Drug General Information (ID: DDI42FTMAD)
Drug Name			Doxycycline		Drug Info		Lactic acid		Drug Info
Drug Type		Small molecule				Small molecule
Therapeutic Class		Antiinflammatory Agents				Topical Agents
Structure

Mechanism of Doxycycline-Lactic acid Interaction (Severity Level: Moderate)
Altered urine pH Click to Show/Hide Mechanism Graph
Drug Name		Doxycycline				Lactic acid
Mechanism		Urine pH sensitive				Urine alkalinizer
Key Mechanism Factor 1
		Factor Name		Urine pH
		Factor Description		The normal range of urine pH is between 4.5 and 8, depending mainly on the hydrogen ion concentration. Changes in urine pH may significantly affect drug reabsorption and excretion.
Mechanism Description		Altered elimination of Doxycycline caused by Lactic acid mediated altered urine pH

Recommended Action
Management		If these drugs must be used together, an alternating dosing schedule is recommended (three to four hours apart).

References
1	Elliott GR "Sodium bicarbonate and oral tetracycline." Clin Pharmacol Ther 13 (1972): 459. [PMID: 5026384]
2	Jaffe JM, Colaizzi JI, Poust RI, McDonald RH Jr "Effect of altered urinary pH on tetracycline and doxycycline excretion in humans." J Pharmacokinet Biopharm 1 (1973): 267-82.
3	Jaffe JM, Poust RI, Feld SL, Colaizzi JL "Influence of repetitive dosing and altered urinary pH on doxycycline excretion in humans." J Pharm Sci 63 (1974): 1256-60. [PMID: 4852448]