Combigan is used in the form of eye drops to lower the elevated intraocular pressure in glaucoma, specifically in cases of open-angle glaucoma. It is especially used when treatment with beta-blockers alone is not tolerated or the desired results are not achieved.
Its active ingredients are Timolol and Brimonidine. Timolol belongs to the group of non-selective beta-blockers, since it is not a specific beta-receptor binder. It also has no intrinsic sympathomimetic activity (ISA). Timolol inhibits beta-receptors in the ciliary body of the eye and therefore reduces the production of aqueous humor. The reduced aqueous humor formation leads to reduction of intraocular pressure. The relative potency of Timolol is much higher compared to propranolol. The fat-soluble Timolol is well absorbed after oral administration. Its bioavailability is about 50 to 60%. The plasma half-life of Timolol is about 4 to 5 hours. It is metabolized up to 80% in the liver. The plasma protein binding of Timolol is 60%, 30% of it is excreted by feces and 70% by urine.
Brimonidine belongs to the alpha-sympatholytic group of drugs. It is used specifically to bind alpha-receptors in the eye. Alpha-receptors are specific binding sites of sympathetic fibers of the autonomic nervous system. They are normally activated by the body's own neurotransmitters (such as epinephrine and norepinephrine). Brimonidine replaces these endogenous neurotransmitters from the receptors, thereby suppressing their effect. The biological half-life of brimonidine is approximately four hours.
During pregnancy, Combigan may be taken only if the doctor considers it absolutely necessary. Lactating women should not use Combigan at all. Combigan is not recommended for newborns and children. Only under careful medical risk-benefit assessment, Combigan should be used in patients with severe or untreated cardiovascular disease, depression, vascular disease (reduced blood flow in brain arteries or coronary arteries, Raynaud's syndrome, Winiwarter-Buerger's disease) and low blood pressure upon standing (orthostatic syndrome). The same applies to the use of Combigan for patients with impaired liver or kidney function.
Combigan should not be used on the eye while wearing soft contact lenses. Hard contact lenses should be removed before use and Combigan should be applied only after 15-20 minutes. Take the missed dose as soon as you recall it. But if it’s too late to take the missed dose, proceed with the next one.
The common side effects of Combigan usage include: watering eyes, dryness of the eye, redness of the eye, headaches and dizziness, fatigue, fainting, depression, bradycardia, cough, signs of allergic reaction, nausea, vomiting, diarrhea, decreased appetite.
