Pharmacotherapeutic group: Ophthalmologic Diagnostic Agents. ATC code: S01JA01.
Pharmacology: Pharmacodynamics: Fluorescein sodium is a fluorochrome used in medicine as a diagnostic stain. Fluorescein is used to make the blood vessels of the ocular fundus visible (angiography of the retina and choroid). Fluorescein sodium responds to electromagnetic radiation and light between the wavelengths of 465-490 nm and fluoresces, i.e., emits light at wavelengths of 520-530 nm. Thus, the hydrocarbon is excited by blue light and emits light that appears yellowish-green. Following intravenous injection of fluorescein sodium in an aqueous solution, the unbound fraction of the fluorescein can be excited with a blue light flash from a fundus camera as it circulates through the ocular vasculature, and the yellowish green fluorescence of the dye is captured by the camera. In the fundus, the fluorescence of the dye demarcates the retinal and/or choroidal vasculature under observation, distinguishing it from adjacent areas/structures.
Pediatric population: No overall differences in effectiveness have been observed between pediatric and adult patients when dosed based on the patient's body weight.
Pharmacokinetics: Distribution: Within 7 to 14 seconds after intravenous administration into antecubital vein, fluorescein usually appears in the central artery of the eye. Within a few minutes of intravenous administration of fluorescein, a yellowish discoloration of the skin occurs, which begins to fade 6 to 12 hours after dosing. Various estimates of volume of distribution indicate that fluorescein distributes well into interstitial space (0.5 L/kg).
Metabolism: Fluorescein undergoes rapid metabolism to fluorescein monoglucuronide. After intravenous administration of fluorescein sodium (14 mg/kg) to 7 healthy subjects, approximately 80% of fluorescein in plasma was converted to glucuronide conjugate after a period of 1 hour post dose, indicating relatively rapid conjugation.
Excretion: Fluorescein and its metabolites are mainly eliminated via renal excretion. After intravenous administration, the urine remains slightly fluorescent for 24 to 36 hours. A renal clearance of 1.75 mL/min/kg and a hepatic clearance (due to conjugation) of 1.50 mL/min/kg have been estimated. The systemic clearance of fluorescein is essentially complete by 48 to 72 hours after administration of 500 mg fluorescein. Although a longer excretion rate in patients with renal impairment is possible, limited experience in subjects with renal impairment (glomerular filtration rate below 20 mL/min) suggests that, in general, no dose adjustment is required.
Toxicology: Preclinical Safety Data: Non-clinical data for sodium fluorescein reveal no special hazard for humans based on studies of single dose toxicity, genotoxicity and reproductive function.