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6 Interactions found for:

allopurinol and Metoprolol Succinate ER
Interactions Summary
  • 4 Major
  • 2 Moderate
  • 0 Minor
  • allopurinol
  • Metoprolol Succinate ER

Drug Interactions

No drug interactions were found for selected drugs: allopurinol, Metoprolol Succinate ER.

This does not necessarily mean no interactions exist. Always consult your healthcare provider.

Drug and Food Interactions

Moderate
Allopurinol + Food

The following applies to the ingredients: Allopurinol

ADJUST DOSING INTERVAL: The tolerability of allopurinol may be improved by giving it after a meal. Additionally, when the dose is greater than 300 mg, dividing the total daily dose into smaller doses administered more often may be appropriate to help minimize gastrointestinal irritation.

MONITOR: Concomitant use of allopurinol with central nervous system (CNS) depressants, including alcohol, may potentiate adverse effects such as somnolence and sedation.

MANAGEMENT: To improve tolerability, some manufacturers suggest administering allopurinol after a meal. Additionally, if the daily dose is greater than 300 mg, administering allopurinol in divided doses may help reduce gastrointestinal intolerance. Patients should also be counseled to avoid or limit consumption of alcohol and to avoid activities requiring mental alertness such as driving or operating hazardous machinery until they know how the medication affects them.

References

  1. "Product Information. Allopurinol (Sandoz) (allopurinol)." Sandoz Pty Ltd (2024):
  2. "Product Information. Zyloric (allopurinol)." Aspen Pharma Trading Ltd (2021):
  3. "Product Information. Zyloprim (allopurinol)." AA Pharma Inc 248178 (2021):
  4. "Product Information. Allopurinol (allopurinol)." Actavis U.S. (Purepac Pharmaceutical Company) (2024):

Moderate
Metoprolol Succinate Er + Food

The following applies to the ingredients: Metoprolol (found in Metoprolol Succinate Er)

ADJUST DOSING INTERVAL: The bioavailability of metoprolol may be enhanced by food.

MANAGEMENT: Patients may be instructed to take metoprolol at the same time each day, preferably with or immediately following meals.

References

  1. "Product Information. Lopressor (metoprolol)." Novartis Pharmaceuticals PROD (2001):
  2. Darcy PF "Nutrient-drug interactions." Adverse Drug React Toxicol Rev 14 (1995): 233-54

The following applies to the ingredients: Metoprolol (found in Metoprolol Succinate Er)

ADJUST DOSING INTERVAL: Concurrent administration with calcium salts may decrease the oral bioavailability of atenolol and possibly other beta-blockers. The exact mechanism of interaction is unknown. In six healthy subjects, calcium 500 mg (as lactate, carbonate, and gluconate) reduced the mean peak plasma concentration (Cmax) and area under the concentration-time curve (AUC) of atenolol (100 mg) by 51% and 32%, respectively. The elimination half-life increased by 44%. Twelve hours after the combination, beta-blocking activity (as indicated by inhibition of exercise tachycardia) was reduced compared to that with atenolol alone. However, during a 4-week treatment in six hypertensive patients, there was no difference in blood pressure values between treatments. The investigators suggest that prolongation of the elimination half-life induced by calcium coadministration may have led to atenolol cumulation during long-term dosing, which compensated for the reduced bioavailability.

MANAGEMENT: It may help to separate the administration times of beta-blockers and calcium products by at least 2 hours. Patients should be monitored for potentially diminished beta-blocking effects following the addition of calcium therapy.

References

  1. Kirch W, Schafer-Korting M, Axthelm T, Kohler H, Mutschler E "Interaction of atenolol with furosemide and calcium and aluminum salts." Clin Pharmacol Ther 30 (1981): 429-35

Drug and Pregnancy Interactions

The following applies to the ingredients: Allopurinol

Safety has not been established.
-According to some authorities: This drug is only recommended for use during pregnancy when there are no safer alternatives and the benefit outweighs the risk.

AU TGA pregnancy category: B2
US FDA pregnancy category: Not assigned

Risk Summary: Based on findings in animals, this drug may cause fetal harm.

Comments:
-Animals exposed to this drug have shown negative developmental effects.
-Placental transfer of this drug and its metabolite have been reported.
-The available data on the use of this drug during pregnancy is limited and inconclusive. Pregnant women should be apprised of the potential risk to the fetus.
-This drug has been used widely for many years without apparent harmful effects.
-Infertility and impotence in men rarely occur during treatment with this drug, and studies have not confirmed an association with it.

Animal studies have failed to reveal evidence of fetotoxicity or teratogenicity. However, intraperitoneal administration of this drug in pregnant mice on gestation days 10 or 13 produced significant increases in fetal deaths and teratogenic effects (cleft palate, harelip, and digital defects). In another study, this drug after oral administration to pregnant rats during organogenesis caused embryonic resorptions, growth retardation, decreased fetal weight, and skeletal, liver, kidney, and brain abnormalities. A 2013 report analyzed 31 pregnancies exposed to this drug during the first trimester, finding that major birth defects and miscarriages were within the general population's range, but one child had severe defects. There is insufficient data in human pregnancy.

AU TGA pregnancy category B2: Drugs which have been taken by only a limited number of pregnant women and women of childbearing age, without an increase in the frequency of malformation or other direct or indirect harmful effects on the human fetus having been observed. Studies in animals are inadequate or may be lacking, but available data show no evidence of an increased occurrence of fetal damage.

US FDA pregnancy category Not Assigned: The US FDA has amended the pregnancy labeling rule for prescription drug products to require labeling that includes a summary of risk, a discussion of the data supporting that summary, and relevant information to help health care providers make prescribing decisions and counsel women about the use of drugs during pregnancy. Pregnancy categories A, B, C, D, and X are being phased out.

References

  1. "Product Information. Allosig (allopurinol)." Arrow Pharma Pty Ltd 18 March 2025 (2025):
  2. "Product Information. Zyloric (allopurinol)." Aspen Pharma Trading Ltd 19 Feb 2025 (2025):
  3. "Product Information. Aloprim (allopurinol)." Mylan Institutional LLC 2/2022 (2022):
  4. "Product Information. Zyloprim (allopurinol)." Casper Pharma LLC 9/2023 (2023):
  5. "Product Information. Allopurinol (allopurinol)." Leading Pharma, LLC 9/2024 (2024):

The following applies to the ingredients: Metoprolol (found in Metoprolol Succinate Er)

Safety has not been established during pregnancy.
-According to some authorities: Use is not recommended unless benefit outweighs risk; if used during pregnancy, administer the lowest possible dose and discontinue at least 2 to 3 days prior to expected delivery, if possible.


AU TGA pregnancy category: C
US FDA pregnancy category: Not assigned

Risk summary: Inconclusive data available on the use of this drug in pregnant women to inform a drug-related risk.

Comments:
-Based on published literature, this drug may cause erectile dysfunction and inhibit sperm motility.

Animal studies have revealed increased post-implantation loss, fetolethality, and decreased neonatal survival. This drug crosses placenta, neonates born to mothers who are receiving metoprolol during pregnancy, may be at risk for hypotension, hypoglycemia, bradycardia, and respiratory depression.

AU TGA pregnancy category C: Drugs which, owing to their pharmacological effects, have caused or may be suspected of causing, harmful effects on the human fetus or neonate without causing malformations. These effects may be reversible. Accompanying texts should be consulted for further details.

US FDA pregnancy category Not Assigned: The US FDA has amended the pregnancy labeling rule for prescription drug products to require labeling that includes a summary of risk, a discussion of the data supporting that summary, and relevant information to help health care providers make prescribing decisions and counsel women about the use of drugs during pregnancy. Pregnancy categories A, B, C, D, and X are being phased out.

References

  1. "Product Information. Lopressor (metoprolol)." Novartis Pharmaceuticals PROD (2001):
  2. Cerner Multum, Inc. "UK Summary of Product Characteristics." O 0
  3. Cerner Multum, Inc. "Australian Product Information." O 0
  4. "Product Information. Kapspargo Sprinkle (metoprolol)." Sun Pharmaceutical Industries (2023):
  5. "Product Information. Toprol-XL (metoprolol)." Melinta Therapeutics, Inc. (2023):
  6. "Product Information. Lopressor (metoprolol)." Validus Pharmaceuticals LLC (2025):
  7. "Product Information. Metoprolol Tartrate (metoprolol)." Hikma USA (formerly West-Ward Pharmaceutical Corporation) (2025):

Drug and Breastfeeding Interactions

The following applies to the ingredients: Allopurinol

Breastfeeding is not recommended during use of this drug and for 1 week after the last dose.

Excreted into human milk: Yes

Comments:
-This drug and its active metabolite were detected in human milk.
-There was no report of effects of this drug on the nursing infant or on milk production.
-If the mother requires this drug, she does not have to stop nursing, but the nursing infant should be monitored for allergic reactions (such as rash) and undergo periodic CBC and differential blood counts.

References

  1. Bethesda (MD): National Institute of Child Health and Human Development (US) "Allopurinol - Drugs and Lactation Database (LactMed) https://www.ncbi.nlm.nih.gov/books/NBK501198/" (2025):
  2. "Product Information. Allosig (allopurinol)." Arrow Pharma Pty Ltd 18 March 2025 (2025):
  3. "Product Information. Zyloric (allopurinol)." Aspen Pharma Trading Ltd 19 Feb 2025 (2025):
  4. "Product Information. Aloprim (allopurinol)." Mylan Institutional LLC 2/2022 (2022):
  5. "Product Information. Zyloprim (allopurinol)." Casper Pharma LLC 9/2023 (2023):
  6. "Product Information. Allopurinol (allopurinol)." Leading Pharma, LLC 9/2024 (2024):

The following applies to the ingredients: Metoprolol (found in Metoprolol Succinate Er)

AU and UK: Use is not recommended unless benefit outweighs risk.
US: This drug has been used without apparent harmful effects; caution is recommended.

Excreted into human milk: Yes (in small amounts)

Comments: This drug has been used without apparent harmful effects in the nursing infant.

An infant consuming 1 L of breast milk a day would receive a dose of less than 1 mg of drug.

References

  1. "Product Information. Lopressor (metoprolol)." Novartis Pharmaceuticals PROD (2001):
  2. Cerner Multum, Inc. "UK Summary of Product Characteristics." O 0
  3. Cerner Multum, Inc. "Australian Product Information." O 0

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.

Switch to: Consumer Interactions

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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