Timolol

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Timolol
File:Timolol Structural Formulae.png
Systematic (IUPAC) name
(S)-1-(tert-butylamino)-3-[(4-morpholin-4-yl-1,2,5-thiadiazol-3-yl)oxy]propan-2-ol
Clinical data
Pregnancy
category
  • AU: C
  • US: C (Risk not ruled out)
Routes of
administration
oral, Ophthalmic
Legal status
Legal status
  • ℞ (Prescription only)
Pharmacokinetic data
Bioavailability 60%
Metabolism Hepatic: 80%
Biological half-life 2.5-5 hours
Excretion Renal
Identifiers
CAS Number 26839-75-8
ATC code C07AA06 (WHO)
PubChem CID 5478
IUPHAR/BPS 565
DrugBank APRD00229
Chemical data
Formula C13H24N4O3S
Molar mass 316.421 g/mol[[Script error: No such module "String".]]
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Timolol maleate is a non-selective beta-adrenergic receptor blocker. In its oral form (Blocadren), it is used to treat high blood pressure and prevent heart attacks, and occasionally to prevent migraine headaches. In its ophthalmic form (brand names Timoptol in Italy; Timoptic), it is used to treat open-angle and occasionally secondary glaucoma by reducing aqueous humour production through blockage of the beta receptors on the ciliary epithelium. The pharmacological mechanism by which it actually does this is still unknown.

Side effects

The most serious possible side effects include cardiac arrhythmias and severe bronchospasms. Timolol can also lead to fainting, congestive heart failure, depression, confusion, worsening of Raynaud's syndrome and impotence.

Usual dosage

  • Children and Adults: Ophthalmic: Initial: 0.25% solution, instill 1 drop twice daily; increase to 0.5% solution if response not adequate; decrease to 1 drop/day if *controlled; do not exceed 1 drop twice daily of 0.5% solution Adults: Oral:
  • Hypertension: Initial: 10 mg twice daily, increase gradually every 7 days, usual dosage: 20–40 mg/day in 2 divided doses; maximum: 60 mg/day
  • Prevention of myocardial infarction: 10 mg twice daily initiated within 1–4 weeks after infarction
  • Migraine headache: Initial: 10 mg twice daily, increase to maximum of 30 mg/day

Formulations

  • Gel-forming solution, ophthalmic, as maleate (Timoptic-XE): 0.25% (2.5 mL, 5 mL); 0.5% (2.5 mL, 5 mL)
  • Solution, ophthalmic, as hemihydrate (Betimol): 0.25% (5 mL, 10 mL, 15 mL); 0.5% (5 mL, 10 mL, 15 mL) [contains benzalkonium chloride]
  • Solution, ophthalmic, as maleate: 0.25% (5 mL, 10 mL, 15 mL); 0.5% (5 mL, 10 mL, 15 mL) [contains benzalkonium chloride]
  • Timoptic: 0.25% (5 mL, 10 mL); 0.5% (5 mL, 10 mL) [contains benzalkonium chloride]
  • Solution, ophthalmic, as maleate [preservative free] (Timoptic OcuDose): 0.25% (0.2 mL);0.5% (0.2 mL) [single use]
  • Tablet, as maleate (Blocadren): 5 mg, 10 mg, 20 mg

For ophthalmic use, timolol is also available combined with other medications:

Brand names

  • In Canada: Apo-Timol, Apo-Timop, Gen-Timolol, Nu-Timolol, Phoxal-timolol, PMS-Timolol, Tim-AK, Timoptic, Timoptic-XE.
  • In the United States: Betimol, Blocadren, Istalol, Timoptic, Timoptic-XE, Timoptic OcuDose.

Chemical synthesis

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http://dx.doi.org/10.1021/jo00881a011


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