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Interactions between Fenfluramine and Lipitor

1 drug interaction and 24 additional warnings found for the following 2 drugs:

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Drug interactions

Moderate drug interactions

Moderate:

fenfluramine atorvastatin

Applies to: fenfluramine and Lipitor (atorvastatin)
Monitor

Coadministration with fenfluramine may decrease the plasma concentrations and therapeutic efficacy of drugs that are substrates of the CYP450 2B6 and/or CYP450 3A4 isoenzymes. The proposed mechanism, based on in vitro data, might be increased clearance due to induction of CYP450 2B6 and intestinal CYP450 3A4.

Management

Caution and monitoring are recommended if fenfluramine is used concomitantly with drugs that are substrates of CYP450 2B6 and/or CYP450 3A4, particularly sensitive substrates or those with a narrow therapeutic range. Monitoring for potential loss of therapeutic efficacy is recommended. The prescribing information for concomitant medications may be consulted to assess the benefits versus risks of coadministration, as well as any dosage adjustments that may be required during coadministration and/or following the discontinuation of a CYP450 2B6 and/or CYP450 3A4 inducer.

References (3)
  1. (2023) "Product Information. Fintepla (fenfluramine)." UCB Pharma Ltd, SUPPL-13
  2. (2024) "Product Information. Fintepla (fenfluramine)." UCB Australia Pty Ltd T/A UCB Pharma Division of UCB Australia
  3. (2023) "Product Information. Fintepla (fenfluramine)." Prescript Pharmaceuticals, SUPPL-13

Food/lifestyle interactions

Moderate food/lifestyle interactions

Moderate:

fenfluramine Food/Lifestyle

Applies to: fenfluramine
Generally avoid

Alcohol may potentiate the central nervous system and cardiovascular effects of centrally-acting appetite suppressants. In one study, concurrent administration of methamphetamine (30 mg intravenously) and ethanol (1 gm/kg orally over 30 minutes) increased heart rate by 24 beats/minute compared to methamphetamine alone. This increases cardiac work and myocardial oxygen consumption, which may lead to more adverse cardiovascular effects than either agent alone. Subjective effects of ethanol were diminished in the eight study subjects, but those of methamphetamine were not affected. The pharmacokinetics of methamphetamine were also unaffected except for a decrease in the apparent volume of distribution at steady state.

Management

Concomitant use of centrally-acting appetite suppressants and alcohol should be avoided if possible, especially in patients with a history of cardiovascular disease. Patients should be counselled to avoid hazardous activities requiring complete mental alertness and motor coordination until they know how these agents affect them, and to notify their physician if they experience excessive or prolonged CNS effects that interfere with their normal activities.

References (3)
  1. Mendelson J, Jones RT, Upton R, Jacob P 3rd (1995) "Methamphetamine and ethanol interactions in humans." Clin Pharmacol Ther, 57, p. 559-68
  2. (2001) "Product Information. Didrex (benzphetamine)." Pharmacia and Upjohn
  3. (2012) "Product Information. Suprenza (phentermine)." Akrimax Pharmaceuticals
Moderate:

atorvastatin Food/Lifestyle

Applies to: Lipitor (atorvastatin)
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 (7)
  1. Richter WO, Jacob BG, Schwandt P (1991) "Interaction between fibre and lovastatin." Lancet, 338, p. 706
  2. McMillan K (1996) "Considerations in the formulary selection of hydroxymethylglutaryl coenzyme a reductase inhibitors." Am J Health Syst Pharm, 53, p. 2206-14
  3. (2001) "Product Information. Lipitor (atorvastatin)." Parke-Davis
  4. Boberg M, Angerbauer R, Fey P, Kanhai WK, Karl W, Kern A, Ploschke J, Radtke M (1997) "Metabolism of cerivastatin by human liver microsomes in vitro. Characterization of primary metabolic pathways and of cytochrome P45 isozymes involved." Drug Metab Dispos, 25, p. 321-31
  5. Bailey DG, Malcolm J, Arnold O, Spence JD (1998) "Grapefruit juice-drug interactions." Br J Clin Pharmacol, 46, p. 101-10
  6. Lilja JJ, Kivisto KT, Neuvonen PJ (1999) "Grapefruit juice increases serum concentrations of atorvastatin and has no effect on pravastatin." Clin Pharmacol Ther, 66, p. 118-27
  7. Neuvonen PJ, Backman JT, Niemi M (2008) "Pharmacokinetic comparison of the potential over-the-counter statins simvastatin, lovastatin, fluvastatin and pravastatin." Clin Pharmacokinet, 47, p. 463-74

Disease interactions

22 potential interactions Applies to: 16 conditions, including High Blood Pressure, Depression, Underactive Thyroid, Pulmonary Arterial Hypertension, and Psychosis.

Alcoholism

Major:

Lipitor

The atorvastatin in Lipitor has a major potential interaction with Alcoholism.

The use of most HMG-CoA reductase inhibitors is contraindicated in patients with active liver disease, decompensated cirrhosis, or unexplained persistent elevations of serum transaminases. HMG-CoA reductase inhibitors are extensively metabolized by the liver. Decreased drug metabolism may lead to accumulation and increased risk of toxicity, including biochemical abnormalities of liver function and, rarely, jaundice, hepatitis, cirrhosis, fatty change in the liver, and fulminant hepatic necrosis. Therapy with HMG-CoA reductase inhibitors should be administered cautiously in patients with a history of liver disease and/or heavy alcohol use. A lower initial dosage may be appropriate, and clinical monitoring of liver transaminase levels according to the individual manufacturer product information is recommended. Patients who develop elevated ALT or AST levels during therapy should be monitored until abnormalities resolve. If an increase above 3 times the upper limit of normal persists, consideration should be given to a reduction in dosage or withdrawal of therapy.

Moderate:

fenfluramine

Fenfluramine has a moderate potential interaction with Alcoholism.

Fenfluramine can cause somnolence, sedation, and lethargy. Central nervous system depressants, including alcohol, could potentiate these effects. Exercise caution when using this agent in alcoholic patients or those at risk of sedation. Close monitoring is advised. Advise patients not to drive or operate machinery until they know how this drug will affect them.

Central Nervous System Disorders

Moderate:

Lipitor

The atorvastatin in Lipitor has a moderate potential interaction with Central Nervous System Disorders.

Cognitive impairment (e.g., memory loss, forgetfulness, amnesia, memory impairment, confusion) have been observed in patients receiving statins. The reports are usually not serious, and reversible upon statin discontinuation. Caution is recommended when using these agents in patients with cognitive impairment.

Depression

Major:

fenfluramine

Fenfluramine has a major potential interaction with Depression.

The use of CNS stimulants can cause psychotic symptoms, suicidal ideation, and aggression, and can exacerbate symptoms of behavior disturbance and thought disorder; CNS stimulants may induce a manic or mixed episode in patients with bipolar disorder. Psychiatric symptoms have been reported in patients with and without history of psychiatric disorders. All patients (particularly those with psychotic or bipolar disorders) should be monitored closely, especially during treatment initiation and at times of dose changes. Extreme caution should be exercised when CNS stimulants are given to patients with a history of psychosis, depression, mania, or bipolar disorder. Prior to initiating therapy, all patients should be screened for risk factors for developing a manic episode (e.g., comorbid or history of depressive symptoms or family history of suicide, bipolar disease, or depression). If any psychiatric symptoms emerge or are exacerbated, treatment suspension should be considered. Some CNS stimulants are contraindicated in patients with marked agitation or anxiety.

Moderate:

fenfluramine

Fenfluramine has a moderate potential interaction with Depression.

Antiepileptic drugs (AEDs) have been associated with an increased risk of suicidal thoughts or behavior in patients taking these drugs for any indication. Pooled analyses of 199 placebo-controlled clinical studies involving the use of 11 different AEDs showed that patients receiving AEDs had approximately twice the risk of suicidal thinking or behavior compared to patients receiving placebo. AEDs should be administered cautiously in patients with depression or other psychiatric disorders; phentermine-topiramate should be avoided in patients with history of suicidal attempts or active suicidal ideation. The risk of suicidal thoughts and behavior should be carefully assessed against the risk of untreated illness, bearing in mind that epilepsy and many other conditions for which AEDs are prescribed are themselves associated with morbidity and mortality and an increased risk of suicidal thoughts and behavior. Patients, caregivers, and families should be alert to the emergence or worsening of signs and symptoms of depression, any unusual changes in mood or behavior, or the emergence of suicidal thoughts or behavior. If patients have symptoms of suicidal ideation or behavior, a dosage reduction or treatment discontinuation should be considered.

Diabetes Mellitus

Moderate:

Lipitor

The atorvastatin in Lipitor has a moderate potential interaction with Diabetes Mellitus.

Increases in hemoglobin A1c and fasting serum glucose levels have been reported with the use of certain HMG-CoA reductase inhibitors. Caution should be exercised when using these agents in diabetic patients and close monitoring is recommended.

Failure to Thrive

Moderate:

fenfluramine

Fenfluramine has a moderate potential interaction with Failure to Thrive.

Fenfluramine can cause decreases in appetite and weight. Exercise care when using this agent in patients at risk of decreased appetite or weight. It is recommended to monitor the growth of pediatric patients carefully. Weight should be monitored regularly during treatment, and dose modifications should be considered if a decrease in weight is observed.

High Blood Pressure

Moderate:

fenfluramine

Fenfluramine has a moderate potential interaction with High Blood Pressure.

Fenfluramine can cause an increase in blood pressure. Exercise care when using this agent in hypertensive patients. It is recommended to monitor blood pressure in patients treated with fenfluramine.

Liver Disease

Major:

Lipitor

The atorvastatin in Lipitor has a major potential interaction with Liver Disease.

The use of most HMG-CoA reductase inhibitors is contraindicated in patients with active liver disease, decompensated cirrhosis, or unexplained persistent elevations of serum transaminases. HMG-CoA reductase inhibitors are extensively metabolized by the liver. Decreased drug metabolism may lead to accumulation and increased risk of toxicity, including biochemical abnormalities of liver function and, rarely, jaundice, hepatitis, cirrhosis, fatty change in the liver, and fulminant hepatic necrosis. Therapy with HMG-CoA reductase inhibitors should be administered cautiously in patients with a history of liver disease and/or heavy alcohol use. A lower initial dosage may be appropriate, and clinical monitoring of liver transaminase levels according to the individual manufacturer product information is recommended. Patients who develop elevated ALT or AST levels during therapy should be monitored until abnormalities resolve. If an increase above 3 times the upper limit of normal persists, consideration should be given to a reduction in dosage or withdrawal of therapy.

Moderate:

fenfluramine

Fenfluramine has a moderate potential interaction with Liver Disease.

Fenfluramine is primarily metabolized to norfenfluramine in the liver. The maximum daily dosage of 20 mg per day should not be exceeded in patients with mild and moderate liver dysfunction. Patients with severe liver dysfunction should not exceed 17 mg per day. The manufacturer prescribing information should be consulted for dose adjustment information of fenfluramine with other concomitant antiepileptic drugs.

Malnourishment

Moderate:

fenfluramine

Fenfluramine has a moderate potential interaction with Malnourishment.

Fenfluramine can cause decreases in appetite and weight. Exercise care when using this agent in patients at risk of decreased appetite or weight. It is recommended to monitor the growth of pediatric patients carefully. Weight should be monitored regularly during treatment, and dose modifications should be considered if a decrease in weight is observed.

Myoneural Disorder

Moderate:

Lipitor

The atorvastatin in Lipitor has a moderate potential interaction with Myoneural Disorder.

HMG-CoA reductase inhibitors may cause myopathy and rhabdomyolysis; acute renal failure secondary to myoglobinuria and rare fatalities have occurred due to rhabdomyolysis in patients treated with statins. The myopathy may be dose-related and is characterized by unexplained muscle weakness, pain, or tenderness accompanied by increases in creatine phosphokinase (CPK) values exceeding 10 times the upper limit of normal. Therapy with HMG-CoA reductase inhibitors should be administered cautiously in patients with preexisting myopathy, in those with predisposing factors for myopathy, or with a history of myoneural disorder, since it may delay the recognition or confound the diagnosis of a drug-induced musculoskeletal effect. Patients should be advised to report promptly any unusual muscle pain, tenderness, or weakness, particularly if accompanied by malaise or fever. Periodic CPK determinations may be considered in some patients, although the value of such monitoring is uncertain. HMG-CoA reductase inhibitor therapy should be withdrawn if markedly elevated CPK levels occur or if drug-related myopathy is diagnosed or suspected.

Myopathy

Moderate:

Lipitor

The atorvastatin in Lipitor has a moderate potential interaction with Myopathy.

HMG-CoA reductase inhibitors may cause myopathy and rhabdomyolysis; acute renal failure secondary to myoglobinuria and rare fatalities have occurred due to rhabdomyolysis in patients treated with statins. The myopathy may be dose-related and is characterized by unexplained muscle weakness, pain, or tenderness accompanied by increases in creatine phosphokinase (CPK) values exceeding 10 times the upper limit of normal. Therapy with HMG-CoA reductase inhibitors should be administered cautiously in patients with preexisting myopathy, in those with predisposing factors for myopathy, or with a history of myoneural disorder, since it may delay the recognition or confound the diagnosis of a drug-induced musculoskeletal effect. Patients should be advised to report promptly any unusual muscle pain, tenderness, or weakness, particularly if accompanied by malaise or fever. Periodic CPK determinations may be considered in some patients, although the value of such monitoring is uncertain. HMG-CoA reductase inhibitor therapy should be withdrawn if markedly elevated CPK levels occur or if drug-related myopathy is diagnosed or suspected.

Psychosis

Major:

fenfluramine

Fenfluramine has a major potential interaction with Psychosis.

The use of CNS stimulants can cause psychotic symptoms, suicidal ideation, and aggression, and can exacerbate symptoms of behavior disturbance and thought disorder; CNS stimulants may induce a manic or mixed episode in patients with bipolar disorder. Psychiatric symptoms have been reported in patients with and without history of psychiatric disorders. All patients (particularly those with psychotic or bipolar disorders) should be monitored closely, especially during treatment initiation and at times of dose changes. Extreme caution should be exercised when CNS stimulants are given to patients with a history of psychosis, depression, mania, or bipolar disorder. Prior to initiating therapy, all patients should be screened for risk factors for developing a manic episode (e.g., comorbid or history of depressive symptoms or family history of suicide, bipolar disease, or depression). If any psychiatric symptoms emerge or are exacerbated, treatment suspension should be considered. Some CNS stimulants are contraindicated in patients with marked agitation or anxiety.

Moderate:

fenfluramine

Fenfluramine has a moderate potential interaction with Psychosis.

Antiepileptic drugs (AEDs) have been associated with an increased risk of suicidal thoughts or behavior in patients taking these drugs for any indication. Pooled analyses of 199 placebo-controlled clinical studies involving the use of 11 different AEDs showed that patients receiving AEDs had approximately twice the risk of suicidal thinking or behavior compared to patients receiving placebo. AEDs should be administered cautiously in patients with depression or other psychiatric disorders; phentermine-topiramate should be avoided in patients with history of suicidal attempts or active suicidal ideation. The risk of suicidal thoughts and behavior should be carefully assessed against the risk of untreated illness, bearing in mind that epilepsy and many other conditions for which AEDs are prescribed are themselves associated with morbidity and mortality and an increased risk of suicidal thoughts and behavior. Patients, caregivers, and families should be alert to the emergence or worsening of signs and symptoms of depression, any unusual changes in mood or behavior, or the emergence of suicidal thoughts or behavior. If patients have symptoms of suicidal ideation or behavior, a dosage reduction or treatment discontinuation should be considered.

Pulmonary Arterial Hypertension

Major:

fenfluramine

Fenfluramine has a major potential interaction with Pulmonary Arterial Hypertension.

Serotonergic drugs with 5-HT2B receptor agonist activity, including fenfluramine, have been associated with pulmonary arterial hypertension. Exercise care when using this agent in patients with pulmonary disease. Cardiac monitoring is required before starting, during, and after treatment. Cardiac monitoring via echocardiogram can identify evidence of pulmonary arterial hypertension. If pulmonary arterial hypertension is observed on an echocardiogram, the prescriber must consider the benefits versus the risks of initiating or continuing treatment. Echocardiograms should be repeated every six months, and once 3-6 months posttreatment.

Renal Dysfunction

Moderate:

fenfluramine

Fenfluramine has a moderate potential interaction with Renal Dysfunction.

Fenfluramine has not been studied in patients with end-stage renal disease (eGFR less than 15 mL/min/1.73 m2). In patients with severe renal dysfunction (eGFR 15 to 29 mL/min/1.73 m2) the maximum daily dosage of 20 mg per day should not be exceeded (17 mg per day if concomitant stiripentol is used). No dose adjustments are required for patients with mild and moderate renal dysfunction.

Moderate:

Lipitor

The atorvastatin in Lipitor has a moderate potential interaction with Renal Dysfunction.

HMG-CoA reductase inhibitors may cause myopathy and rhabdomyolysis; acute renal failure secondary to myoglobinuria and rare fatalities have occurred due to rhabdomyolysis in patients treated with statins. The myopathy may be dose-related and is characterized by unexplained muscle weakness, pain, or tenderness accompanied by increases in creatine phosphokinase (CPK) values exceeding 10 times the upper limit of normal. Therapy with HMG-CoA reductase inhibitors should be administered cautiously in patients with preexisting myopathy, in those with predisposing factors for myopathy, or with a history of myoneural disorder, since it may delay the recognition or confound the diagnosis of a drug-induced musculoskeletal effect. Patients should be advised to report promptly any unusual muscle pain, tenderness, or weakness, particularly if accompanied by malaise or fever. Periodic CPK determinations may be considered in some patients, although the value of such monitoring is uncertain. HMG-CoA reductase inhibitor therapy should be withdrawn if markedly elevated CPK levels occur or if drug-related myopathy is diagnosed or suspected.

Moderate:

Lipitor

The atorvastatin in Lipitor has a moderate potential interaction with Renal Dysfunction.

Some HMG-CoA reductase inhibitors (e.g., fluvastatin) have not been studied in patients with severe renal dysfunction or end-stage renal disease. Some others (e.g., pitavastatin, simvastatin) require a dose reduction when used in this group of patients. Caution and close monitoring are advised when using these drugs in patients with renal dysfunction.

Underactive Thyroid

Moderate:

Lipitor

The atorvastatin in Lipitor has a moderate potential interaction with Underactive Thyroid.

HMG-CoA reductase inhibitors may cause myopathy and rhabdomyolysis; acute renal failure secondary to myoglobinuria and rare fatalities have occurred due to rhabdomyolysis in patients treated with statins. The myopathy may be dose-related and is characterized by unexplained muscle weakness, pain, or tenderness accompanied by increases in creatine phosphokinase (CPK) values exceeding 10 times the upper limit of normal. Therapy with HMG-CoA reductase inhibitors should be administered cautiously in patients with preexisting myopathy, in those with predisposing factors for myopathy, or with a history of myoneural disorder, since it may delay the recognition or confound the diagnosis of a drug-induced musculoskeletal effect. Patients should be advised to report promptly any unusual muscle pain, tenderness, or weakness, particularly if accompanied by malaise or fever. Periodic CPK determinations may be considered in some patients, although the value of such monitoring is uncertain. HMG-CoA reductase inhibitor therapy should be withdrawn if markedly elevated CPK levels occur or if drug-related myopathy is diagnosed or suspected.

Valvular Heart Disease

Major:

fenfluramine

Fenfluramine has a major potential interaction with Valvular Heart Disease.

Serotonergic drugs with 5-HT2B receptor agonist activity, including fenfluramine have been associated with valvular heart disease. Exercise care when using this agent in patients with cardiac disease. Cardiac monitoring is required prior to starting, during, and after treatment. If valvular heart disease is observed on an echocardiogram, the prescriber must consider the benefits versus the risks of initiating or continuing treatment. Echocardiograms should be repeated every six months, and once 3-6 months posttreatment.

Visual Defect/Disturbance

Moderate:

fenfluramine

Fenfluramine has a moderate potential interaction with Visual Defect/Disturbance.

Fenfluramine can cause mydriasis and can precipitate angle-closure glaucoma. Exercise care when using this agent in patients with visual disturbances. Consider discontinuing treatment in patients with acute decrease in visual acuity or ocular pain.

More resources

fenfluramine

A total of 850 drugs are known to interact with fenfluramine.

Lipitor

A total of 437 drugs are known to interact with Lipitor.

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

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