This information is intended for use by health professionals

1. Name of the medicinal product

Dorzolamide 20mg/ml Eye drops, solution

2. Qualitative and quantitative composition

Each ml contains 20 mg dorzolamide (as 22.3 mg of dorzolamide hydrochloride).

Excipients: Each ml of eye drops solution contains 0.075mg Benzalkonium Chloride.

For a full list of excipients, see section 6.1.

3. Pharmaceutical form

Eye drops, solution.

Isotonic, buffered, slightly viscous, clear, colorless aqueous solution.

4. Clinical particulars
4.1 Therapeutic indications

Dorzolamide is indicated:

• as adjunctive therapy to beta-blockers,

• as monotherapy in patients unresponsive to beta-blockers or in whom beta-blockers are contraindicated,

in the treatment of elevated intra-ocular pressure in:

• ocular hypertension,

• open-angle glaucoma,

• pseudo-exfoliative glaucoma.

4.2 Posology and method of administration

When used as monotherapy, the dose is one drop of dorzolamide in the conjunctival sac of the affected eye(s), three times daily.

When used as adjunctive therapy with an ophthalmic beta-blocker, the dose is one drop of dorzolamide in the conjunctival sac of the affected eye(s), two times daily.

When substituting dorzolamide for another ophthalmic anti-glaucoma agent, discontinue the other agent after proper dosing on one day, and start dorzolamide on the next day.

If more than one topical ophthalmic drug is being used, the drugs should be administered at least ten minutes apart.

Patients should be instructed to wash their hands before use and avoid allowing the tip of the dispensing container to contact the eye or surrounding structures.

Patients should also be instructed that ocular solutions, if handled improperly, can become contaminated by common bacteria known to cause ocular infections. Serious damage to the eye and subsequent loss of vision may result from using contaminated solutions.

Patients should be informed of the correct handling of the ophthalmic dispensers.

Usage instructions:

1. Before using the medication for the first time, be sure that the tamper-proof seal on the bottle neck is unbroken. A gap between the bottle and the cap is normal for an unopened bottle.

2. Take off the cap of the bottle.

3. Tilt your head back and gently pull your lower eyelid down to form a small pocket between your eyelid and your eye.

4. Invert the bottle, and squeeze it until a single drop is dispensed into the eye as directed by your doctor. DO NOT TOUCH YOUR EYE OR EYELID WITH THE DROPPER TIP.

5. Repeat steps 3 & 4 with the other eye if instructed to do so by your doctor.

6. Put the cap back on and close the bottle straight after you have used it.

Paediatric population:

Limited clinical data in paediatric patients with administration of dorzolamide three times a day are available. (For information regarding paediatric dosing see section 5.1).

4.3 Contraindications

Hypersensitivity to the active substance or to any of the excipients.

Dorzolamide has not been studied in patients with severe renal impairment (creatine clearance < 30 ml/min) or with hyperchloraemic acidosis. Because dorzolamide and its metabolites are excreted predominantly by the kidney, dorzolamide is therefore contraindicated in such patients.

4.4 Special warnings and precautions for use

Dorzolamide has not been studied in patients with hepatic impairment and should therefore be used with caution in such patients.

The management of patients with acute angle-closure glaucoma requires therapeutic interventions in addition to ocular hypotensive agents. Dorzolamide has not been studied in patients with acute angle-closure glaucoma.

Dorzolamide is a sulphonamide and although administered topically, is absorbed systemically. Therefore the same types of adverse reactions that are attributable to sulphonamides may occur with topical administration. If signs of serious reactions of hypersensitivity occur, discontinue the use of this preparation.

Therapy with oral carbonic anhydrase inhibitors has been associated with urolithiasis as a result of acid-base disturbances, especially in patients with a prior history of renal calculi. Although no acid-base disturbances have been observed with dorzolamide, urolithiasis has been reported infrequently. Because dorzolamide is a topical carbonic anhydrase inhibitor that is absorbed systemically, patients with a prior history of renal calculi may be at increased risk of urolithiasis while using dorzolamide.

If allergic reactions (e.g. conjunctivitis and eyelid reactions) are observed, discontinuation of treatment should be considered.

There is a potential for an additive effect on the known systemic effects of carbonic anhydrase inhibition in patients receiving an oral carbonic anhydrase inhibitor and dorzolamide. The concomitant administration of dorzolamide and oral carbonic anhydrase inhibitors is not recommended.

Corneal oedemas and irreversible corneal decompensations have been reported in patients with pre-existing chronic corneal defects and/or a history of intra-ocular surgery while using Dorzolamide. Topical dorzolamide should be used with caution in such patients.

Choroidal detachment concomitant with ocular hypotony have been reported after filtration procedures with administration of aqueous suppressant therapies.

Dorzolamide contains the preservative benzalkonium chloride, which may cause eye irritation. Benzalkonium chloride is known to discolour soft contact lenses.

Avoid contact with soft contact lenses. Remove contact lenses prior to application and wait at least 15 minutes before reinsertion.

Paediatric Population:

Dorzolamide has not been studied in patients less than 36 weeks gestational age and less than 1 week of age. Patients with significant renal tubular immaturity should only receive dorzolamide after careful consideration of the risk benefit balance because of the possible risk of metabolic acidosis.

4.5 Interaction with other medicinal products and other forms of interaction

No specific drug interaction studies have been performed.

In clinical studies, dorzolamide was used concomitantly with the following medications without evidence of adverse interactions: timolol ophthalmic solution, betaxolol ophthalmic solution and systemic medications, including ACE-inhibitors, calcium-channel blockers, diuretics, non-steroidal anti-inflammatory drugs including aspirin, and hormones (e.g. oestrogen, insulin, thyroxine).

Association between dorzolamide and miotics and adrenergic agonists has not been fully evaluated during glaucoma therapy.

4.6 Pregnancy and lactation


Dorzolamide should not be used during pregnancy.

No adequate clinical data in exposed pregnancies are available. In rabbits, dorzolamide produced teratogenic effects at maternotoxic doses (See Section 5.3)


It is not known whether dorzolamide is excreted in human milk. In lactating rats, decreases in the body weight gain of offspring were observed. Dorzolamide should not be used during lactation.If treatment with dorzolamide is required, then lactation is not recommended.

4.7 Effects on ability to drive and use machines

Possible side effects such as dizziness and visual disturbances may affect the ability to drive and use machines.

4.8 Undesirable effects

Dorzolamide was evaluated in more than 1400 individuals in controlled and uncontrolled clinical studies. In long term studies of 1108 patients treated with Dorzolamide as monotherapy or as adjunctive therapy with an ophthalmic beta-blocker, the most frequent cause of discontinuation (approximately 3%) from treatment with Dorzolamide was drug-related ocular adverse reactions , primarily conjunctivitis and lid reactions.

The following adverse reactions have been reported either during clinical trials or during post-marketing experience.

The frequency of adverse reactions listed below is defined using the following convention:

Very Common: (≥1/10);

Common: (≥1/100 to <1/10);

Uncommon: (≥1/1,000 to <1/100);

Rare: (≥1/10,000 to <1/1,000).

Very rare (<1/10,000)

Not known (cannot be estimated from the available data).

Within each frequency grouping, undesirable effects are presented in order of decreasing seriousness.

Nervous system and psychiatric disorders:




dizziness, paraesthesia

Eye disorders:

Very Common:

burning and stinging


superficial punctate keratitis, conjunctivitis, tearing, blurred vision, eyelid inflammation, eye itching, eyelid irritation




corneal oedema, choroidal detachment following filtration surgery, ocular hypotony, irritation including redness, pain, eyelid crusting, transient myopia (which resolved upon discontinuation of therapy)

Respiratory, thoracic, and mediastinal disorders:



Gastrointestinal disorders:


nausea, bitter taste


throat irritation, dry mouth

Renal disorders:



Skin and subcutaneous tissue disorders:


contact dermatitis

General disorders and administration site conditions:




Hypersensitivity: systemic allergic reactions including angioedema, urticaria and pruritus, rash, shortness of breath, rarely bronchospasm and signs and symptoms of local reactions (palpebral reactions)

Laboratory findings:

Dorzolamide was not associated with clinically meaningful electrolyte disturbances.

Paediatric population:

See 5.1.

4.9 Overdose

Only limited information is available with regard to human overdosage by accidental or deliberate ingestion of dorzolamide hydrochloride. The following have been reported with oral ingestion: somnolence; topical application: nausea, dizziness, headache, fatigue, abnormal dreams, and dysphagia.

Treatment should be symptomatic and supportive. Electrolyte imbalance, development of an acidotic state, and possible central nervous system effects may occur. Serum electrolyte levels (particularly potassium) and blood pH levels should be monitored.

5. Pharmacological properties
5.1 Pharmacodynamic properties

Pharmacotherapeutic group: Carbonic Anhydrase Inhibitor, ATC code: S 01 EC 03

Mechanism of action

Carbonic anhydrase (CA) is an enzyme found in many tissues of the body including the eye. In humans, carbonic anhydrase exists as a number of isoenzymes, the most active being carbonic anhydrase II (CA-II) found primarily in red blood cells (RBCs) but also in other tissues. Inhibition of carbonic anhydrase in the ciliary processes of the eye decreases aqueous humor secretion. The result is a reduction in intra-ocular pressure (IOP).

Dorzolamide contains dorzolamide hydrochloride, a potent inhibitor of human carbonic anhydrase II. Following topical ocular administration, dorzolamide reduces elevated intra-ocular pressure, whether or not associated with glaucoma. Elevated intra-ocular pressure is a major risk factor in the pathogenesis of optic nerve damage and visual-field loss. Dorzolamide does not cause pupillary constriction and reduces intra-ocular pressure without side effects such as night blindness, accommodative spasm. Dorzolamide has minimal or no effect on pulse rate or blood pressure.

Topically applied beta-adrenergic blocking agents also reduce IOP by decreasing aqueous humor secretion but by a different mechanism of action. Studies have shown that when dorzolamide is added to a topical beta-blocker, additional reduction in IOP is observed; this finding is consistent with the reported additive effects of beta-blockers and oral carbonic anhydrase inhibitors.

Pharmacodynamic effects

Clinical effects:

Adult Patients

In patients with glaucoma or ocular hypertension, the efficacy of dorzolamide given t.i.d.. as monotherapy (baseline IOP ≥ 23 mmHg) or given b.i.d.. as adjunctive therapy while receiving ophthalmic beta-blockers (baseline IOP ≥ 22 mmHg) was demonstrated in large-scale clinical studies of up to one- year duration. The IOP-lowering effect of dorzolamide as monotherapy and as adjunctive therapy was demonstrated throughout the day and this effect was maintained during long-term administration. Efficacy during long-term monotherapy was similar to betaxolol and slightly less than timolol. When used as adjunctive therapy to ophthalmic beta-blockers, dorzolamide demonstrated additional IOP lowering similar to pilocarpine 2% q.i.d..

Paediatric Population

A 3-month, double-masked, active-treatment controlled, multicentre study was undertaken in 184 (122 for dorzolamide) paediatric patients from 1 week of age to <6 years of age with glaucoma or elevated intraocular pressure (baseline IOP GREATER-THAN OR EQUAL TO (8805)22 mmHg) to assess the safety of Dorzolamide when administered topically t.i.d. (three times a day). Approximately half the patients in both treatment groups were diagnosed with congenital glaucoma; other common aetiologies were Sturge Weber syndrome, iridocorneal mesenchymal dysgenesis, aphakic patients. The distribution by age and treatments in the monotherapy phase was as follows:

Dorzolamide 2%


Age cohort < 2 years


Age range: 1 to 23 months

Timolol GS 0.25% N=27

Age range: 0.25 to 22 months

Age cohort GREATER-THAN OR EQUAL TO (8805)2 - < 6 years


Age range: 2 to 6 years

Timolol 0.50% N=35

Age range: 2 to 6 years

Across both age cohorts approximately 70 patients received treatment for at least 61 days and approximately 50 patients received 81-100 days of treatment.

If IOP was inadequately controlled on dorzolamide or timolol gel-forming solution monotherapy, a change was made to open-label therapy according to the following: 30 patients <2 years were switched to concomitant therapy with timolol gel-forming solution 0.25% daily and dorzolamide 2% t.i.d.; 30 patients GREATER-THAN OR EQUAL TO (8805)2 years were switched to 2% dorzolamide/0.5% timolol fixed combination b.i.d (twice a day).

Overall, this study did not reveal additional safety concerns in paediatric patients: approximately 26% (20% in dorzolamide monotherapy) of paediatric patients were observed to experience drug related adverse affects, the majority of which were local, non-serious ocular effects such as ocular burning and stinging, injection and eye pain. A small percentage <4% was observed to have corneal oedema or haze. Local reactions appeared similar in frequency to comparator. In post marketing data, metabolic acidosis in the very young particularly with renal immaturity/impairment has been reported.

Efficacy results in paediatric patients suggest that the mean IOP decrease observed in the dorzolamide group was comparable to the mean IOP decrease observed in the timolol group even if a slight numeric advantage was observed for timolol.

Longer-term efficacy studies (>12 weeks) are not available.

5.2 Pharmacokinetic properties

Unlike oral carbonic anhydrase inhibitors, topical administration of dorzolamide hydrochloride allows for the drug to exert its effects directly in the eye at substantially lower doses and therefore with less systemic exposure. In clinical trials, this resulted in a reduction in IOP without the acid-base disturbances or alterations in electrolytes characteristic of oral carbonic anhydrase inhibitors.

When topically applied, dorzolamide reaches the systemic circulation. To assess the potential for systemic carbonic anhydrase inhibition following topical administration, drug and metabolite concentrations in RBCs and plasma and carbonic anhydrase inhibition in RBCs were measured. Dorzolamide accumulates in RBCs during chronic dosing as a result of selective binding to CA-II while extremely low concentrations of free drug in plasma are maintained. The parent drug forms a single N-desethyl metabolite that inhibits CA-II less potently than the parent drug but also inhibits a less active isoenzyme (CA-I). The metabolite also accumulates in RBCs where it binds primarily to CA-I. Dorzolamide binds moderately to plasma proteins (approximately 33%). Dorzolamide is primarily excreted unchanged in the urine; the metabolite is also excreted in urine. After dosing ends, dorzolamide washes out of RBCs non linearly, resulting in a rapid decline of drug concentration initially, followed by a slower elimination phase with a half-life of about four months.

When dorzolamide was given orally to simulate the maximum systemic exposure after long-term topical ocular administration, steady state was reached within 13 weeks. At steady state, there was virtually no free drug or metabolite in plasma; CA inhibition in RBCs was less than that anticipated to be necessary for a pharmacological effect on renal function or respiration. Similar pharmacokinetic results were observed after chronic, topical administration of dorzolamide.

However, some elderly patients with renal impairment (estimated CrCl 30-60 ml/min) had higher metabolite concentrations in RBCs, but no meaningful differences in carbonic anhydrase inhibition, and no clinically significant systemic side effects were directly attributable to this finding.

5.3 Preclinical safety data

The main findings in animal studies with dorzolamide hydrochloride administered orally were related to the pharmacological effects of systemic carbonic anhydrase inhibition. Some of these findings were species-specific and/or were a result of metabolic acidosis. In rabbits given maternotoxic doses associated with metabolic acidosis, malformations of the vertebral bodies were observed.

In clinical studies, patients did not develop signs of metabolic acidosis or serum electrolyte changes that are indicative of systemic CA inhibition. Therefore, it is not expected that the effects noted in animal studies would be observed in patients receiving therapeutic doses of dorzolamide.

6. Pharmaceutical particulars
6.1 List of excipients


Hydroxy Ethyl Cellulose

Benzalkonium Chloride

Sodium Citrate

Sodium Hydroxide for pH adjustment

Water for injections

6.2 Incompatibilities

Not Applicable.

6.3 Shelf life

2 years.

After first opening: 28 days.

6.4 Special precautions for storage

Keep the bottle in the outer carton in order to protect from light.

Store below 30°C.

6.5 Nature and contents of container

White opaque polyethylene medium density ophthalmic bottle with a sealed dropper tip and a two-piece screw cap assembly. Each bottle contains 5ml of solution.

Dorzolamide is available in the following pack sizes:

1 bottle, 3 bottles and 6 bottles.

Not all pack sizes may be marketed.

6.6 Special precautions for disposal and other handling

No special requirements.

7. Marketing authorisation holder

Pharmathen S.A.

6, Dervenakion str.,

153 51 Pallini Attiki,


8. Marketing authorisation number(s)

PL 17277/0128

9. Date of first authorisation/renewal of the authorisation


10. Date of revision of the text


Distributors in the UK

Beacon Pharmaceuticals Ltd. 85, High St, Tunbridge Wells, TN1 1YG, UK

Tel: 01892-600930