Cardiovascular effects of topical ophthalmic 10% phenylephrine in dogs.
OBJECTIVE
To evaluate the effect of topical ophthalmic 10% phenylephrine on systolic arterial pressure (SAP), diastolic arterial pressure (DAP), mean arterial pressure (MAP), pulse rate (PR) and electrocardiogram (ECG) in dogs.


METHODS
Nine clinically normal dogs.


METHODS
Arterial catheters were placed in the dorsal pedal artery of awake dogs and ECG leads were attached. After a 15-min acclimatization period, baseline PR, SAP, DAP and MAP were recorded every 5 min for 20 min. Two treatment groups (eight dogs each) were studied. Group I: one drop of phenylephrine was placed in each eye once. Group II: one drop of phenylephrine was placed in each eye three times at 5-min intervals. Following treatment, PR, SAP, DAP and MAP were recorded every 5 min for 90 min. The mixed procedure of the SAS system was used to perform a repeated measures analysis of variance to test for linear and quadratic trends across time.


RESULTS
Group I: There was a significant quadratic decrease in PR across time (P = 0.0051). Systolic arterial pressure increased linearly with time (P = 0.0002), MAP increased linearly with time (P = 0.0131), and DAP increased linearly with time (P = 0.0001). Group II: There was a significant quadratic decrease in PR across time (P = 0.0023). There was a significant quadratic increase in SAP (P = 0.0324), MAP (P = 0.0103) and DAP (P = 0.0131) across time.


CONCLUSIONS
Topical ophthalmic application of 10% phenylephrine in normal dogs results in elevation of arterial blood pressure and reflex bradycardia.
Herring
I P
IP
Department of Small Animal Clinical Sciences, VA-MD Regional College of Veterinary Medicine, Blacksburg, VA 24061-0442, USA. iherring@vt.edu
Jacobson
J D
JD
Pickett
J P
JP
D000287:Administration, Topical; D000818:Animals; D001794:Blood Pressure / Q000187:drug effects; D002319:Cardiovascular System / Q000187:drug effects*; D004285:Dogs; D004562:Electrocardiography / Q000187:drug effects; D005260:Female; D006339:Heart Rate / Q000187:drug effects; D008297:Male; D009184:Mydriatics / Q000008:administration & dosage / Q000494:pharmacology*; D009883:Ophthalmic Solutions / Q000008:administration & dosage / Q000494:pharmacology*; D010656:Phenylephrine / Q000008:administration & dosage / Q000494:pharmacology*; D012016:Reference Values
D009184:Mydriatics; D009883:Ophthalmic Solutions; D010656:Phenylephrine