Meds and you

27 September 2013

Dorzolamide and timolol

The combination of dorzolamide and timolol is the active ingredient of Cosopt ophthalmic solution (Nappi code: 860379-019).

0

The combination of dorzolamide and timolol is the active ingredient of Cosopt ophthalmic solution (Nappi code: 860379-019).

General information

The combination of dorzolamide and timolol is an anti-glaucoma preparation. Anti-glaucoma preparations are drugs that reduce pressure inside the eye.

In South Africa the combination of travoprost and timolol is registered for the reduction of elevated intra-ocular pressure in ocular hypertension, and also for the treatment of various types of glaucoma.

For this medication to be effective, it has to be taken regularly, even if you do not notice an immediate effect.

It is recommended that after administering these eye drops, you press on the tear duct (at the corner of the eye closest to your nose), or gently close your eyes for about three minutes. This process, nasolacrimal occlusion, may possibly reduce systemic side effects and also increase the local effect of the medication in the eye.

It should be noted that because this drug may cause visual disturbances and/or dizziness, driving and any hazardous tasks should be avoided, until you know how this medication affects you.

The combination of dorzolamide and timolol ophthalmic drops should not be used if you have soft contact lenses in your eyes.

How does the combination of dorzolamide and timolol work?
Bicarbonate is required for the production of the watery fluid inside the eye. Dorzolamide blocks the production of bicarbonate, and as a result the production of watery fluid within the eye is also reduced. As a result the aqueous humour filling the eye is decreased, and subsequently the intra-ocular pressure within the eye is reduced.

Timolol causes blood vessels in the eye to narrow. By narrowing these blood vessels, less fluid passes through the blood vessel into the eyeball, thereby reducing pressure within the eye further.

Fast facts
Drug schedule: schedule 3
Available as: the combination of dorzolamide and timolol is available as eye drops.
What does it do? This combination reduces pressure within the eye.
Overdose risk: low
Dependence risk: low
Is the combination of dorzolamide and timolol available as a generic? no
Is this combination available on prescription only? yes

User information
Onset of effect: within 30 minutes
Duration of action: up to 8 hours
Stopping this medicine: do not stop taking this drug without consulting your doctor.
Prolonged use: Regular ophthalmic examination is advised with long-term use.

Special precautions
Consult your doctor before using this drug if:

  • you are allergic to sulphonamides such as the antibiotic sulphametoxazole
  • you have liver disease
  • you have been diagnosed with high levels of acid in the blood, a condition known as acidosis
  • you have kidney disease
  • you are pregnant, or plan to fall pregnant
  • you have or had heart disease
  • you have asthma
  • you have chronic bronchitis
  • you have diabetes
  • you have a slow heart rate (<50 beats per minute)
  • you are taking any other medication

Pregnancy: avoid. Potential risk to the foetus has been reported. Consult your doctor before use, or if you are planning to fall pregnant.
Breastfeeding: avoid. It is unknown how this medication may affect your baby. Consult your doctor before use.
Porphyria: avoid. This medication may cause serious adverse effects. Consult your doctor before use.
Infants and children: this medication is not intended for use in children.
The elderly: caution is advised in the elderly as side effects are more likely to occur.
Driving and hazardous work: caution is advised as use of this medication may lead to dizziness, light-headedness and/or sedation. Avoid such activities until you know how this medication affects you.
Alcohol: no special precautions need to be taken.

Possible side effects

Side effect

Frequency

Consult your doctor

Common

Rare

Only if severe

In all cases

Burning

x


X


stinging

x


X


tingling sensation

x


X


local irritation

x


x


blurred vision

x


x


watery eyes


x

x


dry eyes

x


x


photosensitisation


x

x


bitter taste in mouth

x


x


inflamed/ sore eyes


x


x

headache


x

x


nausea


x

x


eyelid inflammation/oedema


x


x

skin rash


x


x

fever


x


x

sore throat


x


x

difficulty breathing


x


x

corneal disorders


x


x

Interactions

Drug interactions

acetazolamide

risk of added systemic toxicity

topical beta-blockers

additive effect in reducing intra-ocular pressure

aspirin

risk of the combination of dorzolamide and timolol toxicity

reserpine

lowering of blood pressure, slow heart rate and dizziness may occur

digoxin

increased side effects of digoxin

verapamil

increased side effects of verapamil

oral beta-receptor blockers

increased risk of side effects with both drugs

Overdose action
A small overdose is no cause for concern. In case of intentional large overdose, seek emergency medical attention.

Recommended dosage
Adults: 1 drop 2 daily in the affected eye


This material is not intended to substitute medical advice, but is for informational purposes only.
Please consult a physician for specific treatment and recommendations.

 
 

Read Health24’s Comments Policy

Comment on this story
0 comments
Comments have been closed for this article.