Section 7-C-1: Prostaglandin Analogs

Prostaglandins are chemicals made within the tissues of the body. Receptors exist for each of the various prostaglandins and have different physiologic effects on the body. When activated by prostaglandin PGF2alpha (prostaglandin PGF2 alpha, dinoprost), the nonconventional outflow (uveoscleral outflow) is improved with resulting decrease in IOP.

Latanoprost (Xalatan, Figure 7-2 A) was the first prostaglandin developed for the treatment of glaucoma and has been shown to effectively lower IOP with once daily dosing at bedtime. It is suggested that unopen bottles of latanoprost be refrigerated, and once open, can be stored at room temperature. A latanoprost/timolol combination (Xalcom) has been approved in Europe, but not in the US. Similar agents, such as travoprost (Travatan, Figure 7-2 B) and bimatoprost (Lumigan, Figure 7-2 C), have been shown to lower IOP with once daily dosing as well. Unoprostone (Rescula) is another prostaglandin analog; it has the disadvantage of being dosed twice daily.

Figure 7-2. Prostaglandin Analogs
A. Latanoprost 0.005% (Xalatan, Pfizer Inc., New York, NY)	B. Travoprost 0.004% (Travatan, Alcon Inc., Fort Worth, TX)	C. Bimatoprost 0.03% (Lumigan, Allergan Inc., Irvine, CA)

Prostaglandins are quickly becoming important first line agents in the treatment of glaucoma. They are well-tolerated and lack significant systemic side effects. They have the added benefit of once daily dosing.
Ocular side effects include redness, irritation, corneal toxicity in those with a history of herpes simplex keratitis, inflammation, increased pigmentation of periocular skin, iris darkening (especially in hazel/green eye color), and increased length and number of eyelashes. As noted in Table 7-3, the side effects of prostaglandins are primarily ocular. No significant systemic side effects from prostaglandins give it an added advantage over other glaucoma medications. Another added benefit is its once daily dosing. In addition, the ocular side effects are often well-tolerated. The redness and irritation that occur initially tend to improve with time.

Table 7-3: Ocular side effects of prostaglandins:

Redness

Irritation

Exacerbation of herpes simplex keratitis

Inflammation

Change of periocular skin/iris color

Increased length and number of lashes

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