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Drug Interactions between didanosine and gatifloxacin

This report displays the potential drug interactions for the following 2 drugs:

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Interactions between your drugs

Moderate

didanosine gatifloxacin

Applies to: didanosine and gatifloxacin

ADJUST DOSING INTERVAL: Concomitant administration with didanosine buffered tablets or pediatric oral solution may reduce the oral bioavailability of gatifloxacin and other quinolone antibiotics. The mechanism is reduced quinolone absorption due to chelation with metallic cations from buffering agents and antacids used in certain formulations of didanosine. In 24 healthy volunteers, administration of an antacid containing aluminum oxide-magnesium hydroxide (1800 mg-1200 mg/20 mL dose) 2 hours before, simultaneously, and 2 hours after a single 400 mg dose of gatifloxacin reduced the relative bioavailability of gatifloxacin by 42%, 64%, and 18%, respectively. Administration of the antacid 4 hours after gatifloxacin showed no effect. The pharmacokinetics of gatifloxacin have not been studied in combination with the various didanosine formulations, but significant reductions in bioavailability have been reported for ciprofloxacin, another quinolone, in interaction studies with didanosine.

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 (9)
  1. Polk RE (1989) "Drug-drug interactions with ciprofloxacin and other fluoroquinolones." Am J Med, 87, s76-81
  2. Marchbanks CR (1993) "Drug-drug interactions with fluoroquinolones." Pharmacotherapy, 13, s23-8
  3. (2002) "Product Information. Videx (didanosine)." Bristol-Myers Squibb
  4. Sahai J, Gallicano K, Oliveras L, Khaliq S, Hawley-Foss N, Garber G (1993) "Cations in the didanosine tablet reduce ciprofloxacin bioavailability." Clin Pharmacol Ther, 53, p. 292-7
  5. Deppermann KM, Lode H (1993) "Fluoroquinolones: interaction profile during enteral absorption." Drugs, 45 Suppl 3, p. 65-72
  6. Knupp CA, Barbhaiya RH (1997) "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, p. 65-77
  7. Lober S, Ziege S, Rau M, Schreiber G, Mignot A, Koeppe P, Lode H (1999) "Pharmacokinetics of gatifloxacin and interaction with an antacid containing aluminum and magnesium." Antimicrob Agents Chemother, 43, p. 1067-71
  8. (2001) "Product Information. Tequin (gatifloxacin)." Bristol-Myers Squibb
  9. Damle BD, Mummaneni V, Kaul S, Knupp C (2002) "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, p. 385-91

Drug and food interactions

Moderate

didanosine food

Applies to: didanosine

ADJUST DOSING INTERVAL: Didanosine bioavailability is decreased when administered with food. Loss of efficacy may result.

MANAGEMENT: Didanosine should be administered in the fasting state, at least 30 minutes before or more than 2 hours after eating.

References (1)
  1. (2002) "Product Information. Videx (didanosine)." Bristol-Myers Squibb
Minor

gatifloxacin food

Applies to: gatifloxacin

Concurrent ingestion of calcium-fortified foods (i.e., cereal, orange juice) may alter the bioavailability of gatifloxacin. The mechanism is chelation of calcium and the quinolone, resulting in decreased bioavailability. In the case of orange juice, inhibition of intestinal transport mechanisms (P-glycoprotein or organic anion-transporting polypeptides) by flavones may also be involved. Data have been conflicting: One study has reported no effect with milk coadministration. Another study reported a modest decrease in gatifloxacin bioavailability (13.5% decrease in Cmax,12% decrease in AUC, 15% increase in total clearance) when taken with 12 ounces of calcium-fortified orange juice instead of water, which could be clinically significant if the infecting organisms have borderline susceptibilities. The manufacturer states that gatifloxacin may be taken without regard to food, milk, or calcium. Clinicians should be aware of the possibility of an interaction if subtherapeutic effects are observed.

References (2)
  1. (2001) "Product Information. Tequin (gatifloxacin)." Bristol-Myers Squibb
  2. Wallace AW, Victory JM, Amsden GW (2003) "Lack of bioequivalence of gatifloxacin when coadministered with calcium-fortified orange juice in healthy volunteers." J Clin Pharmacol, 43, p. 92-6

Therapeutic duplication warnings

No warnings were found for your selected drugs.

Therapeutic duplication warnings are only returned when drugs within the same group exceed the recommended therapeutic duplication maximum.

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Drug Interaction Classification

These classifications are only a guideline. The relevance of a particular drug interaction to a specific individual is difficult to determine. Always consult your healthcare provider before starting or stopping any medication.
Major Highly clinically significant. Avoid combinations; the risk of the interaction outweighs the benefit.
Moderate Moderately clinically significant. Usually avoid combinations; use it only under special circumstances.
Minor Minimally clinically significant. Minimize risk; assess risk and consider an alternative drug, take steps to circumvent the interaction risk and/or institute a monitoring plan.
Unknown No interaction information available.

Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

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