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Drug Interaction Report

4 potential interactions and/or warnings found for the following 2 drugs:

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Interactions between your drugs

Moderate

doxycycline multivitamin, prenatal

Applies to: Doxy 100 (doxycycline), Natatab CFe (multivitamin, prenatal)

GENERALLY AVOID: The bioavailability of oral tetracyclines and iron salts may be significantly decreased during concurrent administration. Therapeutic failure may result. The proposed mechanism is chelation of tetracyclines by the iron cation, forming an insoluble complex that is poorly absorbed from the gastrointestinal tract. In ten healthy volunteers, simultaneous oral administration of ferrous sulfate 200 mg and single doses of various tetracyclines (200 mg to 500 mg) resulted in reductions in the serum levels of methacycline and doxycycline by 80% to 90%, oxytetracycline by 50% to 60%, and tetracycline by 40% to 50%. In another study, 300 mg of ferrous sulfate reduced the absorption of tetracycline by 81% and that of minocycline by 77%. Conversely, the absorption of iron has been shown to be decreased by up to 78% in healthy subjects and up to 65% in patients with iron depletion when ferrous sulfate 250 mg was administered with tetracycline 500 mg. Available data suggest that administration of iron 3 hours before or 2 hours after a tetracycline largely prevents the interaction with most tetracyclines except doxycycline. Due to extensive enterohepatic cycling, iron binding may occur with doxycycline even when it is given parenterally. It has also been shown that when iron is administered up to 11 hours after doxycycline, serum concentrations of doxycycline may still be reduced by 20% to 45%.

MANAGEMENT: Coadministration of a tetracycline with any iron-containing product should be avoided if possible. Otherwise, patients should be advised to stagger the times of administration by at least three to four hours, although separating the doses may not prevent the interaction with doxycycline.

References

  1. Neuvonen PJ (1976) "Interactions with the absorption of tetracyclines." Drugs, 11, p. 45-54
  2. Gothoni G, Neuvonen PJ, Mattila M, Hackman R (1972) "Iron-tetracycline interaction: effect of time interval between the drugs." Acta Med Scand, 191, p. 409-11
  3. Venho VM, Salonen RO, Mattila MJ (1978) "Modification of the pharmacokinetics of doxycycline in man by ferrous sulphate or charcoal." Eur J Clin Pharmacol, 14, p. 277-80
  4. (2002) "Product Information. Minocin (minocycline)." Lederle Laboratories
  5. Campbell NR, Hasinoff BB (1991) "Iron supplements: a common cause of drug interactions." Br J Clin Pharmacol, 31, p. 251-5
  6. Bateman FJ (1970) "Effects of tetracyclines." Br Med J, 4, p. 802
  7. Neuvonen PJ, Gothoni G, Hackman R, Bjorksten K (1970) "Interference of iron with the absorption of tetracyclines in man." Br Med J, 4, p. 532-4
  8. Greenberger NJ (1971) "Absorption of tetracyclines: interference by iron." Ann Intern Med, 74, p. 792-3
  9. Neuvonen PJ, Penttila O (1974) "Effect of oral ferrous sulphate on the half-life of doxycycline in man." Eur J Clin Pharmacol, 7, p. 361-3
  10. (2018) "Product Information. Seysara (sarecycline)." Allergan Inc
  11. (2018) "Product Information. Nuzyra (omadacycline)." Paratek Pharmaceuticals, Inc.
View all 11 references

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Drug and food interactions

Moderate

multivitamin, prenatal food

Applies to: Natatab CFe (multivitamin, prenatal)

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
  2. (2021) "Product Information. Accrufer (ferric maltol)." Shield Therapeutics

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Moderate

doxycycline food

Applies to: Doxy 100 (doxycycline)

GENERALLY AVOID: The bioavailability of oral tetracyclines and iron salts may be significantly decreased during concurrent administration. Therapeutic failure may result. The proposed mechanism is chelation of tetracyclines by the iron cation, forming an insoluble complex that is poorly absorbed from the gastrointestinal tract. In ten healthy volunteers, simultaneous oral administration of ferrous sulfate 200 mg and single doses of various tetracyclines (200 mg to 500 mg) resulted in reductions in the serum levels of methacycline and doxycycline by 80% to 90%, oxytetracycline by 50% to 60%, and tetracycline by 40% to 50%. In another study, 300 mg of ferrous sulfate reduced the absorption of tetracycline by 81% and that of minocycline by 77%. Conversely, the absorption of iron has been shown to be decreased by up to 78% in healthy subjects and up to 65% in patients with iron depletion when ferrous sulfate 250 mg was administered with tetracycline 500 mg. Available data suggest that administration of iron 3 hours before or 2 hours after a tetracycline largely prevents the interaction with most tetracyclines except doxycycline. Due to extensive enterohepatic cycling, iron binding may occur with doxycycline even when it is given parenterally. It has also been shown that when iron is administered up to 11 hours after doxycycline, serum concentrations of doxycycline may still be reduced by 20% to 45%.

MANAGEMENT: Coadministration of a tetracycline with any iron-containing product should be avoided if possible. Otherwise, patients should be advised to stagger the times of administration by at least three to four hours, although separating the doses may not prevent the interaction with doxycycline.

References

  1. Neuvonen PJ (1976) "Interactions with the absorption of tetracyclines." Drugs, 11, p. 45-54
  2. Gothoni G, Neuvonen PJ, Mattila M, Hackman R (1972) "Iron-tetracycline interaction: effect of time interval between the drugs." Acta Med Scand, 191, p. 409-11
  3. Venho VM, Salonen RO, Mattila MJ (1978) "Modification of the pharmacokinetics of doxycycline in man by ferrous sulphate or charcoal." Eur J Clin Pharmacol, 14, p. 277-80
  4. (2002) "Product Information. Minocin (minocycline)." Lederle Laboratories
  5. Campbell NR, Hasinoff BB (1991) "Iron supplements: a common cause of drug interactions." Br J Clin Pharmacol, 31, p. 251-5
  6. Bateman FJ (1970) "Effects of tetracyclines." Br Med J, 4, p. 802
  7. Neuvonen PJ, Gothoni G, Hackman R, Bjorksten K (1970) "Interference of iron with the absorption of tetracyclines in man." Br Med J, 4, p. 532-4
  8. Greenberger NJ (1971) "Absorption of tetracyclines: interference by iron." Ann Intern Med, 74, p. 792-3
  9. Neuvonen PJ, Penttila O (1974) "Effect of oral ferrous sulphate on the half-life of doxycycline in man." Eur J Clin Pharmacol, 7, p. 361-3
  10. (2018) "Product Information. Seysara (sarecycline)." Allergan Inc
  11. (2018) "Product Information. Nuzyra (omadacycline)." Paratek Pharmaceuticals, Inc.
View all 11 references

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Minor

doxycycline food

Applies to: Doxy 100 (doxycycline)

Chronic alcohol consumption may enhance the elimination of doxycycline. The mechanism is induction of hepatic microsomal enzymes by alcohol. In one study, the half-life of doxycycline in six alcoholics was 10.5 hours, compared with 14.7 hours in six control patients. In addition, half the alcoholic patients had serum concentrations below what is generally considered the minimum therapeutic concentration (0.5 mcg/mL) at 12 to 24 hours after the dose. The investigators suggest that twice-a-day dosing may be indicated in these patients, especially if additional inducing drugs are used. The elimination of other tetracyclines probably is not affected by alcohol consumption.

References

  1. Neuvonen PJ, Penttila O, Roos M, Tirkkonen J (1976) "Effect of long-term alcohol consumption on the half-life of tetracycline and doxycycline in man." Int J Clin Pharmacol Biopharm, 14, p. 303-7

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Therapeutic duplication warnings

No duplication 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.

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Further information

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