Drug General Information (ID: DDIR7FQ4XZ)
Drug Name			Didanosine		Drug Info		Gatifloxacin		Drug Info
Drug Type		Small molecule				Small molecule
Therapeutic Class		Anti-Hiv Agents				Antiinfective Agents
Structure

Mechanism of Didanosine-Gatifloxacin Interaction (Severity Level: Moderate)
Complex formation Click to Show/Hide Mechanism Graph
Drug Name		Didanosine				Gatifloxacin
Mechanism		Polyvalent cations				Binds to polyvalent cations
Key Mechanism Factor 1
		Factor Name		Chelation
		Factor Description		Chelation is a direct drug interaction that usually involves the formation of dimers or trimers, resulting in larger complexes and poorer absorption.
Mechanism Description		Decreased absorption of Didanosine due to formation of complexes caused by Gatifloxacin

Recommended Action
Management		Gatifloxacin should be administered at least 4 hours before didanosine buffered tablets or pediatric oral solution, and patients should be monitored for potentially decreased antimicrobial efficacy during concomitant therapy. Didanosine buffered powder for oral solution, which uses a citrate-phosphate buffer, and the delayed-release capsules, which are not buffered, are not expected to cause this interaction.

References
1	Deppermann KM, Lode H "Fluoroquinolones: interaction profile during enteral absorption." Drugs 45 Suppl 3 (1993): 65-72. [PMID: 7689454]
2	Knupp CA, Barbhaiya RH "A multiple-dose pharmacokinetic interaction study between didanosine (videx(r)) and ciprofloxacin (cipro(r)) in male subjects seropositive for HIV but asymptomatic." Biopharm Drug Dispos 18 (1997): 65-77. [PMID: 9008270]
3	Lober S, Ziege S, Rau M, Schreiber G, Mignot A, Koeppe P, Lode H "Pharmacokinetics of gatifloxacin and interaction with an antacid containing aluminum and magnesium." Antimicrob Agents Chemother 43 (1999): 1067-71. [PMID: 10223915]
4	Marchbanks CR "Drug-drug interactions with fluoroquinolones." Pharmacotherapy 13 (1993): s23-8. [PMID: 8474934]
5	Polk RE "Drug-drug interactions with ciprofloxacin and other fluoroquinolones." Am J Med 87 (1989): s76-81. [PMID: 2686430]
6	Product Information. Tequin (gatifloxacin) Bristol-Myers Squibb, Princeton, NJ.
7	Product Information. Videx (didanosine). Bristol-Myers Squibb, Princeton, NJ.
8	Sahai J, Gallicano K, Oliveras L, Khaliq S, Hawley-Foss N, Garber G "Cations in the didanosine tablet reduce ciprofloxacin bioavailability." Clin Pharmacol Ther 53 (1993): 292-7. [PMID: 8453847]
9	Damle BD, Mummaneni V, Kaul S, Knupp C "Lack of Effect of Simultaneously Administered Didanosine Encapsulated Enteric Bead Formulation (Videx EC) on Oral Absorption of Indinavir, Ketoconazole, or Ciprofloxacin." Antimicrob Agents Chemother 46 (2002): 385-91. [PMID: 11796346]