Hydantoins and Magnesium Functions

Questions and Answers

What is the action of magnesium?

Magnesium decreases the acetylcholine in the motor nerve terminals and acts on the myocardium by slowing the rate at the SA node impulse in the formation and prolonging the conduction time.

Why is magnesium necessary for cells?

Magnesium is necessary for the movement of calcium, sodium, and potassium out of the cell as well as stabilizing the excitable membranes.

How is magnesium used as a seizure prophylaxis for Eclampsia?

Magnesium sulfate is used as a seizure prophylaxis for women with mild or severe eclampsia with IV infusion or IM injections.

What are the assessments for patients on magnesium?

Vital signs, oxygen concentration, deep tendon reflexes, level of consciousness, fetal heart rate, and maternal uterine activity. Signup and view all the answers

What are the three major classes of anticonvulsants?

Hydantoins, Iminostilbenes, and Succinimides. Signup and view all the answers

What is the prototype drug for the Hydantoins?

Phenytoin Signup and view all the answers

What are the drugs included in the hydantoin class of drugs?

Phenytoin, Ethotoin, and Fosphenytoin. Signup and view all the answers

What is the Hydantoin's mode of action?

The hydantoins inhibit and stabilize the electrical discharges in the motor cortex of the brain. Signup and view all the answers

How is Phenytoin used in surgery?

Phenytoin is used in neurosurgery to treat seizures. Signup and view all the answers

How is phenytoin used for seizures?

Phenytoin is used for status epilepticus after benzodiazepines and controls partial and generalized seizures. Signup and view all the answers

What are the pharmacokinetics of Hydantoins?

Slow onset of action; peak in 4 to 12 hours for extended release and 1.5-3 hours in rapid release. Signup and view all the answers

What are the pharmacotherapeutics of hydantoins?

Assess for phenytoin hypersensitivity, phenytoin-induced hepatitis, rash, arthralgia, and lymphadenopathy. Signup and view all the answers

What are the contraindications of hydantoins?

Sinus bradycardia, sinoatrial block, Stokes-Adams syndrome, and second and third-degree atrioventricular block. Signup and view all the answers

When should hydantoins be used with caution?

In patients with renal and hepatic insufficiency. Signup and view all the answers

What is the contraindication of Ethotoin?

Hepatic or hematologic disorders. Signup and view all the answers

How can pregnant women decrease fetal risk?

By taking 400 international units of Folic acid during pregnancy. Signup and view all the answers

What are the adverse drug effects of hydantoins?

Agitation, ataxia, confusion, dizziness, drowsiness, headache, nystagmus, and other side effects. Signup and view all the answers

What interactions increase the plasma level of hydantoins?

Allopurinol, cimetidine, diazepam, disulfiram, alcohol, and others. Signup and view all the answers

What is Diastat?

A rectal form of Diazepam for status epilepticus. Signup and view all the answers

What drugs decrease the plasma level of hydantoins?

Barbiturates, carbamazepine, chronic alcohol use, and others. Signup and view all the answers

What drugs do hydantoins decrease the effect of?

Corticosteroids, digoxin, doxycycline, oral contraceptives, and others. Signup and view all the answers

What should be assessed in patients for hypersensitivity syndrome?

Fever, rash, lymphadenopathy, blood count, UA, liver function. Signup and view all the answers

What is the therapeutic range of hydantoin?

10-20 mcg/ml Signup and view all the answers

Study Notes

Magnesium's Role and Importance

Magnesium decreases acetylcholine at motor nerve terminals, slow SA node impulse, and prolongs conduction time in the myocardium.
Vital for movement of calcium, sodium, and potassium out of cells and stabilizes excitable membranes.

Magnesium Sulfate in Eclampsia Management

Administered intravenously at a dosage of 4-5 mg infusion followed by 1-2 g/hour or 4-5 g intramuscularly every 4 hours.
Maximum dose capped at 40 g per 24 hours for seizure prophylaxis in eclampsia.

Anticonvulsant Classes

Three major classes are Hydantoins, Iminostilbenes, and Succinimides.
Phenytoin is the prototype drug in the Hydantoins category.

Hydantoins Overview

Includes Phenytoin, Ethotoin, and Fosphenytoin.
Mode of action involves inhibiting and stabilizing electrical discharges in the motor cortex by affecting ion exchanges during depolarization and repolarization.
Demonstrates antiarrhythmic properties and effectively crosses the blood-brain barrier.

Clinical Uses of Phenytoin

Utilized in neurosurgery to manage seizures.
Effective for controlling status epilepticus after benzodiazepines and for partial and generalized seizures.

Pharmacokinetics of Hydantoins

Exhibits slow onset; peak effect within 1.5-3 hours (rapid release) or 4-12 hours (extended release).
Duration of action lasts approximately 5 hours with a half-life ranging from 6 to 24 hours, highly protein-bound (87-93%).

Pharmacotherapeutics and Contraindications

Monitor for hypersensitivity reactions, potential hepatitis, rash, and arthralgia.
Contraindicated in sinus bradycardia, sinoatrial block, and any severe atrioventricular block.

Caution and Adverse Effects

Use with caution in patients with renal or hepatic insufficiency.
Possible adverse effects include agitation, dizziness, gingival hyperplasia, reddish-brown urine, and cognitive changes.

Drug Interactions

Increased plasma levels and effects due to interactions with Allopurinol, Cimetidine, Diazepam, and others.
Drugs that decrease levels and effects include Barbiturates, Carbamazepine, and chronic alcohol use.

Assessment and Monitoring

Monitor for hypersensitivity syndrome symptoms after 3-8 weeks of therapy onset.
Routine assessment of blood count, urinalysis, and liver function is critical before initiating treatment.

Therapeutic Range

The therapeutic range for hydantoin drugs is 10-20 mcg/ml, ensuring effective and safe medication management.

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Explore the essential roles of magnesium in the body with these flashcards. Learn how magnesium affects acetylcholine levels and its importance for cell function. Test your knowledge on the biochemical actions of magnesium.