[Suppressing effect of isoforskolin and forskolin on ocular hypertension in rabbits].
OBJECTIVE
To examine the effects of isoforskolin (isoF) and forskolin (FSK) suspensions administered topically on eyes with ocular hypertension (OHT) and observe the local irritation of the drugs.


METHODS
The intraocular pressure (IOP) was measured with pneumotonometer in screened spontaneous or water-loading induced OHT rabbits for evaluation of drug effects, and the irritation indices were recorded as well.


RESULTS
In screened OHT rabbits, isoF significantly lowered IOP from 0.5 to at least 4.5 h after the administration (P < 0.05, paired t-test vs. contralateral control eyes), with the maximum decreases of 0.25% and 1% isoF reaching 8.1 mm Hg and 7.0 mm Hg (1 mm Hg = 0.133 kPa) at about 1.5 h later, respectively. In water-loaded OHT rabbits, both 0.06%, 0.1%, 0.25%, 1% isoF and 1% FSK concentration-dependently suppressed the increments of IOP (P < 0.05 with the exception of 0.06% isoF) induced by water-loading, and the peak effects of the optimal concentration of 0.25% isoF and 1% FSK were 7.1 and 6.9 mm Hg (difference of IOP between bilateral eyes) respectively. The results also indicated that 0.25% isoF or FSK suspension had basically no irritation, but 1% induced slight irritating responses during the experiment.


CONCLUSIONS
Both isoF and FSK had suppressing effects on OHT in rabbits with the optimal concentration being 0.25% and 1% respectively; at concentration of 0.25%, topically both drugs had basically no irritation, while 1% of the drugs may induce mild irritating responses.
Li
X
X
Yunnan Pharmacological Laboratories of Natural Products, Kunming Medical College, Kunming 650031, China.
Nie
L
L
Yang
W
W
Chen
Z
Z
Wang
X
X
Luo
L
L
D000818:Animals; D000959:Antihypertensive Agents / Q000008:administration & dosage; D005576:Colforsin / Q000008:administration & dosage / Q000031:analogs & derivatives / Q000627:therapeutic use*; D007429:Intraocular Pressure / Q000187:drug effects; D009798:Ocular Hypertension / Q000188:drug therapy*; D009883:Ophthalmic Solutions / Q000627:therapeutic use; D011817:Rabbits
D000959:Antihypertensive Agents; D009883:Ophthalmic Solutions; D005576:Colforsin