Medications Affecting the Nervous System (Part 3)

nervous-1Medications 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.

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


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


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


Use IV route for status epilepticus



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)


CI: marrow suppression / bleeding disorders


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


Avoid in children younger than 3 (hepatotoxicity)
Liver disorders


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)


Valium (Antiepileptic)

Therapeutic Uses:

Used in status epilepticus

Examples: Diazepam (Valium)

Adverse Effects:

  • Respiratory depression
  • Anterograde amnesia



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


Status epilepticus

Anesthesia induction

Relief of spasm d/t injury

Adverse Effects:

CNS depression

Physical dependence from long-term use


Pregnancy (D)

Caution ĉ impaired liver or renal function


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


Baclofen: Pregnancy (C)

Caution in patients with impaired liver or renal function.


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


Pregnancy (C)

Caution with impaired liver & renal function


CNS depressants – additive effects

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