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Drug Interactions between pseudoephedrine / terfenadine and Rexavite 150

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

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Interactions between your drugs

Minor

ascorbic acid pseudoephedrine

Applies to: Rexavite 150 (ascorbic acid / iron polysaccharide) and pseudoephedrine / terfenadine

Acidic urine increases the elimination of ephedrine and pseudoephedrine and decreases the elimination half-life. The clinical significance is unknown. The therapeutic effects of these agents may be decreased.

References

  1. Brater DC, Kaojarern S, Benet LZ, et al. "Renal excretion of pseudoephedrine." Clin Pharmacol Ther 28 (1980): 690-4
  2. Wilkinson GR, Beckett AH "Absorption metabolism and excretion of the ephedrines in man. I. The influence of urinary pH and urine volume output." J Pharmacol Exp Ther 162 (1968): 139-47
  3. Kuntzman RG, Tsai I, Brand L, Mark LC "The influence of urinary pH on the plasma half-life of pseudoephedrine in man and dog and a sensitive assay for its determination in human plasma." Clin Pharmacol Ther 12 (1971): 62-7

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Drug and food interactions

Major

terfenadine food

Applies to: pseudoephedrine / terfenadine

CONTRAINDICATED: The consumption of grapefruit juice has been associated with significantly increased plasma concentrations of terfenadine. The mechanism is inhibition of CYP450 3A4-mediated first-pass metabolism in the gut wall induced by certain compounds present in grapefruits. Terfenadine in high serum levels has been associated with prolongation of the QT interval and development of torsade de pointes, a potentially fatal ventricular arrhythmia.

MANAGEMENT: Due to the risk of cardiotoxicity, patients receiving the drug should be advised to avoid consumption of grapefruit products. Loratadine, cetirizine, and fexofenadine may be safer alternatives in patients who may have trouble adhering to the dietary restriction.

References

  1. Honig PK, Woosley RL, Zamani K, Conner DP, Cantilena LR Jr "Changes in the pharmacokinetics and electrocardiographic pharmacodynamics of terfenadine with concomitant administration of erythromycin." Clin Pharmacol Ther 52 (1992): 231-8
  2. Zimmermann M, Duruz H, Guinand O, et al. "Torsades de Pointes after treatment with terfenadine and ketoconazole." Eur Heart J 13 (1992): 1002-3
  3. Mathews DR, McNutt B, Okerholm R, et al. "Torsades de pointes occurring in association with terfenadine use." JAMA 266 (1991): 2375-6
  4. Monahan BP, Ferguson CL, Killeavy ES, et al. "Torsades de pointes occurring in association with terfenadine use." JAMA 264 (1990): 2788-90
  5. Honig PK, Wortham DC, Zamani K, et al. "Terfenadine-ketoconazole interaction: pharmacokinetic and electrocardiographic consequences." JAMA 269 (1993): 1513-8
  6. Pohjola-Sintonen S, Viitasalo M, Toivonene L, Neuvonen P "Torsades de pointes after terfenadine-itraconazole interaction." BMJ 306 (1993): 186
  7. Cortese LM, Bjornson DC "Potential interaction between terfenadine and macrolide antibiotics." Clin Pharm 11 (1992): 675
  8. Paris DG, Parente TF, Bruschetta HR, Guzman E, Niarchos AP "Torsades-de-pointes induced by erythromycin and terfenadine." Am J Emerg Med 12 (1994): 636-8
  9. Zechnich AD, Haxby DG "Drug interactions associated with terfenadine and related nonsedating antihistamines." West J Med 164 (1996): 68-9
  10. Honig PK, Wortham DC, Lazarev A, Cantilena LR "Grapefruit juice alters the systemic bioavailability and cardiac repolarization of terfenadine in poor metabolizers of terfenadine." J Clin Pharmacol 36 (1996): 345-51
  11. Woosley RL "Cardiac actions of antihistamines." Annu Rev Pharmacol Toxicol 36 (1996): 233-52
  12. Benton RE, Honig PK, Zamani K, Cantilena LR, Woosley RL "Grapefruit juice alters terfenadine pharmacokinetics resulting in prolongation of repolarization on the electrocardiogram." Clin Pharmacol Ther 59 (1996): 383-8
  13. Hsieh MH, Chen SA, Chiang CE, et al. "Drug-induced torsades de pointes in one patient with congenital long QT syndrome." Int J Cardiol 54 (1996): 85-8
  14. Clifford CP, Adams DA, Murray S, Taylor GW, Wilkins MR, Boobis AR, Davies DS "Pharmacokinetic and cardiac effects of terfenadine after inhibition of its metabolism by grapefruit juice." Br J Clin Pharmacol 42 (1996): p662
  15. Rau SE, Bend JR, Arnold JMO, Tran LT, Spence JD, Bailey DG "Grapefruit juice terfenadine single-dose interaction: Magnitude, mechanism, and relevance." Clin Pharmacol Ther 61 (1997): 401-9
  16. Bailey DG, Malcolm J, Arnold O, Spence JD "Grapefruit juice-drug interactions." Br J Clin Pharmacol 46 (1998): 101-10
  17. Bailey DG, Dresser GR, Kreeft JH, Munoz C, Freeman DJ, Bend JR "Grapefruit-felodipine interaction: Effect of unprocessed fruit and probable active ingredients." Clin Pharmacol Ther 68 (2000): 468-77
View all 17 references

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Moderate

iron polysaccharide food

Applies to: Rexavite 150 (ascorbic acid/iron polysaccharide)

ADJUST DOSING INTERVAL: Concomitant use of some oral medications may reduce the bioavailability of orally administered iron, and vice versa.

Food taken in conjunction with oral iron supplements may reduce the bioavailability of the iron. However, in many patients intolerable gastrointestinal side effects occur necessitating administration with food.

MANAGEMENT: Ideally, iron products should be taken on an empty stomach (i.e., at least 1 hour before or 2 hours after meals), but if this is not possible, administer with meals and monitor the patient more closely for a subtherapeutic effect. Some studies suggest administration of iron with ascorbic acid may enhance bioavailability. In addition, administration of oral iron products and some oral medications should be separated whenever the bioavailability of either agent may be decreased. Consult the product labeling for specific separation times and monitor clinical responses as appropriate.

References

  1. "Product Information. Feosol (ferrous sulfate)." SmithKline Beecham PROD
  2. "Product Information. Accrufer (ferric maltol)." Shield Therapeutics (2021):

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Moderate

pseudoephedrine food

Applies to: pseudoephedrine / terfenadine

MONITOR: Coadministration of two or more sympathomimetic agents may increase the risk of adverse effects such as nervousness, irritability, and increased heart rate. Central nervous system (CNS) stimulants, particularly amphetamines, can potentiate the adrenergic response to vasopressors and other sympathomimetic agents. Additive increases in blood pressure and heart rate may occur due to enhanced peripheral sympathetic activity.

MANAGEMENT: Caution is advised if two or more sympathomimetic agents are coadministered. Pulse and blood pressure should be closely monitored.

References

  1. Rosenblatt JE, Lake CR, van Kammen DP, Ziegler MG, Bunney WE Jr "Interactions of amphetamine, pimozide, and lithium on plasma norepineophrine and dopamine-beta-hydroxylase in schizophrenic patients." Psychiatry Res 1 (1979): 45-52
  2. Cavanaugh JH, Griffith JD, Oates JA "Effect of amphetamine on the pressor response to tyramine: formation of p-hydroxynorephedrine from amphetamine in man." Clin Pharmacol Ther 11 (1970): 656
  3. "Product Information. Adderall (amphetamine-dextroamphetamine)." Shire Richwood Pharmaceutical Company Inc PROD (2001):
  4. "Product Information. Tenuate (diethylpropion)." Aventis Pharmaceuticals PROD (2001):
  5. "Product Information. Sanorex (mazindol)." Novartis Pharmaceuticals PROD (2001):
  6. "Product Information. Focalin (dexmethylphenidate)." Mikart Inc (2001):
  7. "Product Information. Strattera (atomoxetine)." Lilly, Eli and Company (2002):
View all 7 references

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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.

See also

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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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