Timolol

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[[]]
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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:

• Combigan - timolol and brimonidine
• Cosopt - timolol maleate and dorzolamide hydrochloride
• DuoTrav - timolol and travoprost
• Xalacom (Pfizer) - timolol and latanoprost

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

de:Timolol