Central Nervous System Drugs: Part 1 Autonomic Nervous System Drugs Drugs Used to treat Seizures Drugs Used to treat Parkinson’s Disease Analgesics

Autonomic nervous System Drugs Adrenergic (norepinephrine) Alpha Receptors Beta Receptors Cholinergic (acetylcholine) Nicotinic Receptors Muscarinic Receptors

Classifications Sympathomimetic Parasympathomimetic Adrenergic agonists Adrenergic antagonists/Alpha or beta blockers Parasympathomimetic Cholinergic agonists Cholinergic antagonists/Muscarinic or Nicotinic blockers

Parasympathomimetics Used to treat Myasthenia Gravis pyridostigmine (Mestinon) Use to increase urination bethanechol (Urecholine)

Anticholinergics Atropine: Therapeutic Uses Increased heart rate Bronchodilation Decreased GI Motility Pupil dilation Side Effects – Dry mouth Constipation Urinary retention scopolamine (Hyoscine) benztropine (Cogentin) Note: Therapeutic effects can be side effects. For example, if the person is taking the drug pre-operatively to decrease gastrointestinal secretions, increased heart rate is not a desired/therapeutic effect, it is a side effect.

Sympathomimetics Used to treat respiratory and cardiovascular conditions stimulates heart causes bronchodilation Some drugs are selective for receptor subtypes phenylephrine (Neosynephrine) albuterol (Proventil) epinephrine

Adrenergic Blockers Primarily used for hypertension propranolol (Inderal) metoprolol (Lopressor)

Drugs Used to Treat Seizures Seizure: abnormal electrical activity in the brain Convulsion: Uncontrolled muscle contractions that may accompany seizures Delirium Tremens: Due to alcohol withdrawal

Antiseizure Drugs Affect concentration and movement of sodium, calcium and chloride ions across the neuronal cell membrane Depress excitability of neurons by enhancing GABA receptors. Note: Some neurotransmitters are inhibitory, not stimulating, GABA is one of those.

Classifications Long acting barbiturates First line drug phenobarbitol (Luminal) Produce tolerance and withdrawal Side effects: respiratory depression drowsiness

Benzodiazepines diazepam (Valium) Increase the action of the neurotransmitter GABA (gamma amino butyric acid). Also cause tolerance and withdrawal Used to treat status epilepticus diazepam (Valium) clonazepam (Klonopin)

Phenytoin and Similar Drugs Delay the influx of sodium across the membrane phenytoin (Dilantin) Causes hypertrophy of the gums valproic acid (Depakene) carbamazine (Tegretol)

Succinamides Block calcium channels, decreasing neuronal impulse transmission Ethosuxinimide (Zarontin) Typically used in combination with other drugs May require dosage adjustment of the other anticonvulsants

Drugs Used to Treat Parkinson’s Disease Parkinson’s Disease is caused by the destruction of dopamine producing neurons in the CNS which causes motor disturbances. SX: Akinisia Shuffling gait Pill rolling Mask like face Parkinson's

Drug Therapy Two fold approach Dopaminergic Drugs Enhance dopamine production or replace it Decrease the influence of acetylcholine Dopaminergic Drugs Anticholinergic Drugs

Anticholinergics Used first before the dopaminergics Block the action of acetylcholine thereby restoring the balance Examples: trihexyphenidyl (Artane) Benztropine (Cogentin

Anticholinergic Side Effects Dry mouth, blurred vision, (mydriasis), eye pain (acute glaucoma), photophobia, constipation, urinary retention, tachycardia, orthostatic hypotension, anhidrosis.

Dopaminergics Replace dopamine or restore its action in the brain Examples: levodopa (Laropa) bromcriptine (Parlodel)

Side effects: Dyskinesia

Dementia Causes Alzheimer’s Disease Stroke AIDS Atherosclerosis Medications Parkinson’s Alzheimer's Disease Symptoms caused by loss of acetylcholine Current medications result in only minor improvement

Acetylcholine Function Drugs Ache inhibitors donepezil hydrochloride (Aricept) tacrine (Cognex