The half life for Doxy is approximately 18-22 hours.
Half-life: time taken for blood concentration to fall to half its peak value after a single dose. . This time may vary considerably between individuals. A drug
is determined by finding out how long it takes a
medication or drug
to be eliminated from blood plasma
by one half
of its strength.
You could ask your pharmacy to calculate the clearance of this drug from your system as it will depend on the dosage.