Medications Affecting the Nervous System (Part 3)

Medications Affecting the Nervous System (Part 3)

CI = Contraindicated

Ĉ = With

Here is a site that lists the different categories of pregnancy / drug interactions – it includes a nice image of Pregnancy A,B,C, D restrictions.

http://www.merckmanuals.com/home/women-s-health-issues/drug-use-during-pregnancy/drug-use-during-pregnancy

Antiepileptic Medications

(Medication List)

• Barbiturates……………………….. phenobarbital (Luminal)
• Hydantoins phenytoin (Dilantin)
• Benzodiazepines……………………….. diazepam (Valium)
• Lorazepam (Ativan
• Carbamazepine (Tegretol)
• Ethosuximide (Zarontin)
• Valproic acid (Depakote)
• Gabapentin (Neurontin)

Other meds

• lamotrigine (Lamictal)
• clonazepam (Klonopin)

Mechanisms (how the drugs work)

Slow Ca²⁺ and Na⁺ reentry to neuron

Potentiating inhibitory effect of (GABA)

Suppress neuron firing

Barbiturate (Antiepileptic)

Therapeutic Uses:

• Partial seizures and generalized tonic-clonic seizures
• Not effective against absence seizures

Examples: Phenobarbital (Luminal)

Adverse Effects:

CNS effects: Adults as sedation and anxiety, kids as irritability and hyperactivity

Toxicity: Nystagmus, ataxia, respiratory depression, pinpoint pupils

Hydantoins (Antiepileptic)

Therapeutic Uses:

Effective against all major forms except absence seizures

Examples: Phenytoin (Dilantin)

Adverse Effects:

CNS effects, Skin rash, Teratogenic, Gingival hyperplasia, Cardiovascular, Endocrine effects, Vitamin D metabolism

Contraindications/Precautions:

CI: sinus bradycardia, SA blocks, 2^nd & 3^rd degree AV blocks

Interactions:

Oral contraceptives, warfarin, glucocorticoids: decrease absorption of these

EtOH, diazepam, cimetidine, valproic acid: increase phenytoin levels

Carbamazepine, phenobarbital, chronic EtOH: decrease phenytoin levels

CNS depressants (e.g. barbiturates/EtOH): Additive effects with concurrent use

Education:

Use IV route for status epilepticus

Antidysrhythmics

Carbamazepine (Antiepileptic)

Therapeutic Uses:

Partial seizures, tonic-clonic seizures, bipolar disorder, trigeminal neuralgia

Examples: Tegretol

Adverse Effects:

Skin disorders, Cognitive function is minimally affected but CNS effects can occur, Blood dyscrasias, Teratogenic, Hypo-osmolarity (increase ADH secretion)

Contraindications/Precautions:

CI: marrow suppression / bleeding disorders

Interactions:

Grapefruit juice: inhibits metabolism increase [carbamazepine]

Phenytoin & phenobarbital: decreased η carbamazepine

Oral contraceptives and warfarin: Carbamazepine stimulates hepatic enzymes which ò levels of these medications

Ethosuximide (Antiepileptic)

Therapeutic Uses:

Indicated ONLY for absence seizures

Examples: Zarontin

Adverse Effects:

• GI effects (take ĉ food)

CNS effects (fatigue, dizziness)

Valproic Acid (Antiepileptic)

Therapeutic Uses:

Partial, generalized, and absence seizures, bipolar disorder, and migraines

Examples: Depakote

Adverse Effects:

GI effects (take ĉ food), Hepatotoxicity, Thrombocytopenia, Pancreatitis as evidenced by nausea, vomiting, and abdominal pain

Contraindications/Precautions:

Avoid in children younger than 3 (hepatotoxicity)
Liver disorders

Interactions:

Phenytoin and phenobarbital: Concurrent use ñ these medications

Gabapentin (Antiepileptic)

Therapeutic Uses:

Single agent used for partial seizures

Neuropathic pain

Migraine prev.

Adverse Effects:

CNS effects (drowsiness, nystagmus)

Benzodiazepines

Valium (Antiepileptic)

Therapeutic Uses:

Used in status epilepticus

Examples: Diazepam (Valium)

Adverse Effects:

• Respiratory depression
• Anterograde amnesia

Teratogenic

Muscle Relaxants / Antispasmodics (Medication List)

Centrally Acting Muscle Relaxants

Diazepam (valium)

Cyclobenzaprine (Flexeril)

Baclofen (Lioresal)

Metaxalone (Skelaxin)

Peripherally Acting Muscle Relaxants

Dantrolene (Dantrium)

Diazepam (Muscle Relaxant / Antispasmodic)

Expected Action:

• Acts in CNS to enhance GABA and produce sedation

Acts in CNS to depress spasticity of muscles

Therapeutic Uses:

Relief of spasticity d/t Cerebral Palsy or MS

Anxiety & panic disorders

EtOH withdrawal

Insomnia

Status epilepticus

Anesthesia induction

Relief of spasm d/t injury

Adverse Effects:

CNS depression

Physical dependence from long-term use

Contraindications/Precautions:

Pregnancy (D)

Caution ĉ impaired liver or renal function

Interactions:

CNS depressants (EtOH, opioids, antihistamines, barbiturates): Additive CNS depressive effects with concurrent use. Centrally Acting

(Muscle Relaxant / Antispasmodic)

Expected Action:

Acts in CNS to depress spasticity of muscles

Examples: Baclofen, cyclobenzaprine, metaxalone

Therapeutic Uses:

Relief of muscle spasm d/t injury

Relief of spasticity r/t cerebral palsy or multiple sclerosis

Adverse Effects:

CNS depression

Physical dependence from long-term use

Metaxalone: hepatotoxicity

Baclofen: nausea, urinary retention, constipation

Contraindications/Precautions:

Baclofen: Pregnancy (C)

Caution in patients with impaired liver or renal function.

Interactions:

CNS depressants (EtOH, opioids, antihistamines) – additive CNS depressant effects with concurrent use.

Peripherally Acting (Muscle Relaxant / Antispasmodic)

Expected Action:

Only peripherally acting muscle relaxant. Inhibits muscle contraction by preventing release of calcium in skeletal muscles.

Name: Dantrolene (Dantrium)

Therapeutic Uses:

• Relief of spasticity d/t cerebral palsy or multiple sclerosis

Treatment of malignant hyperthermia

Adverse Effects:

CNS depression

Hepatic toxicity

Contraindications/Precautions:

Pregnancy (C)

Caution with impaired liver & renal function

Interactions:

CNS depressants – additive effects