Introduction
Diphedan is a prescription medicine used to treat and prevent epilepsy (seizures). It controls seizures by decreasing the abnormal and excessive activity of the nerve cells in the brain. It is given when this medicine cannot be given orally, like in hospitalised patients.
Diphedan is given under the supervision of a healthcare professional and should not be self administered. It is advisable to take it at the same time each day as this helps to maintain constant level of medicine in the body. If you have missed a dose, take it as soon as you remember it. You should finish the full course of treatment even if you feel better as stopping the medication without talking to your doctor may cause non-stop seizures (called status epilepticus), which can be life threatening.
The most common side effects of this medicine include skin rashes, headache, feeling or being sick, difficulty sleeping, dizziness and feeling sleepy or drowsy. Additionally, you may notice some injection site reactions like redness or swelling. Most side effects wear off, but if they bother you or do not go away, tell your doctor. There may be ways of preventing or reducing these effects.
Before taking this medicine, tell your doctor if you have kidney or liver problems, meningitis or depression or suicidal thoughts. Also let your healthcare team know about all other medications you are using as some may affect, or be affected by, this medicine, including contraceptive pills. If you are pregnant or breastfeeding, Diphedan can be taken if it is clearly needed but the dose may be adjusted. You should avoid driving or riding a bicycle if this medicine makes you drowsy or dizzy. You may need frequent blood tests to check how you are responding to this medicine.
Side effects of Diphedan
Common
- Rash
- Headache
- Dizziness
- Vomiting
- Nausea
- Slurred speech
- Vertigo
- Confusion
- Nervousness
- Constipation
- Tremor
- Altered walking
How to use Diphedan
Your doctor or nurse will give you this medicine. Kindly do not self administer.
How Diphedan works
Diphedan is an antiepileptic medication. It controls seizures or fits by decreasing the abnormal and excessive activity of the nerve cells in the brain.
Indication
Epilepsy, Tonic-clonic status epilepticus
Administration
IV Preparation
Load IV in 250 mL NS; monitor BP
IV/IM Administration
Administer slowly; no more than 50 mg/min in adults and no more than 1-3 mg/kg/min in pediatric patients
Adult Dose
Status epilepticus
Load 10-15 mg/kg or 15-20 mg/kg at 25-50 mg/min, THEN
Maintenance: 100 mg IV q6-8hr PRN
Administer IV slowly; not to exceed 50 mg/min
Child Dose
Status Epilepticus
15-20 mg/kg IV in single or divided dose; if necessary may administer additional dose of 5-10 mg/kg 10 min after loading dose
Maintenance: 4-8 mg/kg/day IV divided twice daily
Contraindication
Pregnancy. IV admin in sinus bradycardia, heart block, or Stokes-Adams syndrome.
Mode of Action
Phenytoin acts as an anticonvulsant by increasing efflux or decreasing influx of sodium ions across cell membranes in the motor cortex during generation of nerve impulses; thus stabilising neuronal membranes and decreasing seizure activity. It acts as an antiarrhythmic by extending the effective refractory period and suppressing ventricular pacemaker automaticity, shortening action potential in the heart.
Precaution
Cardiovascular disease, e.g. sinus bradycardia, heart blocks; DM; hepatic impairment; hypoalbuminemia; porphyria; seizures (may increase frequency of petit mal seizures); debilitated patients; elderly. Caution in IV admin in hypotension, heart failure or MI, monitor BP and ECG during therapy. IV must be given slowly (too rapid admin may cause hypotension, CNS depression, cardiac arrhythmias and impaired heart conduction). Extravasation and intra-arterial admin must be avoided. Do not discontinue abruptly (may increase seizure frequency), unless safety concerns require a more rapid withdrawal. May impair ability to drive or operate machinery.
Lactation: Excreted in breast milk; not recommended
Side Effect
Hypersensitivity, lack of appetite, headache, dizziness, tremor, transient nervousness, insomnia, GI disturbances (e.g. nausea, vomiting, constipation), tenderness and hyperplasia of the gums, acne, hirsutism, coarsening of the facial features, rashes, osteomalacia. Phenytoin toxicity as manifested as a syndrome of cerebellar, vestibular, ocular effects, notably nystagmus, diplopia, slurred speech, and ataxia; also with mental confusion, dyskinesias, exacerbations of seizure frequency, hyperglycaemia. Solutions for inj may cause local irritation or phlebitis. Prolonged use may produce subtle effects on mental function and cognition, especially in children.
Potentially Fatal: Toxic epidermal necrolysis, Stevens-Johnson syndrome.
Interaction
Effects with other sedative drugs or ethanol may be potentiated. Enhances toxic effects of paracetamol, lithium. Increased risk of osteomalacia with acetazolamide. Decreased serum levels/effects with acyclovir, antineoplastics, benzodiazeines, ciprofloxacin, CYP2C9 inducers (e.g. carbamazepine), CYP2C19 inducers (e.g. rifampin), folic acid, vigabatrin.
Increased serum concentrations with allopurinol, capecitabine, cimetidine, CYP2C9 inhibitors (e.g. fluconazole), CYP2C19 inhibitors (e.g. delavirdine), disulfiram, methylphenidate, metronidazole, omeprazole, SSRI, trazodone, trimethoprim. Increases metabolism of antiarrhythmics, anticonvulsants, antipsychotics, beta-blockers, calcium channel blockers, chloramphenicol, corticosteroids, doxycycline, oestrogens, HMG-CoA reductase inhibitors, methadone, theophylline, TCAs. Decreases levels/effects of clozapine, ciclosporin, tacrolimus, CYP2B6 substrates (e.g. bupropion, selegiline), CYP2C8 substrates (e.g. amiodarone), CYP2C9 substrates (e.g. celecoxib), CYP2C19 substrates (e.g. citalopram), CYP3A4 substrates (e.g. benzodiazepines), digoxin, itraconazole, levodopa, neuromuscular-blocking agents, thyroid hormones, topiramate.
Increases levels/effect of dopamine, ticlopidine. Valproic acid may displace phenytoin from binding sites; and affect phenytoin serum concentrations. Transiently increases the hypothrombinaemia response to warfarin initially, followed by an inhibition of the response.
Potentially Fatal: Enhances the hypotensive properties of dopamine and the cardiac depressant properties of lidocaine.