Carbonic Anhydrase Inhibitors


Brinzolamide (Azopt®), Dorzolamide (Trusopt®)

  Issues for Surgery


For primary open-angle glaucoma (topical) – increased risk of deterioration in eyesight if omitted for a prolonged period.


  Advice in the Perioperative period


Elective and Emergency Surgery

Continue including the following combination products (unless the patient is undergoing ophthalmology surgery and the Ophthalmologist requests for them to be withheld): -

Confirm with patient if drops are prescribed for left eye, right eye or both eyes.Encourage correct application technique to reduce systemic absorption (see Further Information)

Post-operative Advice

Restart post-operatively when next dose is due (unless the patient has undergone ophthalmology surgery and the Ophthalmologist requests for them to be withheld).

   Interaction(s) with Common Anaesthetic Agents


Systemic absorption can follow topical administration of carbonic anhydrase inhibitors so interactions are possible 1 but none are expected 1, 2, 3, 4.


For combination products containing beta-blockers
Systemic absorption can follow topical application of beta-blockers to the eyes 1 – the advice and cautions as listed for systemic beta-blockers should be considered (see Beta-adrenoceptor Blockers (Beta-Blockers) (Systemic and Topical) monograph). 

For combination products containing alpha2-adrenoceptor agonists
There is potential for systemic absorption, see alpha2-adrenoceptor agonists monograph for interactions.

  Interaction(s) with other Common Medicines used in the Perioperative Period


Systemic absorption can follow topical administration of carbonic anhydrase inhibitors so interactions are possible 1 but none have been noted 1, 2, 3, 4. Brinzolamide is partially metabolised by CYP3A4 so the manufacturers advise caution with the concomitant use of CYP3A4 inhibitors (e.g. clarithromycin) although they note accumulation of brinzolamide is unlikely due to other elimination pathways 3, therefore this would not be expected to be clinically significant.


For combination products containing beta-blockers
Systemic absorption can follow topical application of beta-blockers to the eyes1 – the advice and cautions as listed for systemic beta-blockers should be considered (see Beta-adrenoceptor Blockers (Beta-Blockers) (Systemic and Topical)monograph). 

For combination products containing alpha2-adrenoceptor agonists
There is potential for systemic absorption, see alpha2-adrenoceptor agonists monograph for interactions..

  Further Information


Systemic Absorption
Nasolacrimal occlusion or gently closing the eyelid is recommended following ocular administration of any medication to reduce systemic absorption 3, 4.

  References


  1. Joint Formulary Committee. British National Formulary (online) London: BMJ Group and Pharmaceutical Press. http://www.medicinescomplete.com [Accessed on 5th February 2021]
  2. Baxter K, Preston CL (eds), Stockley’s Drug Interactions (online) London: Pharmaceutical Press. http://www.medicinescomplete.com [Accessed on 5th February 2021]
  3. Summary of Product Characteristics – Azopt® (brinzolamide) eye drops. Novartis Pharmaceuticals UK Ltd. Accessed via www.medicines.org.uk 05/02/2021 [date of revision of the text June 2018]
  4. Summary of Product Characteristics – Trusopt® (dorzolamide) 20 mg/ml Eye drops, solution. Santen UK Ltd. Accessed via www.medicines.org.uk 05/02/2021 [date of revision of the text November 2020]