Beta-blockers

β BLOCKERS

  1. Timolol ( Adult : 0.5%, Child : 0.25% )
  2. Betaxolol ( 0.25% & 0.5% )
  3. Levabunolol ( 0.5% )
  4. Carteolol ( 1% & 2% )
  5. Metipranolol ( 0.1%, 0.3% 6% )

 

Mechanism of Action:

Mechanism:1

Blocks β2 receptors in ciliary body

(Site of aqueous formation)

↓

Decreased aqueous production

(sympathomimetic action–aqueous production)

↓

Reduced intra ocular pressure (IOP)

Mechanism:2

In juxta canalicular part

↓

Opens trabecular space

↓

Increase aqueous outflow

↓

Decrease IOP

 

 

Duration of action: 12 hours ( TIMOLOL )

Frequency: BDS

INDICATIONS :

  1. Developmental glaucoma
  2. Open Angle Glaucoma: Primary & Secondary
  3. Angle Closure Glaucoma

 

CONTRA-INDICATIONS:

  1. Bronchial ashthma
  2. COPD
  3. Heart Attack
  4. CHF
  5. Cardiomyopathy
  6. Drug allergy
    • Betaxolol, selective β1 adrenergic antagonist, is drug of choice for these patients.

 

ADVANTAGES : (over miotics: pilocarpine)

  1. No change in pupil size – no dimness of vision in dim light & in cataract patients.
  2. No induced myopia
  3. No headache/brow pain
  4. No fluctuation in IOP
  5. ½ daily dose

 

SIDE EFFECTS:

  1. OCULAR:
    • Burning sensation, irritation, dry eye
    • Conjunctival hyperemia
    • Superficial punctuate keratitis
    • Corneal anesthesia
  1. SYSTEMIC:
    • CVS: due to β1 blockade : syncope, bradycardia, arrhythmia, heart failure.
    • RS: due to β2 blockade ( not with Betaxolol ) : bronchospasm, airway obstruction.
    • CNS: depression, anxiety, confusion, disorientation, hallucination.
    • MISCELLANEOUS: nausea, diarrhea, reduced libido, skin rashes, alopecia, exacerbation of myasthenia gravis.

 

FOR TIMOLOL ONLY :

  1. SHORT TERM ESCAPE: marked fall in IOP followed by transient rise with continued moderate fall in IOP.
  2. LONG TERM DRIFT:
  3. LONG TERM SHIFT: