Keros contains Alcaftadine, a histamine H1 receptor antagonist that is used ophthalmic to relieve itching in the treatment of allergic conjunctivitis.

Mechanism of action

Alcaftadine works by blocking histamine H1 receptors, thus inhibiting mast cell release, also reduces chemotaxis and inhibits eosinophil activation.

Pharmacokinetic properties

After bilateral topical ocular administration of 0.25% Keros ophthalmic solution, the maximum plasma concentration Cmax is approximately 60pg / ml and occurs at Tmax of 15 minutes. Three hours after administration, plasma concentrations are below the lower limit of quantification (10 pg / ml). The Cmax of the active carboxylic acid metabolite is approximately 3 ng / ml and is obtained 1 hour after dosing. At 12 hours after administration, the plasma concentrations of the carboxylic acid metabolite are below the limit of quantification (100 pg / ml). No systemic accumulation of Alcaftadine or the active metabolite is observed after daily ocular administration.

Alcaftadine binds to plasma proteins by 39.2% and its metabolite by 62.7%. The metabolism of Alcaftadine is mediated by cytosolic enzymes not belonging to the hepatic isoenzymes that produce the active carboxylic acid metabolite. The elimination half-life of the active metabolite is approximately 2 hours after topical ocular administration. This metabolite is mainly excreted unchanged in the urine.


Each ml contains:

Alcaftadine 2.5 mg

C.S. excipients 1 ml

Posology and administration


Administration route: Ophthalmic.

The recommended dose is: one (1) drop in each affected eye, once a day.


Stay between 15 °C and 25 °C. Protect from freezing.



Box containing a 3 ml dropper bottle.

Medical sample with 1 ml dropper bottle.

Therapeutic indications

Keros is indicated for the treatment and prevention of itching associated with allergic conjunctivitis.


Keros is contraindicated in patients with hypersensitivity to the active substance or to any of the excipients.

Warnings and precautions

Keros may produce temporary blurred vision after application. If it occurs, the patient must refrain from driving or using machinery and performing activities that require good vision, until they are sure that they can be carried out safely.

Keros should be used with caution in women who are breastfeeding, as there is no data if Alcaftadine is excreted in human milk. Similarly, Keros should not be used to treat eye redness or irritation caused by the use of contact lenses.


Keros should only be used in pregnant women if strictly necessary.

Pediatric use

The safety and efficacy of Alcaftadine in children younger than 2 years have not been established.

Drug interactions

There are no known interactions between Alcaftadine and other substances for topical use in the eye.

Side Effects


Eyepieces (<4%): eye irritation, burning and / or stitching sensation in the eyes after instillation, eye redness and itching, eyelid edema.

Non-ocular (<3%): headache, rhinopharyngitis, hypersensitivity, drowsiness.