitivity Disp Soln SE Irritation, bitter taste, punctate k atitis, ocular all gic Rxn EMS t Effects W/ oral carbonic anhydrase inhibitors, salicylates EMS Drug is absorbed systemicaUy OD May cause electrolyte disturbances (K) and acidosis monitor ECG... 

Pilocarpine (P), a drug used in treating glaucoma, can potentially contain its epimer, isopilocarpine (I) as an impurity. In a study it was not possible to completely separate pilocarpine and isopilocarpine by variation of the pH of the running buffer. The optimal pH for separation should be 6.9 where both compounds are ca 50% ionised but even at this pH separation was incomplete.- ... 

Camras CB, Toris CB, Tamesis RR. Efficacy and adverse effects of medications used in the treatment of glaucoma. Drugs Aging 1999,15 377-388. 

Latanoprost is a pro drug used in the treatment of glaucoma. The 15S isomer of the acid is only about 10 % as active as the 15R isomer of the acid. Draw the structural formula of the more active epimer and determine the configuration of the remaining stereogenic units present. 

Pilocarpine is a widely studied peripheral stimulant of the parasympathetic system (101). It is used topically as a myotic to counteract the mydriatic effect of atropine and other parasympatholytic drugs. It has clinical value in the treatment of glaucoma when used as eye drop solutions ranging from 0.5 to 10% in concentration (102). Pilocarpine is reported to stimulate the growth of hair and therefore was employed in hair lotions (1). Internally, it was used as a diaphoretic in the treatment of nephritis (103). 

Q9 Comment on the drug treatments for glaucoma by explaining their mechanism of action. Your answer should include some examples of the drugs used. 

Q10 Comment on the side effects/contraindications associated with drugs used to treat glaucoma. 

Box 10-1 Ocular Hypotensive Drugs Used to Treat Glaucoma... 

From an efficacy point of view, early studies with HEMA based lenses were conducted using pilocarpine, the key available glaucoma drug during that era. Several studies reported improvements in reduction of intraocular pressure and corneal drug flux using... 

Stjernschantz et al. later developed latanoprost [22], which has potent IOP-reducing effects with topical administration once daily in the evening. Compared with a representative (3-blocker, timolol, it demonstrated superior efficacy in clinical studies in reducing IOP by approximately 27-34% from baseline. Latanoprost is the FP receptor agonist most widely used worldwide as an anti-glaucoma drug. 

Vogel R, Strahlman E, Rittenhouse KD. Adverse events associated with commonly used glaucoma drugs. Int Ophthalmol Clin 1999 39 107-124. 

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