Phenytoin is used to control certain type of seizures, and to treat and prevent seizures that may begin during or after surgery to the brain or nervous system. Phenytoin is in a class of medications called
anticonvulsants
.
What is the chemical structure of phenytoin?
Phenytoin (PHT;
5,5-
diphenylhydantoin) is a weak acid with pKa of 8.3 (1). The compound is a crystalline substance with a molecular weight of 252.3 and a melting point of 295-298 C.
What is phenytoin made of?
Each Dilantin— 100 mg Extended Oral Capsule—contains
100 mg phenytoin sodium
. Also contains lactose monohydrate, NF; confectioner’s sugar, NF; talc, USP; and magnesium stearate, NF. The capsule body contains titanium dioxide, USP and gelatin, NF. The capsule cap contains FD&C red No.
What is phenytoin mixed with?
For administration by intravenous infusion phenytoin injection should be diluted in 50 – 100 ml
of normal saline
, and the final concentration of phenytoin in the solution should not exceed 10 mg/ml, the infusion mixture should not be refrigerated.
What is mechanism of phenytoin?
Mechanism of action
Phenytoin is believed
to protect against seizures by causing voltage-dependent block of voltage gated sodium channels
. This blocks sustained high frequency repetitive firing of action potentials.
What is another name for phenytoin?
Phenytoin (FEN-ih-toe-in) is the generic name (non–brand name) of a widely used seizure medicine. Common brand names for this type of medicine include
Dilantin, Phenytek
, and Epanutin (in the UK), but it is also sold using the name phenytoin or phenytoin sodium.
What is normal phenytoin level?
Obtain a serum phenytoin level. The therapeutic range is
10-20 mcg/mL
.
Who should not take phenytoin?
You should not use phenytoin if you are allergic to it, or if you have ever had:
Tell your doctor
if you have ever had: Some people have thoughts about suicide while taking phenytoin. Your doctor will need to check your progress at regular visits.
Can phenytoin be harmful?
The neurotoxic effects are concentration dependent and can range from mild nystagmus to ataxia, slurred speech, vomiting, lethargy and eventually coma and death. Paradoxically, at very high concentrations, phenytoin can
lead to seizures
. Symptoms correlate well with the unbound plasma phenytoin concentration.
Does phenytoin cause memory loss?
All drugs that depress signaling in the CNS can cause memory loss
. Alternatives: Many patients with seizures do well on phenytoin (Dilantin), which has little if any impact on memory.
What is the side effect of phenytoin?
Side Effects
Headache, nausea, vomiting, constipation, dizziness, feeling of spinning, drowsiness, trouble sleeping
, or nervousness may occur. If any of these effects persist or worsen, tell your doctor or pharmacist promptly. Phenytoin may cause swelling and bleeding of the gums.
When do you give phenytoin?
Phenytoin typical doses are 3–5mg/kg/day. The
first dose should be given 12–24 hours after the loading dose
. Oral or nasogastric administration should be used, whenever possible. Only use intravenous administration when these options are not feasible and where cardiac monitoring is available.
When should phenytoin levels be taken?
A level can be taken
2-4 hours following an IV loading or top-up dose
(12-24 hours for oral doses) and levels should then be monitored every 24 hours until control is achieved and concentration has stabilised.
What does phenytoin do to the brain?
Phenytoin works
by slowing down impulses in the brain that cause seizures
. Phenytoin is used to control seizures. It does not treat all types of seizures, and your doctor will determine if it is the right medicine for you.
Does phenytoin affect immune system?
Results of clinical studies indicate that phenytoin, carbamazepine, and valproate, show immunosuppressive activity,
inhibit protein synthesis in lymphocytes
, decrease CD4+/CD8+ ratio, decrease IgA, and induce changes in IgG and IgM plasma levels.
What is the indication of phenytoin?
Phenytoin is indicated to treat
grand mal seizures, complex partial seizures
, and to prevent and treat seizures during or following neurosurgery.
