Why must latanoprost be dosed every 12 hours?

Why must latanoprost be dosed every 12 hours?

• A. To maintain constant pupil dilation
• B. To prevent rebound mydriasis
• C. To prevent systemic effects
• D. To avoid tachyphylaxis

Answer: (B)

Regular dosing is used to keep the drug’s effect on the eye steady. Latanoprost lowers intraocular pressure by increasing aqueous humor outflow, but its effect fades as the drug clears from the eye. When dosing is inconsistent or stopped, the prostaglandin effect can wane and the pupil can dilate more than desired—rebound mydriasis—which can compromise pressure control or pupil dynamics in eyes at risk. Dosing about every 12 hours maintains a continuous level of the medication in the ocular tissues, reducing the chance of that rebound dilation when the drug levels fall before the next dose. It’s not about keeping the pupil permanently dilated, nor is it primarily about minimizing systemic effects or avoiding tachyphylaxis.

Regular dosing is used to keep the drug’s effect on the eye steady. Latanoprost lowers intraocular pressure by increasing aqueous humor outflow, but its effect fades as the drug clears from the eye. When dosing is inconsistent or stopped, the prostaglandin effect can wane and the pupil can dilate more than desired—rebound mydriasis—which can compromise pressure control or pupil dynamics in eyes at risk. Dosing about every 12 hours maintains a continuous level of the medication in the ocular tissues, reducing the chance of that rebound dilation when the drug levels fall before the next dose. It’s not about keeping the pupil permanently dilated, nor is it primarily about minimizing systemic effects or avoiding tachyphylaxis.