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Drug Interactions between ampicillin / probenecid and ganciclovir

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

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Interactions between your drugs

Moderate

probenecid ganciclovir

Applies to: ampicillin / probenecid and ganciclovir

MONITOR: The coadministration of probenecid and ganciclovir may result in elevated plasma concentrations of ganciclovir. In 10 subjects with HIV infection, probenecid (500 mg orally every 6 hours) increased the peak plasma concentration and area under the concentration-time curve of ganciclovir (1 gram orally every 8 hours) by an average of 40% and 53%, respectively. Renal clearance decreased an average of 22%. The mechanism of the interaction is competitive inhibition of ganciclovir renal tubular secretion by probenecid.

MANAGEMENT: Caution is advised if ganciclovir or its prodrug, valganciclovir, must be used concomitantly with probenecid. Close monitoring for toxicities associated with ganciclovir such as myelosuppression is recommended during concurrent therapy.

References (3)
  1. (2002) "Product Information. Cytovene (ganciclovir)." Genentech
  2. (2001) "Product Information. Valcyte (valganciclovir)." Roche Laboratories
  3. Cimoch PJ, Lavelle J, Pollard R, et al. (1998) "Pharmacokinetics of oral ganciclovir alone and in combination with zidovudine, didanosine, and probenecid in HIV-infected subjects." J Acquire Immune Defic Hum Retrovirol, 17, p. 227-34
Minor

ampicillin probenecid

Applies to: ampicillin / probenecid and ampicillin / probenecid

Probenecid may increase the plasma concentrations and half-lives of penicillins. The mechanism is competitive inhibition by probenecid of the renal tubular secretion of penicillins. While this interaction is often exploited to enhance the antibacterial effect of penicillins, toxicity may occur and should be considered if high penicillin dosages are administered intravenously.

References (6)
  1. Sommers DK, Schoeman HS (1987) "Drug interactions with urate excretion in man?" Eur J Clin Pharmacol, 32, p. 499-502
  2. Waller ES, Sharanevych MA, Yakatan GJ (1982) "The effect of probenecid on nafcillin disposition." J Clin Pharmacol, 22, p. 482-9
  3. Shanson DC, McNabb R, Hajipieris P (1984) "The effect of probenecid on serum amoxycillin concentrations up to 18 hours after a single 3g oral dose of amoxycillin: possible implications for preventing endocarditis." J Antimicrob Chemother, 13, p. 629-32
  4. Sutherland R, Croydon EA, Rolinson GN (1972) "Amoxycillin: a new semi-synthetic penicillin." Br Med J, 3, p. 13-6
  5. Allen MB, Fitzpatrick RW, Barratt A, Cole RB (1990) "The use of probenecid to increase the serum amoxycillin levels in patients with bronchiectasis." Respir Med, 84, p. 143-6
  6. Gibaldi M, Schwartz MA (1968) "Apparent effect of probenecid on the distribution of penicillins in man." Clin Pharmacol Ther, 9, p. 345-9

Drug and food interactions

Moderate

ampicillin food

Applies to: ampicillin / probenecid

ADJUST DOSING INTERVAL: Certain penicillins may exhibit reduced gastrointestinal absorption in the presence of food. The therapeutic effect of the antimicrobial may be reduced.

MANAGEMENT: The interacting penicillin should be administered one hour before or two hours after meals. Penicillin V and amoxicillin are not affected by food and may be given without regard to meals.

References (6)
  1. Neu HC (1974) "Antimicrobial activity and human pharmacology of amoxicillin." J Infect Dis, 129, s123-31
  2. Welling PG, Huang H, Koch PA, Madsen PO (1977) "Bioavailability of ampicillin and amoxicillin in fasted and nonfasted subjects." J Pharm Sci, 66, p. 549-52
  3. McCarthy CG, Finland M (1960) "Absorption and excretion of four penicillins." N Engl J Med, 263, p. 315-26
  4. Cronk GA, Wheatley WB, Fellers GF, Albright H (1960) "The relationship of food intake to the absorption of potassium alpha-phenoxyethyl penicillin and potassium phenoxymethyl penicillin from the gastrointestinal tract." Am J Med Sci, 240, p. 219-25
  5. Klein JO, Sabath LD, Finland M (1963) "Laboratory studies on oxacillin. I: in vitro activity against staphylococci and some other bacterial pathogens. II: absorption and urinary excretion in normal young." Am J Med Sci, 245, p. 399-411
  6. Neuvonen PJ, Elonen E, Pentikainen PJ (1977) "Comparative effect of food on absorption of ampicillin and pivampicillin." J Int Med Res, 5, p. 71-6
Moderate

ganciclovir food

Applies to: ganciclovir

ADJUST DOSING INTERVAL: Food delays but enhances the oral absorption and bioavailability of ganciclovir capsules, possibly due to prolongation of gastrointestinal transit time. In 20 HIV- and CMV-seropositive subjects, ganciclovir dosing (1000 mg every 8 hours) following a standardized high-fat breakfast increased the mean steady-state peak plasma concentration (Cmax) and area under the concentration-time curve (AUC) of ganciclovir by an average of 15% and 22%, respectively, compared to dosing after an overnight fast. The time to reach peak plasma concentration (Tmax) was prolonged from 1.8 to 3 hours. In another study of 15 such patients, administration of ganciclovir (2000 mg) within 30 minutes following a high-fat breakfast increased the Cmax and AUC an average of 111% and 114%, respectively, compared to administration in the fasting state (i.e. at least 1 hour before or 2 hours after a meal or snack). Over the total day of dosing (2000 mg orally three times a day), there was a mean increase of 48% and 97% in Cmax and AUC, respectively, and a 36% decrease in half-life during administration with meals.

MANAGEMENT: To ensure maximal oral absorption, oral ganciclovir should be administered with or immediately after a meal.

References (3)
  1. (2002) "Product Information. Cytovene (ganciclovir)." Genentech
  2. Lavelle J, Follansbee S, Trapnell CB, Buhles WC, Griffy KG, Jung D, Dorr A, Conner J (1996) "Effect of food on the relative bioavailability of oral ganciclovir." J Clin Pharmacol, 36, p. 238-41
  3. Jung D, Griffy K, Dorr A (1999) "Effect of food on high-dose oral ganciclovir disposition in HIV-positive subjects." J Clin Pharmacol, 39, p. 161-5

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

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