![]() | |
![]() | |
Clinical data | |
---|---|
Trade names | Betimol, Blocadren, Istalol, Timoptic, others[1] |
AHFS/Drugs.com | Maleate Monograph eent Monograph |
MedlinePlus | a684029 |
License data | |
Pregnancy category |
|
Routes of administration | By mouth, topical (eye drop) |
Drug class | Beta blocker |
ATC code | |
Legal status | |
Legal status | |
Pharmacokinetic data | |
Bioavailability | 60% |
Metabolism | Liver (80%, mainly CYP2D6[3]) |
Onset of action | 15–30 min[2] |
Elimination half-life | 2.5–5 hours |
Duration of action | 24 hours[2] |
Excretion | Kidney |
Identifiers | |
| |
CAS Number | |
PubChem CID | |
IUPHAR/BPS | |
DrugBank | |
ChemSpider | |
UNII | |
KEGG | |
ChEBI | |
ChEMBL | |
CompTox Dashboard (EPA) | |
ECHA InfoCard | 100.043.651 |
Chemical and physical data | |
Formula | C13H24N4O3S |
Molar mass | 316.42 g·mol−1 |
3D model (JSmol) | |
| |
| |
(verify) |
Timolol is a beta blocker medication used either by mouth or as eye drops.[2][4] 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.[4]
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.[4] 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.[5] Timolol is a non-selective beta blocker.[2]
Timolol was patented in 1968, and came into medical use in 1978.[6] It is on the World Health Organization's List of Essential Medicines.[7] Timolol is available as a generic medication.[2][8] In 2020, it was the 143rd most commonly prescribed medication in the United States, with more than 4 million prescriptions.[9][10]
In its by mouth or oral form, it is used:
The combination of timolol and the alpha-1 blocker prazosin has sedative effects.[12]
In its eye drop form it is used to treat open-angle and, occasionally, secondary glaucoma.[2][13] The mechanism of action of timolol is probably the reduction of the formation of aqueous humor[2] in the ciliary body in the eye. It was the first beta blocker approved for topical use in treatment of glaucoma in the United States (1978).[14] 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 people. That is, tolerance develops. It may reduce the extent of the diurnal IOP curve up to 50%. The IOP is higher during sleep. Efficacy of timolol in lowering IOP during the sleep period may be limited.[15][16][17] It is a 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. It can also be used in combination with pilocarpine, carbonic anhydrase inhibitors[18] or prostaglandin analogs.[19]
A Cochrane review compared the effect of timolol versus brimonidine in slowing the progression of open angle glaucoma in adults but found insufficient evidence to come to conclusions.[20]
In its gel form it is used on the skin to treat infantile hemangiomas.[21]
The medication should not be taken by individuals with:[22]
The most serious possible side effects include cardiac arrhythmias and severe bronchospasms.[22] Timolol can also lead to fainting, congestive heart failure, depression, confusion, worsening of Raynaud's syndrome and impotence.[22]
Side effects when given in the eye include: burning sensation, eye redness, superficial punctate keratopathy, corneal numbness.[24][13]
It is available in tablet and liquid formulations.[22][24]
For ophthalmic use, timolol is also available combined:
Timolol is marketed under many trade names worldwide.[1] Timolol eye drops are marketed under the brand name Istalol among others.[25][26]