Skip to main content

Can you take Fosphenytoin with Mysoline?

1 drug interaction and 48 additional warnings found for the following 2 drugs:

Add/remove drugs

Drug interactions

Moderate drug interactions

Moderate:

primidone fosphenytoin

Applies to: Mysoline (primidone) and fosphenytoin

Using fosphenytoin together with primidone may affect your seizure control. You may need dose adjustments or special tests in order to safely take both medications together. This combination may alter fosphenytoin levels. You should notify your doctor if you have a loss of seizure control or possible symptoms such as nausea, vomiting, tremors, loss of muscle coordination, lethargy, slurred speech, visual disturbances, or changes in mental status. It is important that you tell your healthcare provider about all other medications that you are using including vitamins and herbs. Do not stop using your medications without first talking to your doctor.

Food/lifestyle interactions

Major food/lifestyle interactions

Major:

primidone Alcohol (Ethanol)

Applies to: Mysoline (primidone)

Ask your doctor before using primidone together with ethanol (alcohol), this can add to dizziness, drowsiness and other side effects of primidone. Be careful if you drive or do activities that require you to be awake and alert. Talk with your doctor before using any medications together, or drinking alcohol with primidone. It is important to tell your doctor about all other medications you use, including vitamins and herbs. Do not stop using any medications without first talking to your doctor.

Disease interactions

47 potential interactions Applies to: 24 conditions, including Depression, Vitamin D Deficiency, Hypotension, Psychosis, and Heart Disease.

Abnormal Glucose Tolerance

Moderate:

fosphenytoin

Fosphenytoin has a moderate potential interaction with Abnormal Glucose Tolerance.

Phenytoin, particularly in high dosages, may cause hyperglycemia by inhibiting insulin release. The drug may also raise serum glucose levels in diabetic patients. Therapy with phenytoin should be administered cautiously in patients with diabetes mellitus, glucose intolerance, or a predisposition to hyperglycemia. Patients with diabetes mellitus should be monitored more closely during phenytoin therapy, and their antidiabetic regimen adjusted accordingly. The same precautions should also be observed with other hydantoin anticonvulsants (i.e. ethotoin and mephenytoin) because of their structural and pharmacological similarities to phenytoin.

Acute Alcohol Intoxication

Major:

Mysoline

The primidone in Mysoline has a major potential interaction with Acute Alcohol Intoxication.

The use of barbiturates is contraindicated in patients with acute alcohol intoxication exhibiting depressed vital signs. The central nervous system depressant effects of barbiturates may be additive with those of alcohol. Severe respiratory depression and death may occur. Therapy with barbiturates should be administered cautiously in patients who might be prone to acute alcohol intake.

Adrenal Insufficiency

Moderate:

Mysoline

The primidone in Mysoline has a moderate potential interaction with Adrenal Insufficiency.

Since primidone is structurally related to the barbiturate-derivative anticonvulsants and also partially metabolized to phenobarbital during chronic administration, the usual contraindications, warnings and precautions applicable to barbiturates should be observed with primidone.

Moderate:

Mysoline

The primidone in Mysoline has a moderate potential interaction with Adrenal Insufficiency.

Barbiturates, especially phenobarbital, secobarbital and butabarbital, may diminish the systemic effects of exogenous and endogenous corticosteroids via induction of hepatic microsomal enzymes, thereby accelerating the metabolism of corticosteroids. In addition, barbiturates may interfere with pituitary corticotropin production. Therapy with barbiturates should be administered cautiously in patients with adrenal insufficiency. Patients with borderline hypoadrenalism should be monitored closely, and patients receiving steroid supplementation may require an adjustment in dosage when barbiturates are added to or withdrawn from their medication regimen.

Alcoholism

Major:

Mysoline

The primidone in Mysoline has a major potential interaction with Alcoholism.

Since primidone is structurally related to the barbiturate-derivative anticonvulsants and also partially metabolized to phenobarbital during chronic administration, the usual contraindications, warnings and precautions applicable to barbiturates should be observed with primidone.

Major:

Mysoline

The primidone in Mysoline has a major potential interaction with Alcoholism.

Barbiturates have the potential to cause dependence and abuse. Tolerance as well as physical and psychological dependence can develop, particularly after prolonged use of excessive dosages. Abrupt cessation and/or a reduction in dosage may precipitate withdrawal symptoms. In patients who have developed tolerance to a barbiturate, overdosage can still produce respiratory depression and death, and cross-tolerance usually will occur with other agents in the class. Addiction-prone individuals, such as those with a history of alcohol or substance abuse, should be under careful surveillance or medical supervision when treated with barbiturates. It may be prudent to refrain from dispensing large quantities of medication to these patients. After prolonged use or if dependency is suspected, withdrawal of barbiturates should be undertaken gradually using a dosage-tapering schedule.

Moderate:

fosphenytoin

Fosphenytoin has a moderate potential interaction with Alcoholism.

The use of acute alcoholic intake may increase phenytoin serum levels while chronic alcoholic use may decrease serum levels. Caution is recommended in alcoholic patients. The same precaution should also be observed with fosphenytoin as this agent is a prodrug of phenytoin.

Anemia, Folate Deficiency

Moderate:

fosphenytoin

Fosphenytoin has a moderate potential interaction with Anemia, Folate Deficiency.

Hydantoin anticonvulsants may interfere with folate metabolism and precipitate macrocytosis and megaloblastic anemia, which usually respond to folic acid therapy. These reactions have been fairly uncommon but may be of concern in patients with megaloblastic anemia or folate deficiency receiving hydantoin therapy.

Asphyxia

Major:

Mysoline

The primidone in Mysoline has a major potential interaction with Asphyxia.

Barbiturates may produce severe respiratory depression, apnea, laryngospasm, bronchospasm and cough, particularly during rapid intravenous administration. In usual hypnotic dosages, the degree of respiratory depression produced is similar to that which occurs during physiologic sleep, while at higher dosages, the rate, depth and volume of respiration may be markedly decreased. However, some patients may be susceptible at commonly used dosages, including the elderly, debilitated or severely ill patients, those receiving other CNS depressants, and those with limited ventilatory reserve, chronic pulmonary insufficiency or other respiratory disorders. Therapy with barbiturates should be administered cautiously in these patients. Appropriate monitoring and individualization of dosage are particularly important, and equipment for resuscitation should be immediately available if the parenteral route is used. Barbiturates, especially injectable formulations, should generally be avoided in patients with sleep apnea, hypoxia, or severe pulmonary diseases in which dyspnea or obstruction is evident.

Major:

Mysoline

The primidone in Mysoline has a major potential interaction with Asphyxia.

Since primidone is structurally related to the barbiturate-derivative anticonvulsants and also partially metabolized to phenobarbital during chronic administration, the usual contraindications, warnings and precautions applicable to barbiturates should be observed with primidone.

Bone Marrow Depression/Low Blood Counts

Major:

fosphenytoin

Fosphenytoin has a major potential interaction with Bone Marrow Depression/Low Blood Counts.

Hematologic toxicities have been associated with the use of hydantoin anticonvulsants, particularly mephenytoin. Thrombocytopenia, leukopenia, neutropenia, agranulocytosis, pancytopenia and, rarely, hemolytic anemia, aplastic anemia and pure red cell aplasia have been reported. Therapy with hydantoin anticonvulsants should be administered cautiously in patients with preexisting blood dyscrasias and/or bone marrow depression. Complete blood counts, including platelets, should be performed prior to initiating therapy and regularly for several months thereafter. For mephenytoin, the manufacturer recommends performing counts after 2 weeks on a low dosage, after another 2 weeks when full dosage is reached, then monthly for a year, and every 3 months thereafter. Marked depression of blood counts may be indication for withdrawal of hydantoin therapy.

Moderate:

Mysoline

The primidone in Mysoline has a moderate potential interaction with Bone Marrow Depression/Low Blood Counts.

Hematologic toxicity, including agranulocytosis, thrombocytopenic purpura and megaloblastic anemia, has been reported rarely during use of barbiturates. Therapy with barbiturates should be administered cautiously in patients with preexisting blood dyscrasias or bone marrow suppression. Blood counts are recommended prior to and periodically during long-term therapy, and patients should be instructed to immediately report any signs or symptoms suggestive of blood dyscrasia such as fever, sore throat, local infection, easy bruising, petechiae, bleeding, pallor, dizziness, or jaundice. Barbiturate therapy should be discontinued if blood dyscrasias occur.

Moderate:

Mysoline

The primidone in Mysoline has a moderate potential interaction with Bone Marrow Depression/Low Blood Counts.

Since primidone is structurally related to the barbiturate-derivative anticonvulsants and also partially metabolized to phenobarbital during chronic administration, the usual contraindications, warnings and precautions applicable to barbiturates should be observed with primidone.

Depression

Major:

Mysoline

The primidone in Mysoline has a major potential interaction with Depression.

Since primidone is structurally related to the barbiturate-derivative anticonvulsants and also partially metabolized to phenobarbital during chronic administration, the usual contraindications, warnings and precautions applicable to barbiturates should be observed with primidone.

Moderate:

fosphenytoin

Fosphenytoin 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.

Moderate:

Mysoline

The primidone in Mysoline 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.

Moderate:

Mysoline

The primidone in Mysoline has a moderate potential interaction with Depression.

Barbiturates depress the central nervous system and may cause or exacerbate mental depression. Therapy with barbiturates should be administered cautiously in patients with a history of depression or suicidal tendencies. It may be prudent to refrain from dispensing large quantities of medication to these patients.

Dermatitis, Drug-Induced

Major:

Mysoline

The primidone in Mysoline has a major potential interaction with Dermatitis, Drug-Induced.

Since primidone is structurally related to the barbiturate-derivative anticonvulsants and also partially metabolized to phenobarbital during chronic administration, the usual contraindications, warnings and precautions applicable to barbiturates should be observed with primidone.

Major:

Mysoline

The primidone in Mysoline has a major potential interaction with Dermatitis, Drug-Induced.

Skin eruptions may precede rare but potentially fatal barbiturate-induced reactions such as systemic lupus erythematosus and exfoliative dermatitis, the latter of which may be accompanied by hepatitis and jaundice. Therapy with barbiturates should be administered cautiously in patients with preexisting drug-induced dermatitis, since it may delay the recognition of a potential reaction to barbiturates. Barbiturate therapy should be withdrawn promptly at the first sign of a dermatologic adverse effect. However, cutaneous reactions may proceed to an irreversible stage even after cessation of medication due to the slow rate of metabolism and excretion of barbiturates. Patients should be advised to promptly report signs that may indicate impending development of barbiturate-related cutaneous lesions, including high fever, severe headache, stomatitis, conjunctivitis, rhinitis, urethritis, and balanitis. Rashes may be more likely to occur with phenobarbital and mephobarbital.

Diabetes Mellitus

Moderate:

fosphenytoin

Fosphenytoin has a moderate potential interaction with Diabetes Mellitus.

Phenytoin, particularly in high dosages, may cause hyperglycemia by inhibiting insulin release. The drug may also raise serum glucose levels in diabetic patients. Therapy with phenytoin should be administered cautiously in patients with diabetes mellitus, glucose intolerance, or a predisposition to hyperglycemia. Patients with diabetes mellitus should be monitored more closely during phenytoin therapy, and their antidiabetic regimen adjusted accordingly. The same precautions should also be observed with other hydantoin anticonvulsants (i.e. ethotoin and mephenytoin) because of their structural and pharmacological similarities to phenytoin.

Drug Dependence

Major:

Mysoline

The primidone in Mysoline has a major potential interaction with Drug Dependence.

Barbiturates have the potential to cause dependence and abuse. Tolerance as well as physical and psychological dependence can develop, particularly after prolonged use of excessive dosages. Abrupt cessation and/or a reduction in dosage may precipitate withdrawal symptoms. In patients who have developed tolerance to a barbiturate, overdosage can still produce respiratory depression and death, and cross-tolerance usually will occur with other agents in the class. Addiction-prone individuals, such as those with a history of alcohol or substance abuse, should be under careful surveillance or medical supervision when treated with barbiturates. It may be prudent to refrain from dispensing large quantities of medication to these patients. After prolonged use or if dependency is suspected, withdrawal of barbiturates should be undertaken gradually using a dosage-tapering schedule.

Major:

Mysoline

The primidone in Mysoline has a major potential interaction with Drug Dependence.

Since primidone is structurally related to the barbiturate-derivative anticonvulsants and also partially metabolized to phenobarbital during chronic administration, the usual contraindications, warnings and precautions applicable to barbiturates should be observed with primidone.

Folic Acid/Cyanocobalamin Deficiency

Moderate:

fosphenytoin

Fosphenytoin has a moderate potential interaction with Folic Acid/Cyanocobalamin Deficiency.

Hydantoin anticonvulsants may interfere with folate metabolism and precipitate macrocytosis and megaloblastic anemia, which usually respond to folic acid therapy. These reactions have been fairly uncommon but may be of concern in patients with megaloblastic anemia or folate deficiency receiving hydantoin therapy.

Heart Disease

Major:

fosphenytoin

Fosphenytoin has a major potential interaction with Heart Disease.

The intravenous administration of phenytoin or its prodrug, fosphenytoin, is contraindicated in patients with sinus bradycardia, sino-atrial block, second and third degree AV block, and patients with Adam-Stokes syndrome. Severe cardiotoxic reactions related to depression of atrial and ventricular conduction and ventricular fibrillation have been reported with parenteral phenytoin, primarily in elderly or gravely ill patients. Hypotension and cardiovascular collapse have also been reported, usually when the drug was administered too rapidly. Therapy with intravenous phenytoin or fosphenytoin should be administered cautiously in patients with hypotension or severe myocardial insufficiency, particularly if they are elderly or seriously ill. The rate of injection should not exceed manufacturer recommendations and should be adjusted based on the patient's cardiovascular status. The rate of IV administration for SESQUIENT should not exceed 0.4 mg PE/kg/min in pediatric patients as safety at a faster rate has not been established.

Hyperkinetic Syndrome of Childhood

Moderate:

Mysoline

The primidone in Mysoline has a moderate potential interaction with Hyperkinetic Syndrome of Childhood.

Paradoxical reactions characterized by excitability and restlessness may occur in pediatric patients with hyperactive aggressive disorders. Such patients should be monitored for signs of paradoxical stimulation during therapy with barbiturates.

Moderate:

Mysoline

The primidone in Mysoline has a moderate potential interaction with Hyperkinetic Syndrome of Childhood.

Since primidone is structurally related to the barbiturate-derivative anticonvulsants and also partially metabolized to phenobarbital during chronic administration, the usual contraindications, warnings and precautions applicable to barbiturates should be observed with primidone.

Hypotension

Major:

fosphenytoin

Fosphenytoin has a major potential interaction with Hypotension.

The intravenous administration of phenytoin or its prodrug, fosphenytoin, is contraindicated in patients with sinus bradycardia, sino-atrial block, second and third degree AV block, and patients with Adam-Stokes syndrome. Severe cardiotoxic reactions related to depression of atrial and ventricular conduction and ventricular fibrillation have been reported with parenteral phenytoin, primarily in elderly or gravely ill patients. Hypotension and cardiovascular collapse have also been reported, usually when the drug was administered too rapidly. Therapy with intravenous phenytoin or fosphenytoin should be administered cautiously in patients with hypotension or severe myocardial insufficiency, particularly if they are elderly or seriously ill. The rate of injection should not exceed manufacturer recommendations and should be adjusted based on the patient's cardiovascular status. The rate of IV administration for SESQUIENT should not exceed 0.4 mg PE/kg/min in pediatric patients as safety at a faster rate has not been established.

Liver Disease

Major:

fosphenytoin

Fosphenytoin has a major potential interaction with Liver Disease.

Hydantoin anticonvulsants are primarily metabolized by the liver. Both metabolic activity and plasma protein binding may be significantly altered in patients with liver disease, resulting in elevated drug levels (total and unbound fraction) and increased risk of toxicity. Therapy with hydantoin anticonvulsants should be administered cautiously in patients with impaired hepatic function. Reduced dosages and slower titration may be necessary. In addition, periodic monitoring of liver function is recommended, since the use of anticonvulsants, including hydantoins, has been associated with hepatotoxicity related to drug hypersensitivity. Hepatic failure and death have occurred. Hydantoin therapy should be discontinued and not readministered if evidence of liver damage is observed and felt to be drug-related.

Major:

Mysoline

The primidone in Mysoline has a major potential interaction with Liver Disease.

During chronic administration, primidone is slowly metabolized by the liver and excreted in the urine as phenylethylmalonamide (PEMA), phenobarbital and p-hydroxyphenobarbital, the latter two of which are pharmacologically active. The plasma clearance of primidone and its metabolites may be decreased and the half-lives prolonged in patients with impaired hepatic and/or renal function. Therapy with primidone should be administered cautiously and initiated at reduced dosages in patients with liver and/or renal disease.

Panhypopituitarism

Moderate:

Mysoline

The primidone in Mysoline has a moderate potential interaction with Panhypopituitarism.

Barbiturates, especially phenobarbital, secobarbital and butabarbital, may diminish the systemic effects of exogenous and endogenous corticosteroids via induction of hepatic microsomal enzymes, thereby accelerating the metabolism of corticosteroids. In addition, barbiturates may interfere with pituitary corticotropin production. Therapy with barbiturates should be administered cautiously in patients with adrenal insufficiency. Patients with borderline hypoadrenalism should be monitored closely, and patients receiving steroid supplementation may require an adjustment in dosage when barbiturates are added to or withdrawn from their medication regimen.

Moderate:

Mysoline

The primidone in Mysoline has a moderate potential interaction with Panhypopituitarism.

Since primidone is structurally related to the barbiturate-derivative anticonvulsants and also partially metabolized to phenobarbital during chronic administration, the usual contraindications, warnings and precautions applicable to barbiturates should be observed with primidone.

Porphyria

Major:

fosphenytoin

Fosphenytoin has a major potential interaction with Porphyria.

The use of phenytoin has rarely been associated with exacerbation of porphyria. Therapy with phenytoin should be administered cautiously in patients with porphyria. The same precaution should also be observed with other hydantoin anticonvulsants (i.e. ethotoin and mephenytoin) because of their structural and pharmacological similarities to phenytoin.

Major:

Mysoline

The primidone in Mysoline has a major potential interaction with Porphyria.

The use of barbiturates is contraindicated in patients with a history of porphyria. Barbiturates may exacerbate acute intermittent porphyria or porphyria variegata by inducing the enzymes responsible for porphyrin synthesis.

Major:

Mysoline

The primidone in Mysoline has a major potential interaction with Porphyria.

Since primidone is structurally related to the barbiturate-derivative anticonvulsants and also partially metabolized to phenobarbital during chronic administration, the usual contraindications, warnings and precautions applicable to barbiturates should be observed with primidone.

Psychosis

Moderate:

fosphenytoin

Fosphenytoin 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.

Moderate:

Mysoline

The primidone in Mysoline 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 Impairment

Major:

Mysoline

The primidone in Mysoline has a major potential interaction with Pulmonary Impairment.

Since primidone is structurally related to the barbiturate-derivative anticonvulsants and also partially metabolized to phenobarbital during chronic administration, the usual contraindications, warnings and precautions applicable to barbiturates should be observed with primidone.

Major:

Mysoline

The primidone in Mysoline has a major potential interaction with Pulmonary Impairment.

Barbiturates may produce severe respiratory depression, apnea, laryngospasm, bronchospasm and cough, particularly during rapid intravenous administration. In usual hypnotic dosages, the degree of respiratory depression produced is similar to that which occurs during physiologic sleep, while at higher dosages, the rate, depth and volume of respiration may be markedly decreased. However, some patients may be susceptible at commonly used dosages, including the elderly, debilitated or severely ill patients, those receiving other CNS depressants, and those with limited ventilatory reserve, chronic pulmonary insufficiency or other respiratory disorders. Therapy with barbiturates should be administered cautiously in these patients. Appropriate monitoring and individualization of dosage are particularly important, and equipment for resuscitation should be immediately available if the parenteral route is used. Barbiturates, especially injectable formulations, should generally be avoided in patients with sleep apnea, hypoxia, or severe pulmonary diseases in which dyspnea or obstruction is evident.

Renal Dysfunction

Major:

fosphenytoin

Fosphenytoin has a major potential interaction with Renal Dysfunction.

The plasma protein binding of phenytoin may be significantly decreased in patients with renal impairment, resulting in elevated free drug concentrations and increased risk of toxicity. This effect is proportional to the degree of renal impairment and stems from quantitative differences in serum albumin as well as qualitative differences in the ability to bind phenytoin. Therapy with phenytoin should be administered cautiously in patients with impaired renal function. Both the therapeutic and toxic plasma total phenytoin levels may be lower than normal in these patients and should be considered in dosing. Alternatively, the monitoring of unbound phenytoin concentrations may be appropriate.

Major:

Mysoline

The primidone in Mysoline has a major potential interaction with Renal Dysfunction.

During chronic administration, primidone is slowly metabolized by the liver and excreted in the urine as phenylethylmalonamide (PEMA), phenobarbital and p-hydroxyphenobarbital, the latter two of which are pharmacologically active. The plasma clearance of primidone and its metabolites may be decreased and the half-lives prolonged in patients with impaired hepatic and/or renal function. Therapy with primidone should be administered cautiously and initiated at reduced dosages in patients with liver and/or renal disease.

Moderate:

fosphenytoin

Fosphenytoin has a moderate potential interaction with Renal Dysfunction.

Fosphenytoin injection (Cerebyx, Sesquient) provides a phosphate load of 0.0037 mmol per mg of phenytoin sodium equivalent activity, which should be considered in patients who require phosphate restriction, such as those with severe renal impairment. A new formulation of fosphenytoin (Sesquient) contains an excipient betadex sulfobutyl ether sodium that may accumulate as sulfobutylether beta-cyclodextrin sodium salt in patients with moderate to severe renal impairment. Serum creatinine levels should be closely monitored in patients with severe renal impairment (eGFR 15 to less than 30 mL/min/1.73 m2) and a switch to oral phenytoin should be considered if serum creatinine levels begin to rise.

Respiratory Arrest

Major:

Mysoline

The primidone in Mysoline has a major potential interaction with Respiratory Arrest.

Barbiturates may produce severe respiratory depression, apnea, laryngospasm, bronchospasm and cough, particularly during rapid intravenous administration. In usual hypnotic dosages, the degree of respiratory depression produced is similar to that which occurs during physiologic sleep, while at higher dosages, the rate, depth and volume of respiration may be markedly decreased. However, some patients may be susceptible at commonly used dosages, including the elderly, debilitated or severely ill patients, those receiving other CNS depressants, and those with limited ventilatory reserve, chronic pulmonary insufficiency or other respiratory disorders. Therapy with barbiturates should be administered cautiously in these patients. Appropriate monitoring and individualization of dosage are particularly important, and equipment for resuscitation should be immediately available if the parenteral route is used. Barbiturates, especially injectable formulations, should generally be avoided in patients with sleep apnea, hypoxia, or severe pulmonary diseases in which dyspnea or obstruction is evident.

Major:

Mysoline

The primidone in Mysoline has a major potential interaction with Respiratory Arrest.

Since primidone is structurally related to the barbiturate-derivative anticonvulsants and also partially metabolized to phenobarbital during chronic administration, the usual contraindications, warnings and precautions applicable to barbiturates should be observed with primidone.

Thyroid Disease

Moderate:

fosphenytoin

Fosphenytoin has a moderate potential interaction with Thyroid Disease.

Phenytoin may decrease serum PBI (protein-bound iodine) levels without associated thyroid disturbance. Free thyroxine concentrations may also be decreased, while resin or red cell T3 uptake values may be increased. Clinicians should be cognizant of these effects when prescribing or administering phenytoin therapy to patients with thyroid disorders.

Vitamin D Deficiency

Moderate:

fosphenytoin

Fosphenytoin has a moderate potential interaction with Vitamin D Deficiency.

Phenytoin may interfere with vitamin D metabolism. Hypocalcemia and osteomalacia have been reported. Therapy with phenytoin should be administered cautiously in patients with preexisting vitamin D deficiency. The same precaution should also be observed with other hydantoin anticonvulsants (i.e. ethotoin and mephenytoin) because of their structural and pharmacological similarities to phenytoin.

Moderate:

Mysoline

The primidone in Mysoline has a moderate potential interaction with Vitamin D Deficiency.

Rickets and osteomalacia have rarely been reported following prolonged use of barbiturates, possibly due to increased metabolism of vitamin D as a result of enzyme induction by barbiturates. Long-term therapy with barbiturates should be administered cautiously in patients with vitamin D deficiency.

Moderate:

Mysoline

The primidone in Mysoline has a moderate potential interaction with Vitamin D Deficiency.

Since primidone is structurally related to the barbiturate-derivative anticonvulsants and also partially metabolized to phenobarbital during chronic administration, the usual contraindications, warnings and precautions applicable to barbiturates should be observed with primidone.

More resources

fosphenytoin

A total of 812 drugs are known to interact with fosphenytoin.

Mysoline

A total of 730 drugs are known to interact with Mysoline.

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.