Carbachol is a cholinomimetic (cholinergic) gent that lowers the intraocular pressure in patients with open angle glaucoma. It is also used during eye surgery for miosis.

Carbachol Dose in Adults

Dose in the treatment of Glaucoma:

• Instill the ophthalmic solution 1-2 drops thrice daily.

Dose in the treatment of Ophthalmic surgery ( miosis):

•  Inject 0.5 mL into anterior chamber before or after securing the sutures during intraocular surgery.

Carbachol Dose in Childrens

 The efficacy and safety of carbachol in children has not been established.

Pregnancy Risk Factor C

• It should not be used in pregnant women and is not recommended for use.

Carbachol use during breastfeeding:

• Breastfeeding women should not use it as the excretion into breastmilk is not well studied.

Carbachol Dose in Renal Disease:

Dose adjustment has not been recommended in the manufacturer's labeling in patients with renal disease.

Carbachol Dose in Liver Disease:

Dose adjustment has not been recommended in the manufacturer's labeling in patients with liver disease.

Common side Effects Of Carbachol Inlude:

• Cardiovascular:
  • Flushing
• Central nervous system:
  • Headache
• Dermatologic:
  • Diaphoresis
• Gastrointestinal:
  • Abdominal cramps
  • epigastric distress
• Genitourinary:
  • Bladder spasm
• Ophthalmic:
  • Corneal opacity
  • Epithelial keratopathy
  • Iritis
  • Retinal detachment

Contraindication to Carbachol include:

• Allergy to carbachol, or any other component of the formulation
• Acute iritis
• Acute inflammation disease of the eye, especially the anterior chamber.

Warnings and Precautions

• Asthma
  • Patients with asthma should be cautious when using the drug.
• Corneal abrasion:
  • Patients suffering from corneal abrasions or an inflammatory condition of their eyes should be cautious.
• Gastrointestinal Disease:
  • Patients with peptic ulcer disease and gastrointestinal spasm should be cautious.

• Heart failure:
  • It may cause heart failure to worsen because of its cholinergic effects.
  • Patients with acute heart failure should use the drug with caution.

• Hyperthyroidism:
  • Patients with thyroid problems should exercise caution.
• Parkinson disease
  • It could alter Parkinson's symptoms. Please be cautious.
• Occlusion of the urinary tract:
  • It may cause urinary retention due to its cholinergic effects.

• General anesthesia
  • Before general anesthesia is induction, the anesthetist must be informed.

• Latex
  • Latex is used to package the injection. Patients with latex allergy should not use it.

Carbachol: Drug Interaction

Note: Drug Interaction Categories:

• Risk Factor C: Monitor When Using Combination
• Risk Factor D: Consider Treatment Modification
• Risk Factor X: Avoid Concomitant Use

Monitoring parameters:

• Monitor intraocular pressure. 

How to administer Carbachol?

• Ophthalmic instillation:
  • Instill the prescribed amount and apply pressure on the lacrimal sac for 1 - 2 minutes with the fingers. Remove the excess medicine around the eye with a tissue.
• Intraocular administration:
  • Using a sterile technique, inject the required amount (but not more than 0.5 ml) into the anterior chamber gently parallel to the iris face and tangential to the pupil border before the surgery or after securing the sutures.

Mechanism of action of Carbachol:

• It is a synthetic, direct-acting cholinergic agent (cholinomimetic).
• It causes miosis (constricts the pupils) by stimulating the muscarinic receptors within the eye.

Miosis

• It takes between 10 and 20 minutes, and intraocular pressure drops for 4 to 8 hours.

Carbachol International Brands:

• Carbachol
• Carbal
• Doryl
• Isopto Carbachol
• Isopto Karbakolin
• Isopto-Carbachol
• Karbakolin
• Isopto
• Miostat
• Mioticol
• Mystop

Carbachol brands in Pakistan: