Podcast
Questions and Answers
What are the major symptoms of withdrawal from certain medications?
What are the major symptoms of withdrawal from certain medications?
- Headache, nausea, and fatigue
- Seizures, delirium, and hypothermia (correct)
- Increased appetite and weight gain
- Depression, anxiety, and insomnia
Which of the following can develop tolerance due to hepatic microsomal enzyme induction?
Which of the following can develop tolerance due to hepatic microsomal enzyme induction?
- Succinimides
- Benzodiazepines
- Oxazolidinediones
- Barbiturates (correct)
What is the lethality ratio of barbiturates to their hypnotic dose?
What is the lethality ratio of barbiturates to their hypnotic dose?
- About 5 times
- About 20 times
- About 10 times (correct)
- About 15 times
How many substituents are required at the 5-position for barbiturates?
How many substituents are required at the 5-position for barbiturates?
Which medication class is noted for having significant withdrawal symptoms that may last up to two weeks?
Which medication class is noted for having significant withdrawal symptoms that may last up to two weeks?
What is a common effect of barbiturate overdose?
What is a common effect of barbiturate overdose?
Which of the following symptoms is NOT associated with withdrawal from certain medications?
Which of the following symptoms is NOT associated with withdrawal from certain medications?
What duration is tolerance to barbiturates expected to develop?
What duration is tolerance to barbiturates expected to develop?
In which scenario would therapeutic drug monitoring be particularly beneficial?
In which scenario would therapeutic drug monitoring be particularly beneficial?
What is a critical factor to consider when cross-titrating anticonvulsant medications?
What is a critical factor to consider when cross-titrating anticonvulsant medications?
Which consideration might lead to a higher risk of side effects when switching medications?
Which consideration might lead to a higher risk of side effects when switching medications?
What should ideally happen before tapering off an old anticonvulsant medication?
What should ideally happen before tapering off an old anticonvulsant medication?
What principle should guide treatment decisions in medication management?
What principle should guide treatment decisions in medication management?
How many carbon atoms are optimal in the two substituents at position 5?
How many carbon atoms are optimal in the two substituents at position 5?
What effect does having a phenyl group as one of the 5-substituents have?
What effect does having a phenyl group as one of the 5-substituents have?
What is the result of replacing the 2-oxo group with a 2-thio group?
What is the result of replacing the 2-oxo group with a 2-thio group?
What type of duration is associated with the compound after the 2-oxo group is replaced with a 2-thio group?
What type of duration is associated with the compound after the 2-oxo group is replaced with a 2-thio group?
Which of the following is NOT mentioned as an optimal substituent at position 5?
Which of the following is NOT mentioned as an optimal substituent at position 5?
What is the chemical significance of having optimal carbon atoms in the substituents at position 5?
What is the chemical significance of having optimal carbon atoms in the substituents at position 5?
What structural change is indicated to significantly impact drug action duration?
What structural change is indicated to significantly impact drug action duration?
Which group at position 5 is indicated to have a specific impact on the action duration?
Which group at position 5 is indicated to have a specific impact on the action duration?
What is the primary use of Fosphenytoin?
What is the primary use of Fosphenytoin?
What is a significant characteristic of Carbamazepine's metabolism?
What is a significant characteristic of Carbamazepine's metabolism?
Which of the following statements about Carbamazepine is true?
Which of the following statements about Carbamazepine is true?
Which cytochrome P450 enzyme does Carbamazepine primarily induce?
Which cytochrome P450 enzyme does Carbamazepine primarily induce?
What type of drug is Fosphenytoin characterized as?
What type of drug is Fosphenytoin characterized as?
Which of the following is a reason for the past widespread use of barbiturates?
Which of the following is a reason for the past widespread use of barbiturates?
The metabolite epoxide generated from Carbamazepine is known to be:
The metabolite epoxide generated from Carbamazepine is known to be:
Which of the following describes Fosphenytoin’s administration route?
Which of the following describes Fosphenytoin’s administration route?
Why is Carbamazepine considered an autoinducer?
Why is Carbamazepine considered an autoinducer?
What type of activity does the epoxide of Carbamazepine exhibit?
What type of activity does the epoxide of Carbamazepine exhibit?
Which patient populations are indicated to have a consideration for HLA-A*3101 testing?
Which patient populations are indicated to have a consideration for HLA-A*3101 testing?
What is advised for patients with a high initial dose of Lamotrigine?
What is advised for patients with a high initial dose of Lamotrigine?
What is a potential consideration when introducing a second ASM in treatment?
What is a potential consideration when introducing a second ASM in treatment?
Which medications may require careful monitoring when used in combination with Lamotrigine?
Which medications may require careful monitoring when used in combination with Lamotrigine?
What might be a consequence of rapid dose increases of ASM?
What might be a consequence of rapid dose increases of ASM?
In the management of epilepsy, which of the following is true regarding dosage adjustments?
In the management of epilepsy, which of the following is true regarding dosage adjustments?
Which of these is a correct statement about the medication Phenytoin?
Which of these is a correct statement about the medication Phenytoin?
Which populations mentioned are associated with higher sensitivity to HLA-A*3101?
Which populations mentioned are associated with higher sensitivity to HLA-A*3101?
Study Notes
Fosphenytoin
- Fosphenytoin is the prodrug of phenytoin.
- This anticonvulsant is designed for intravenous administration.
- It is used for status epilepticus and seizures occurring during neurosurgery.
Carbamazepine and Oxcarbazepine
- These drugs are useful for various types of seizures.
- Carbamazepine induces various enzymes including 3A4, 1A2, 2B6, 2C19, 2C8, and 2C9.
- It is considered an autoinducer, which means it also induces uridine 5´-diphospho-glucuronosyltransferases (UGTs).
- Carbamazepine’s epoxide is more toxic than carbamazepine.
Barbiturates
- Barbiturates are anticonvulsants that were widely used drugs for inducing sleep in 1958.
- Withdrawal symptoms, such as seizures, delirium, and hypothermia, can persist for up to 2 weeks after discontinuation of the drug.
- Tolerance to barbiturates develops within 2 weeks of treatment due to the induction of hepatic microsomal enzymes.
- The lethal dose of barbiturates is approximately 10 times the hypnotic dose.
- Barbiturates require two substituents at the 5-position of the molecule.
- Optimal total number of carbon atoms in the two 5-substituents is 5-7.
- A phenyl group at the 5-position increases the duration of action.
- Replacing the 2-oxo group with a 2-thio group (change in oxygen to sulfur) results in a significantly shorter duration of action.
Therapeutic Drug Monitoring (TDM)
- TDM can be useful in cases of suspected toxicity, suspected drug interactions, pregnancy, critical illness, and if the patient is taking phenytoin.
- TDM may be used in formulation or generic substitution.
- It is important not to over-rely on numbers and rather focus on the needs of the patient.
Strategies for Cross-titrating Anti-Seizure Medications (ASMs)
- The strategy for cross-titrating ASMs depends on multiple factors.
- Determine the reason for switching medications.
- Consider the patient's sensitivity to medication changes and adherence to the prescribed regimen.Â
- Assess if the new medication belongs to the same drug class as the old medication.
- The goal is to reach the desired dose of the new ASM before tapering the old medication.
- Fast tapering of ASMs increases risk of breakthrough seizures.
- It is essential to monitor the patient for side effects, especially if the new medication is in a different class.
- Patients with HLA-A*3101 are more likely to experience Stevens-Johnson syndrome when taking lamotrigine.
- Higher initial doses of lamotrigine, rapid dose increases, and co-administration with valproic acid increase the risk of Stevens-Johnson syndrome.
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Description
This quiz covers key anticonvulsant medications including Fosphenytoin, Carbamazepine, and Barbiturates. Learn about their uses, mechanisms, and potential side effects. Test your knowledge on these important drugs in the management of seizures.
