Timolol

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Timolol
Timolol structure.svg
Timolol ball-and-stick.png
Clinical data
Trade names Betimol, others[1]
AHFS/Drugs.com Monograph
MedlinePlus a602022
License data
Pregnancy
category
  • AU: C
  • US: C (Risk not ruled out)
Routes of
administration
By mouth, topical (eye drop)
ATC code
Legal status
Legal status
  • In general: ℞ (Prescription only)
Pharmacokinetic data
Bioavailability 60%
Metabolism Liver (80%)
Biological half-life 2.5–5 hours
Excretion Kidney
Identifiers
CAS Number
PubChem CID
IUPHAR/BPS
DrugBank
ChemSpider
UNII
KEGG
ChEBI
ChEMBL
Chemical and physical data
Formula C13H24N4O3S
Molar mass 316.421 g/mol
3D model (JSmol)
  (verify)

Timolol is a medication used either by mouth or as eye drops.[2][3] As eye drops it is used to treat increased pressure inside the eye such as in ocular hypertension and glaucoma.[2] By mouth it is used for high blood pressure, chest pain due to insufficient blood flow to the heart, to prevent further complications after a heart attack, and to prevent migraines.[3]

Common side effects with the drops is irritation of the eye.[2] Common side effects by mouth include tiredness, slow heart beat, itchiness, and shortness of breath.[3] Other side effects include masking the symptoms of low blood sugar in those with diabetes.[2] Use is not recommended in those with asthma, uncompensated heart failure, or COPD.[2] It is unclear if use during pregnancy is safe for the baby.[4] Timolol is in the non-selective Beta blocker family of medication.[2]

Timolol was patented in 1968 and came into medical use in 1978.[5] It is on the World Health Organization's List of Essential Medicines, the most effective and safe medicines needed in a health system.[6] Timolol is available as a generic medication.[2] The wholesale cost in the developing world is about 0.86 to 2.29 USD per 5 ml bottle.[7] In the United States it costs 25 to 50 USD per month.[8]

Medical uses[edit]

By mouth[edit]

In its by mouth form, it is used:

Eye drops[edit]

In its eye drop form it is used to treat open-angle and, occasionally, secondary glaucoma. The mechanism of action of timolol is probably the reduction of the formation of aqueous humor in the ciliary body in the eye. It was the first β blocker approved for topical use in treatment of glaucoma in the USA (1978). When used by itself, it depresses intraocular pressure (IOP) 18–34% below baseline within first few treatments. However, there are short-term escape and long-term drift effects in some patients. That is, tolerance develops. It may reduce the extent of diurnal IOP curve up to 50%. IOP higher during sleep. It is 5–10× more potent β blocker than propranolol. Timolol is light-sensitive; it is usually preserved with 0.01% benzalkonium chloride (BAC), but also comes BAC-free. Can also be used in adjunctive therapy with pilocarpine or carbonic anhydrase inhibitors.[10]

A Cochrane Systematic Review compared the effect of timolol versus brimonidine in slowing the progression of open angle glaucoma in adult participants.[11]

Side effects[edit]

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.

Side effects when given in the eye include: burning sensation, eye redness, superficial punctate keratopathy, corneal numbness.

Formulations[edit]

It is available in tablet and liquid formulations.

For ophthalmic use, timolol is also available combined:

Brand names[edit]

Timolol is marketed under many trade names worldwide.[1]

References[edit]

  1. ^ a b "Timolol - Drugs.com". www.drugs.com. Archived from the original on 7 March 2016. Retrieved 28 December 2016. 
  2. ^ a b c d e f g "Timolol eent". The American Society of Health-System Pharmacists. Archived from the original on 28 December 2016. Retrieved 8 December 2016. 
  3. ^ a b c "Timolol Maleate". The American Society of Health-System Pharmacists. Archived from the original on 28 December 2016. Retrieved 8 December 2016. 
  4. ^ "Timolol ophthalmic Use During Pregnancy | Drugs.com". www.drugs.com. Archived from the original on 28 December 2016. Retrieved 28 December 2016. 
  5. ^ Fischer, Janos; Ganellin, C. Robin (2006). Analogue-based Drug Discovery. John Wiley & Sons. p. 460. ISBN 9783527607495. Archived from the original on 2016-12-28. 
  6. ^ "WHO Model List of Essential Medicines (19th List)" (PDF). World Health Organization. April 2015. Archived (PDF) from the original on 13 December 2016. Retrieved 8 December 2016. 
  7. ^ "Timolol Maleate". International Drug Price Indicator Guide. Retrieved 8 December 2016. 
  8. ^ Hamilton, Richart (2015). Tarascon Pocket Pharmacopoeia 2015 Deluxe Lab-Coat Edition. Jones & Bartlett Learning. p. 411. ISBN 9781284057560. 
  9. ^ Dawn A. Marcus; Philip A. Bain (27 February 2009). Effective Migraine Treatment in Pregnant and Lactating Women: A Practical Guide. シュプリンガー・ジャパン株式会社. pp. 141–. ISBN 978-1-60327-438-8. Archived from the original on 5 November 2017. Retrieved 14 November 2010. 
  10. ^ Strohmaier, K; Snyder, E; Adamsons, I (Jul 1998). "A multicenter study comparing dorzolamide and pilocarpine as adjunctive therapy to timolol: patient preference and impact on daily life". J Am Optom Assoc. 69 (7): 441–51. PMID 9697378. 
  11. ^ Sena DF, Lindsley K (2017). "Neuroprotection for treatment of glaucoma in adults". Cochrane Database Syst Rev (1): CD006539. doi:10.1002/14651858.CD006539.pub4. PMID 28122126. 

External links[edit]