Naphazoline (in the hydrochloride form) is the common name for 2-(1-naphthylmethyl)-2-imidazoline hydrochloride. It is a sympathomimetic agent with marked alpha adrenergic activity. It is a vasoconstrictor with a rapid action in reducing swelling when applied to mucous membrane . It acts on alpha-receptors in the arterioles of the conjunctiva to produce constriction, resulting in decreased congestion. It is an active ingredient in several over-the-counter formulations including Eucool , Clear Eyes and Naphcon eye drops . 
Xylazine is metabolized by liver cytochrome P450 enzymes.  When it reaches the liver, xylazine is metabolized and proceeds to the kidneys to be excreted as urine.  Around 70% of a dose is excreted by urine.  Thus, urine can be used in detecting xylazine administration because it contains many metabolites , which are the main targets and products in urine.   Within a few hours, xylazine decreases to undetectable levels.  Other factors can also significantly impact the pharmacokinetics of xylazine, including sex, nutrition, environmental conditions, and prior diseases.