Noninvasive monitoring of intraocular pharmacokinetics of daunorubicin using fluorophotometry.
OBJECTIVE
Daunorubicin is a cytotoxic drug, which, in nontoxic doses, is effective in preventing cellular proliferation in experimental vitreoretinopathy. We studied dose and clearance of daunorubicin in various ocular tissues using fluorophotometry techniques.


METHODS
In vitro tests: The emission of fluorescence from the daunorubicin solution having a concentration range of 0.1 to 10 micrograms/mL in phosphate buffer was measured using an excitation wavelength range of 489 +/- 10 nm. The emission of fluorescence was measured at 514 nm; the linearity of the response was determined using linear regression analysis. There is a fluorescence peak of daunorubicin at 485 nm. The validity and reproducibility of the method were examined. In vivo tests: The rabbits were randomized into three groups and daunorubicin concentrations of 4, 6, or 8 micrograms/mL were injected into the vitreous. Fluorophotometry scanning from the retina to the anterior chamber was performed with a commercially available fluorophotometer at various times up to 48 hours after injection to quantify fluorescence emission of daunorubicin.


RESULTS
The standard curve of fluorescence versus concentration of daunorubicin was linear in the range of 0.1 to 8 micrograms/mL. It was sensitive up to 0.1 microgram. The daunorubicin time concentration profile showed a dose response relationship over the 48-hour period studied. The half-life of daunorubicin in the vitreous was about 5 hours.


CONCLUSIONS
We performed fluorophotometry using a fluorophotometer whose exciter emits light at 489 nm, which is very close to an absorption peak of daunorubicin. These two values are close enough to obviate the need for modifying the commercial fluorophotometer. Therefore the concentration of daunorubicin in the vitreous cavity can be measured noninvasively.
Kizhakkethara
I
I
LSU Eye Center, Louisiana State University Medical Center School of Medicine, New Orleans 70112-2234, USA.
Li
X
X
el-Sayed
S
S
Khoobehi
B
B
Moshfeghi
D M
DM
Rahimy
M
M
Peyman
G A
GA
D000042:Absorption; D000818:Animals; D000903:Antibiotics, Antineoplastic / Q000008:administration & dosage / Q000493:pharmacokinetics*; D003630:Daunorubicin / Q000008:administration & dosage / Q000493:pharmacokinetics*; D004305:Dose-Response Relationship, Drug; D016903:Drug Monitoring / Q000379:methods*; D005123:Eye / Q000187:drug effects / Q000378:metabolism*; D015590:Fluorophotometry / Q000379:methods*; D007267:Injections; D011817:Rabbits; D011897:Random Allocation; D012044:Regression Analysis; D015203:Reproducibility of Results; D018630:Vitreoretinopathy, Proliferative / Q000378:metabolism / Q000473:pathology / Q000517:prevention & control; D014822:Vitreous Body
D000903:Antibiotics, Antineoplastic; D003630:Daunorubicin