By Michelle Welborn, PharmD
Medically Reviewed by Nicole Cheung, PharmD, BCPS
Last Update: August 13, 2024
Valparin (Valproic acid) is a medication applied for epilepsy treatment in adults and children. This medication is determined as one of the most vital for epilepsy sufferers.
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Table of Contents
- Indications
- Dosage and Instruction for Use
- Overdose
- Contraindications
- Side Effects
- Drug Interactions
- Special Recommendations
- Storage
Product Info
Indications
In adults, as a monotherapy or in combination with other antiepileptic drugs:
- treatment of generalized epileptic seizures (clonic, tonic, tonic-clonic, absences, myoclonic, atonic); Lennox-Gastaut syndrome;
- treatment of partial, epileptic seizures (partial seizures with or without secondary generalization);
- treatment and prevention of the manic-depressive disorder.
In children as monotherapy or in combination with other antiepileptic drugs:
- treatment of generalized epileptic seizures (clonic, tonic, tonic-clonic, absences, myoclonic, atonic); Lennox-Gastaut syndrome;
- treatment of partial epileptic seizures (partial seizures with or without secondary generalization).
Dosage and Instruction for Use
The dosage is chosen individually depending on patient’s age and body weight.
The initial daily dosage for adults and children weighing more than 25 kg is usually 10-15 mg/kg. Then the dose is gradually increased by 5-10 mg/kg per week until the optimal effect is achieved. The average daily dose for 30 mg/kg body weight can be increased to 60 mg/kg when the blood plasma is examined constantly.
The dose is calculated in mg (1 ml of the drug contains 40 mg of Valproic Acid). It is taken during meals.
The daily dose is recommended to be divided into 2-3 doses.
Overdose
Symptoms: nausea, vomiting, dizziness, diarrhea, impaired breathing function, muscle hypotension, hyporeflexia, miosis, coma with muscle hypotension, hyporeflexia, miosis, respiratory depression, metabolic acidosis; cases of intracranial hypertension associated with cerebral edema.
Treatment: in the hospital – gastric lavage, if after taking the drug has passed no more than 10-12 hours; monitoring the state of the cardiovascular and respiratory systems and maintaining an effective diuresis. In very severe cases, dialysis is performed. As a rule, the prognosis is favorable, however, several cases of lethal outcome have been described.
Contraindications
- hypersensitivity to valproic acid or other components of the drug;
- acute hepatitis;
- chronic hepatitis;
- liver disease in history, porphyria;
- combination with mefloquine;
- combination with St. John’s wort;
- simultaneous use in combination with lamotrigine.
Taken with caution:
- bone marrow hemopoiesis (leukopenia, thrombocytopenia, anemia);
- organic brain diseases;
- liver and pancreatic disease in history;
- hypoproteinemia;
- mental retardation in children;
- congenital fermentopathy;
- renal failure.
Side Effects
- central nervous system: ataxia; cases of cognitive impairment with a progressive development of a complete picture of dementia syndrome (reversible within a few weeks or months after discontinuation of the drug); convulsions; lethargy; a transient coma (encephalopathy); reversible parkinsonism; headache; dizziness; slight postural tremor and drowsiness; changes in behavior; mood swings or mental state (depression, fatigue, hallucinations, aggressiveness, hyperactive state, psychoses, unusual arousal, motor anxiety or irritability), dysarthria.
- digestive system: gastrointestinal disorders (nausea, vomiting, gastralgia, decreased appetite or increased appetite, diarrhea), which usually occur for several days without drug withdrawal; abnormal liver function; pancreatitis, up to severe lesions with a fatal outcome (in the first 6 months of treatment, more often at 2-12 weeks).
- organs of hematopoiesis and system of hemostasis: anemia, leukopenia or pancreatinia; thrombocytopenia, decreased fibrinogen and platelet aggregation, leading to the development of hypocoagulation (accompanied by prolonged bleeding time, petechial hemorrhages, bruising, bleeding, etc.).
- urinary system: enuresis; cases of reversible Fanconi syndrome (unclear genesis).
- endocrine system: dysmenorrhea, secondary amenorrhea, enlargement of the mammary glands, galactorrhea.
- allergic reactions: skin rash, hives, vasculitis; angioedema, photosensitization, cases of toxic epidermal necrolysis, Stevens-Johnson syndrome, multiform erythema.
- laboratory indicators: isolated and moderate hyperammonemia without changes in liver function tests, especially with polytherapy (drug cancellation is not required); Possible hyperammonemia associated with neurologic symptoms (further examination is required); may increase the activity of “liver” transaminases; decreased fibrinogen content or increased bleeding time, usually without clinical symptoms and especially at high doses; hyponatremia.
- other: teratogenic risk; diplopia, nystagmus, alopecia; reversible or irreversible hearing loss; peripheral edema; increase in body weight; violation of the menstrual cycle, amenorrhea, impairment of the immune system.
Drug Interactions
Contraindicated Combinations
- Mefloquine: risk of epileptic seizures in patients with epilepsy due to increased metabolism of valproic acid and a convulsant effect of mefloquine.
- Hypericum tincture: the risk of a decrease in the concentration of valproic acid in blood plasma.
Unrecommended Combinations
Lamotrigine: an increased risk of severe skin reactions until the development of toxic epidermal necrolysis. In addition, an increase in the concentration of lamotrigine in plasma. If a combination is necessary, careful clinical and laboratory testing is required.
Combinations Requiring Precautions
- Carbamazepine: an increase in the concentration of the active metabolite of carbamazepine in plasma with signs of overdose. In addition, a decrease in the concentration of valproic acid in plasma, associated with increased metabolism of valproic acid in the liver under the influence of carbamazepine. Recommended: clinical observation, determination of plasma concentrations of drugs and, possibly, correction of their dose, especially at the beginning of treatment.
- Carbapenems, monobactams: meropenem, panipenem, aztreonam and imipenem: an increased risk of seizures due to a decrease in the concentration of valproic acid in the blood plasma. It is recommended: clinical observation, determination of plasma drug concentrations, valproic acid dose adjustment may be required during treatment with an antibacterial agent and after its withdrawal.
- Felbamate: an increase in the concentration of valproic acid in the blood plasma with a risk of overdose. Recommended: clinical and laboratory monitoring and, possibly, a review of the dose of valproic acid during treatment with felbamate and after its cancellation).
- Phenobarbital, primidon: increasing the concentration of phenobarbital and primidone in the plasma with signs of their overdose, usually in children. In addition, a decrease in the concentration of valproic acid in plasma, due to the increase in its hepatic metabolism under the influence of phenobarbital or primidone. It is recommended: clinical monitoring during the first 15 days of combined treatment with immediate reduction of the dose of phenobarbital or primidone when the first symptoms of sedation appear, the determination of concentrations of both anticonvulsants in the blood.
- Phenytoin: a change in the concentration of phenytoin in the plasma, a danger of a decrease in the concentration of valproic acid, associated with an increase in the metabolism of valproic acid in the liver under the influence of phenytoin. It is recommended: clinical monitoring with determination of concentrations of both antiepileptic drugs in plasma and, if necessary, correction of their doses.
- Topiramate: a risk of developing hyperammonemia or encephalopathy. Recommended: clinical and laboratory monitoring during the first month of treatment and in case of symptoms of ammoniasis.
- Neuroleptics, monoamine oxidase inhibitors (MAO), antidepressants, benzodiazepines: Valproic acid potentiates the effect of psychotropic drugs, such as neuroleptics, MAO inhibitors, antidepressants, benzodiazepines. Recommended: clinical monitoring and, if necessary, dose adjustment.
- Cimetidine and erythromycin: the concentration of valproic acid in the blood plasma increases.
- Zidovudine: valproic acid may increase the concentration of zidovudine in the plasma, which leads to an increase in zidovudine toxicity.
- Combinations that Should be Taken into Account
- Nimodipine: strengthening the hypotensive effect of nimodipine due to a decrease in its metabolism under the influence of valproic acid and an increase in the concentration in the blood plasma.
- Acetylsalicylic acid: an increase in the effects of valproic acid due to an increase in its concentration in the blood plasma.
Other Forms of Interaction
Valproic acid does not possess an enzyme-inducing effect and therefore does not affect the hormonal contraceptives containing combinations of estrogen and progesterone.
Special Recommendations
In animal studies, a teratogenic effect is observed.
According to available clinical data, valproic acid mainly causes disruption of the development of the neural tube in humans: myelomeningocele, spina bifida (1-2%). Cases of facial dysmorphia and developmental limb abnormalities (especially limb shortening), as well as developmental defects of the cardiovascular system are described.
The risk of malformations is higher with combined antiepileptic therapy than with monotherapy with valproic acid.
During pregnancy, the drug use is only possible if the intended benefit to the mother exceeds the potential risk to the fetus. During pregnancy, antiepileptic treatment with valproic acid should not be withdrawn if it is effective. In such cases, monotherapy is recommended; The minimum daily dose should be divided into 2 doses.
In addition to anti-epileptic therapy, folic acid preparations (at a dose of 5 mg/day) can be added, they minimize the risk of developing neural tube defects.
Valproic acid can cause hemorrhagic syndrome in newborns, which, apparently, is associated with hypofibrinogenemia. There have been cases of development of fetal affinity with lethal outcome. Perhaps it takes place due to a decrease in a number of clotting factors.
Valproic acid is penetrated breast milk in concentrations from 1% to 10%. It is recommended to stop breastfeeding while taking the drug.
Storage
Store at a temperature of no higher than 30 °C in a dark place. Keep out of the reach of children. The shelf life is 2 years. Do not use after the time specified on the package.
About the Author
Michelle Welborn, who holds a Doctor of Pharmacy degree from Campbell University, is the President of MWelborn Group, LLC, a consulting firm specializing in regulatory guidance for companies seeking FDA Orphan Designation and marketing approval. With 15 years of experience in pharmaceuticals, she has held key roles in Medical and Regulatory Affairs at Astra-Merck and Sanofi-Aventis, and served as a Clinical Pharmacy Manager for an HMO. Her deep understanding of childhood epilepsy, rare diseases, and drug development is driven by her daughter Lilly’s battle with Dravet syndrome. Michelle is a passionate advocate, representing children with rare diseases at international conferences and serving on advisory boards, including the Charlie Foundation and Lennox-Gastaut Syndrome Foundation.
Disclaimer: The information presented is for informational purposes only and should not be considered as medical advice. It is essential to consult a qualified healthcare provider before making any healthcare or medication decisions. This content is not a substitute for professional medical advice, diagnosis, or treatment.