A study of aminolevulinic acid-induced protoporphyrin IX fluorescence kinetics in the canine oral cavity.
OBJECTIVE
5-Aminolevulinic acid-induced protoporphyrin IX is a promising photosensitizer that could enhance the spectroscopic contrast between normal and diseased oral tissues. Knowledge of the pharmacokinetics and effects on tissue type are important for diagnostic and therapeutic procedures.


METHODS
Dogs randomly were administered five doses of 5-aminolevulinic acid: 5, 25, 50, 75, and 100 mg/kg. The fluorescence was recorded from buccal mucosa, gums, tongue, and facial skin using a fiberoptic probe connected to an optical multichannel analyzer. Blood samples were collected for hematologic and serum biochemical analysis. Pharmacokinetic parameters of interest were estimated using a compartmental model.


RESULTS
Protoporphyrin fluorescence at all sites reached a peak in 2-6 hours, and returned to baseline in 24-31 hours, depending on the dose. Plasma protoporphyrin peaked earlier than oral tissues.


CONCLUSIONS
The rate of synthesis of protoporphyrin, and its conversion to heme products are dose dependent. Different tissues have different pharmacokinetic response.
Vaidyanathan
V V
VV
Bioengineering Program, Texas A&M University, College Station, Texas 77843, USA.
Rastegar
S
S
Fossum
T W
TW
Flores
P
P
van Der Breggen
E W
EW
Egger
N G
NG
Jacques
S L
SL
Motamedi
M
M
D000622:Aminolevulinic Acid / Q000008:administration & dosage / Q000097:blood / Q000494:pharmacology*; D000818:Animals; D004285:Dogs; D004305:Dose-Response Relationship, Drug; D005145:Face; D005260:Female; D005336:Fiber Optic Technology / Q000295:instrumentation; D005453:Fluorescence; D005881:Gingiva / Q000187:drug effects / Q000378:metabolism / Q000473:pathology; D006418:Heme / Q000378:metabolism; D007091:Image Processing, Computer-Assisted; D009055:Mouth / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology; D009061:Mouth Mucosa / Q000187:drug effects / Q000378:metabolism / Q000473:pathology; D017319:Photosensitizing Agents / Q000008:administration & dosage / Q000097:blood / Q000493:pharmacokinetics / Q000494:pharmacology*; D011524:Protoporphyrins / Q000097:blood / Q000493:pharmacokinetics*; D011897:Random Allocation; D012867:Skin / Q000187:drug effects / Q000378:metabolism / Q000473:pathology; D013050:Spectrometry, Fluorescence; D013997:Time Factors; D014059:Tongue / Q000187:drug effects / Q000378:metabolism / Q000473:pathology
D017319:Photosensitizing Agents; D011524:Protoporphyrins; D006418:Heme; D000622:Aminolevulinic Acid; C028025:protoporphyrin IX