Phenytoin – What it is for, How to use it and Side Effects
Phenytoin – How to Use: Oral as a chewable, extended-release tablet or suspension (liquid). Taken one to four times a day. The prescribed dose should be adjusted every week until the number of seizures is reduced to zero in order to avoid side effects. It can be presented as acid or sodium salt. The maximum effect takes 1.5 to 6 hours. It should not be administered intramuscularly, as erratic absorption increases side effects and decreases therapeutic efficacy.
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Intravenously, the initial dose is 15 to 20mg/Kg (half in children over 1 and under 12 years old), with a maximum dose of 30mg/Kg. The maintenance dose is 4 to 10mg/kg, given 12 hours after the initial dose. Other medications should be preferred. It can be used in pregnant women as seizures are worse for mother and baby than adverse effects.
Phenytoin side effects:
- Insomnia: Difficulty sleeping or staying asleep
- Slow or confused thinking and speaking
- Nausea, vomiting or constipation
- Swelling in the face and lips
- Headache
- Nystagmus: Erratic eye muscle movements
- Hirsutism: increased amount of hair
- Ataxia: incoordination of movements
- Anemia
- Pain in the penis
- It interferes with the production pathway of 25-Hydroxyvitamin D (Vitamin D) by the liver.
- Allergic reactions are rare. It can also rarely cause bone softening, lymphatic and cardiovascular problems.
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These problems are more common in elderly and debilitated patients.