Ocular hypotensive activity of BOL-303259-X, a nitric oxide donating prostaglandin F2α agonist, in preclinical models.

The aim of the study was to investigate the ocular hypotensive activity of a nitric oxide (NO)-donating latanoprost, BOL-303259-X, following topical administration. The effect of BOL-303259-X (also known as NCX 116 and PF-3187207) on intraocular pressure (IOP) was investigated in monkeys with laser-induced ocular hypertension, dogs with naturally-occurring glaucoma and rabbits with saline-induced ocular hypertension. Latanoprost was used as reference drug. NO, downstream effector cGMP, and latanoprost acid were determined in ocular tissues following BOL-303259-X administration as an index of prostaglandin and NO-mediated activities. In primates, a maximum decrease in IOP of 31% and 35% relative to baseline was achieved with BOL-303259-X at doses of 0.036% (9 µg) and 0.12% (36 µg), respectively. In comparison, latanoprost elicited a greater response than vehicle only at 0.1% (30 µg) with a peak effect of 26%. In glaucomatous dogs, IOP decreased from baseline by 44% and 10% following BOL-303259-X (0.036%) and vehicle, respectively. Latanoprost (0.030%) lowered IOP by 27% and vehicle by 9%. Intravitreal injection of hypertonic saline in rabbits increased IOP transiently. Latanoprost did not modulate this response, whereas BOL-303259-X (0.036%) significantly blunted the hypertensive phase. Following BOL-303259-X treatment, latanoprost acid was significantly elevated in rabbit and primate cornea, iris/ciliary body and aqueous humor as was cGMP in aqueous humor. BOL-303259-X lowered IOP more effectively than latanoprost presumably as a consequence of a contribution by NO in addition to its prostaglandin activity. The compound is now in clinical development for the treatment of glaucoma and ocular hypertension.

[Circadian rhythm variations of intraocular pressure and therapeutic decisions: interpretation of clinical trial results based on a statistical model]. / Variations nycthémérales de la pression intraoculaire et décisions thérapeutiques: Interprétation des résultats d'essais cliniques à partir d'un modèle statistique.

Therapeutic decisions (treatment initiation, continuation, change, combination, etc.) based on intraocular pressure (IOP) monitoring require knowledge of both circadian IOP fluctuations and the pharmacological circadian rhythm of the active ingredients. A simple model was applied to data from two clinical trials to estimate the consequences of circadian IOP fluctuations on (1) ocular hypertension diagnosis, (2) therapeutic adjustments, and (3) the daily cumulative effect of marginally low therapeutic differences. A grid for clinical interpretation of the average IOP differences is presented. The probability of an IOP that exceeds the target value for the diagnosis or therapy varied to a large extent throughout the day. IOP was higher in the morning than in the evening. The IOP variance (measured by standard deviation) was an important factor in decision-making, regardless of the IOP value itself. Regular IOP monitoring over the entire day allowed minimization of the time spent above a target value. IOP differences that seemed low when expressed in average values in therapeutic trials could have clinically significant consequences in the practitioner's decisions. The data presented suggest that ocular hypertension diagnosis and therapeutic decisions should be made early in the morning, at least for most patients. In any case, the time of the measurement should be considered in the therapeutic approach.

The ocular effects of prostaglandins and the therapeutic potential of a new PGF2 alpha analog, PhXA41 (latanoprost), for glaucoma management.

In the early days of prostaglandin (PG) research, the infusion of large PG doses into rabbit eyes already traumatized by cannulation, led to the conclusion that PGs have a profound ocular hypertensive effect that is associated with a breakdown of the blood-aqueous barrier. In contrast, repeated topical application of PGs to nontraumatized eyes of several species other than rabbits has later been shown to yield a maintained ocular hypotensive effect, without barrier breakdown. Due to its excellent pharmacokinetic properties, the isopropyl ester form of PGF2 alpha (PGF2 alpha-IE) is a much more potent ocular hypotensive agent and appeared to be better suited for the management of glaucoma, than PGF2 alpha itself or any currently used glaucoma drug. However, even this prodrug caused clinically unacceptable foreign-body sensation and conjunctival hyperemia, which could be reduced, or eliminated, only by some modifications of the omega chain of PGF2 alpha-IE. One such analog, PhXA41, maintained highly significant IOP reduction in glaucoma patients even with once-daily application at the remarkably low concentration of 0.006%. Because PhXA41 reaches intraocular tissues and the systemic circulation in its de-esterified free-acid form, which is a good substrate for the PG transport system, it retains the most important pharmacokinetic advantages of topically applied PGF2 alpha-IE. However, its greatly reduced side effects give PhXA41 a clear therapeutic advantage over PGF2 alpha-IE, making it an effective new drug candidate for the long-term medical management of glaucoma.