6 Interactions found for:
Drug Interactions
No drug interactions were found for selected drugs: allopurinol, Lipitor.
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
- "Product Information. Allopurinol (Sandoz) (allopurinol)." Sandoz Pty Ltd (2024):
- "Product Information. Zyloric (allopurinol)." Aspen Pharma Trading Ltd (2021):
- "Product Information. Zyloprim (allopurinol)." AA Pharma Inc 248178 (2021):
- "Product Information. Allopurinol (allopurinol)." Actavis U.S. (Purepac Pharmaceutical Company) (2024):
Moderate
Lipitor
+ Food
The following applies to the ingredients: Atorvastatin (found in Lipitor)
GENERALLY AVOID: Coadministration with grapefruit juice may increase the plasma concentrations of atorvastatin. The proposed mechanism is inhibition of CYP450 3A4-mediated first-pass metabolism in the gut wall by certain compounds present in grapefruit. When a single 40 mg dose of atorvastatin was coadministered with 240 mL of grapefruit juice, atorvastatin peak plasma concentration (Cmax) and systemic exposure (AUC) increased by 16% and 37%, respectively. Greater increases in Cmax (up to 71%) and/or AUC (up to 2.5 fold) have been reported with excessive consumption of grapefruit juice (>=750 mL to 1.2 liters per day). Clinically, high levels of HMG-CoA reductase inhibitory activity in plasma is associated with an increased risk of musculoskeletal toxicity. Myopathy manifested as muscle pain and/or weakness associated with grossly elevated creatine kinase exceeding ten times the upper limit of normal has been reported occasionally. Rhabdomyolysis has also occurred rarely, which may be accompanied by acute renal failure secondary to myoglobinuria and may result in death.
ADJUST DOSING INTERVAL: Fibres such as oat bran and pectin may diminish the pharmacologic effects of HMG-CoA reductase inhibitors by interfering with their absorption from the gastrointestinal tract.
MANAGEMENT: Patients receiving therapy with atorvastatin should limit their consumption of grapefruit juice to no more than 1 liter per day. Patients should be advised to promptly report any unexplained muscle pain, tenderness or weakness, particularly if accompanied by fever, malaise and/or dark colored urine. Therapy should be discontinued if creatine kinase is markedly elevated in the absence of strenuous exercise or if myopathy is otherwise suspected or diagnosed. In addition, patients should either refrain from the use of oat bran and pectin or, if concurrent use cannot be avoided, to separate the administration times by at least 2 to 4 hours.
References
- Richter WO, Jacob BG, Schwandt P "Interaction between fibre and lovastatin." Lancet 338 (1991): 706
- McMillan K "Considerations in the formulary selection of hydroxymethylglutaryl coenzyme a reductase inhibitors." Am J Health Syst Pharm 53 (1996): 2206-14
- "Product Information. Lipitor (atorvastatin)." Parke-Davis PROD (2001):
- Boberg M, Angerbauer R, Fey P, Kanhai WK, Karl W, Kern A, Ploschke J, Radtke M "Metabolism of cerivastatin by human liver microsomes in vitro. Characterization of primary metabolic pathways and of cytochrome P45 isozymes involved." Drug Metab Dispos 25 (1997): 321-31
- Bailey DG, Malcolm J, Arnold O, Spence JD "Grapefruit juice-drug interactions." Br J Clin Pharmacol 46 (1998): 101-10
- Lilja JJ, Kivisto KT, Neuvonen PJ "Grapefruit juice increases serum concentrations of atorvastatin and has no effect on pravastatin." Clin Pharmacol Ther 66 (1999): 118-27
- Neuvonen PJ, Backman JT, Niemi M "Pharmacokinetic comparison of the potential over-the-counter statins simvastatin, lovastatin, fluvastatin and pravastatin." Clin Pharmacokinet 47 (2008): 463-74
Drug and Pregnancy Interactions
Major
Allopurinol
+ Pregnancy
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
- "Product Information. Allosig (allopurinol)." Arrow Pharma Pty Ltd 18 March 2025 (2025):
- "Product Information. Zyloric (allopurinol)." Aspen Pharma Trading Ltd 19 Feb 2025 (2025):
- "Product Information. Aloprim (allopurinol)." Mylan Institutional LLC 2/2022 (2022):
- "Product Information. Zyloprim (allopurinol)." Casper Pharma LLC 9/2023 (2023):
- "Product Information. Allopurinol (allopurinol)." Leading Pharma, LLC 9/2024 (2024):
Major
Lipitor
+ Pregnancy
The following applies to the ingredients: Atorvastatin (found in Lipitor)
According to some authorities: Use is contraindicated during pregnancy or in patients of childbearing potential not using contraception.
AU TGA pregnancy category: D
US FDA pregnancy category: Not assigned
Risk summary: Based on its mechanism of action, this drug may cause fetal harm when administered during pregnancy.
-Available data on the use of statins in pregnant women have not identified a drug-related risk of major congenital malformations and are insufficient to inform a drug-related risk of miscarriage.
Comments:
-If the patient becomes pregnant while taking this drug, therapy should be discontinued and the patient should be apprised of the potential harm to the fetus.
---According to some authorities: Alternatively, the ongoing needs of the individual patient should be considered.
-According to some authorities: Patients of childbearing potential should use effective contraception during therapy; this drug should be used in patients of childbearing potential only when they are highly unlikely to conceive and have been informed of the potential.
Animal studies have failed to reveal evidence of embryofetal toxicity or teratogenicity; however, at maternally toxic doses, increased postimplantation loss and decreased fetal body weights have been observed. No adverse developmental effects were observed in pregnant rats or rabbits administered oral doses that resulted in up to 30 and 20 times, respectively, the human exposure at the maximum recommended human dose (MRHD) of 80 mg (based on body surface area [mg/m2]); in rats administered this drug during gestation and lactation, decreased postnatal growth and development delay were observed at doses at least 6 times the MRHD. This drug crosses the rat placenta and reaches levels in the fetal liver equivalent to that of maternal plasma. A study of statin-exposed pregnant women compared to controls did not find a significant teratogenic effect from maternal use of statins in the first trimester, after adjusting for potential confounders. Rare cases of congenital anomalies after intrauterine exposure to HMG-CoA reductase inhibitors have been reported. There are no controlled data in human pregnancy.
Cholesterol and other products of cholesterol biosynthesis are essential components for fetal development (including synthesis of steroids and cell membranes). Because this drug decreases synthesis of cholesterol and possibly other biologically active substances derived from cholesterol, it may cause fetal harm when used during pregnancy.
Treatment of hyperlipidemia is not generally necessary during pregnancy. Since atherosclerosis is a chronic process, discontinuation of lipid-lowering drugs during pregnancy should have little impact on the outcome of long-term primary hypercholesterolemia therapy for most patients.
AU TGA pregnancy category D: Drugs which have caused, are suspected to have caused or may be expected to cause, an increased incidence of human fetal malformations or irreversible damage. These drugs may also have adverse pharmacological effects. 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
- "Product Information. Lipitor (atorvastatin)." Viatris Specialty LLC SUPPL-81 (2024):
- "Product Information. Atorvaliq (atorvastatin)." Carolina Medical Products Company SUPPL-2 (2024):
- "Product Information. Lipitor (atorvastatin)." Aspen Pharmacare Australia Pty Ltd (2023):
- "Product Information. Lorstat (atorvastatin)." Alphapharm Pty Ltd (2024):
- "Product Information. Lipitor (atorvastatin)." Viatris UK Healthcare Ltd (2024):
- "Product Information. Atorvastatin (atorvastatin)." Rosemont Pharmaceuticals Ltd (2024):
Drug and Breastfeeding Interactions
Major
Allopurinol
+ Breastfeeding
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
- 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):
- "Product Information. Allosig (allopurinol)." Arrow Pharma Pty Ltd 18 March 2025 (2025):
- "Product Information. Zyloric (allopurinol)." Aspen Pharma Trading Ltd 19 Feb 2025 (2025):
- "Product Information. Aloprim (allopurinol)." Mylan Institutional LLC 2/2022 (2022):
- "Product Information. Zyloprim (allopurinol)." Casper Pharma LLC 9/2023 (2023):
- "Product Information. Allopurinol (allopurinol)." Leading Pharma, LLC 9/2024 (2024):
Major
Lipitor
+ Breastfeeding
The following applies to the ingredients: Atorvastatin (found in Lipitor)
Until more data are available, an alternate agent may be preferred, particularly while breastfeeding newborn or preterm infants.
-According to some authorities: Breastfeeding is not recommended during use of this drug.
-According to some authorities: Use is contraindicated.
Excreted into human milk: Unknown
Excreted into animal milk: Yes
Comments:
-Another drug in this class is excreted into human milk.
-Statins (including this drug) decrease synthesis of cholesterol and possibly other biologically active substances derived from cholesterol; they may cause harm to the breastfed infant.
-The effects in the nursing infant are unknown; based on the mechanism of action, there is the potential for serious adverse reactions in nursing infants.
Due to a concern over disruption of infant lipid metabolism, it is generally agreed that women taking a statin should not breastfeed; however, others have argued that children homozygous for familial hypercholesterolemia are treated with statins starting at 1 year of age, statins have low oral bioavailability, and risks to the breastfed infant are low. Some evidence indicates that this drug can be taken by nursing mothers with no obvious developmental problems in their infants.
In cases of patients with homozygous familial hypercholesterolemia, 6 patients breastfed 11 infants after restarting statin therapy postpartum; the specific statin was not reported, but most of the women on statin therapy were using this drug (40 or 80 mg/day). Normal early child development was reported for all offspring; children started school at the appropriate age with no learning difficulties reported.
References
- Bethesda (MD): National Institute of Child Health and Human Development (US) "Atorvastatin - Drugs and Lactation Database (LactMed) https://www.ncbi.nlm.nih.gov/books/NBK501361/" (2024):
- "Product Information. Lipitor (atorvastatin)." Viatris Specialty LLC SUPPL-81 (2024):
- "Product Information. Atorvaliq (atorvastatin)." Carolina Medical Products Company SUPPL-2 (2024):
- "Product Information. Lipitor (atorvastatin)." Aspen Pharmacare Australia Pty Ltd (2023):
- "Product Information. Lorstat (atorvastatin)." Alphapharm Pty Ltd (2024):
- "Product Information. Lipitor (atorvastatin)." Viatris UK Healthcare Ltd (2024):
- "Product Information. Atorvastatin (atorvastatin)." Rosemont Pharmaceuticals Ltd (2024):
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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