USMLE (Fach) / Pharmacology - Neurology (Lektion)

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• Glaucoma drugs α-agonists:Epinephrine (α1): ↓ aqueous humor synthesis via vasoconstrictionBrimonidine, apraclonidine (α2): ↓ aqueous humor synthesis- Mydriasis (α1); do not use in closed-angle glaucoma.- ...
• Opioid analgesics Mechanism: Act as agonists at opioid receptors (μ = β-endorphin, δ = enkephalin, κ = dynorphin) to modulate synaptic transmission – close presynaptic Ca2+ channel, open postsynaptic K+ channels → ↓ ...
• Pentazocine κ-(dynorphin) opioid receptor agonist and μ-(β-endorphin) opioid receptor antagonist or partial agonist. Clincal use: Analgesia for moderate to severe pain. Adverse effects: Can cause opioid withdrawal ...
• Butorphanol κ-(dynorphin) opioid receptor agonist and μ-(β-endorphin) opioid receptor partial agonist. Clinical use: Severe pain (eg, migraine, labor). Causes less respiratory depression than full opioid agonists. ...
• Tramadol Mechanism: very weak opioid agonist, also inhibits 5-HT receptors. Clincial use: Chronic pain. Adverse effects: Similar to opioids. Decreases seizure threshold. Serotonin syndrome.
• Barbiturates Phenobarbital, pentobarbital, thiopental, secobarbital Mechanism: Facilitate GABAA action by ↑ duration of Cl- channel opening. (barbidurates ↑ duration).  Clinical use: Sedative for anxiety, seizures, ...
• Benzodiazepines Diazepam, lorazepam, triazolam, temazepam, oxazepam, midazolam, chlordiazeproxide, alprazolam Mechanism: Facilitate GABAA action by ↑ frequency of Cl- channel opening. ↓ REM sleep. Most have long ...
• Nonbenzodiazepine hypnotics Zolpidem, zaleplon, eszopiclone Mechanism: Act via the BZ1 subtype of the GABA receptor. Effects reversed by flumazenil. Sleep cycle less affected as compared with benzodiazepine hypnotics. Clinical use: ...
• Inhaled anesthetics Desflurane, halothane, enflurane, isoflurane, sevoflurane, methoxyflurane, N2O. Mechanism unknown Effects: myocardial depression, respiratory depression, nausea/emesis, ↑ cerebral blood flow (↓ cerebral ...
• Intravenous anesthetics Thiopental (Facilitate GABAA, barbiturate): Used for induction of anesthesia and short surgical procedures. ↓ Cerebral blood flow. High lipid solubility. Effect terminated by rapid redistribution into ...
• Local anesthetics Esters – procaine, cocaine, tetracaine, benzocaine, chloroprocaine.Amides – lidocaine, mepivacaine, bupivacaine, ropivacaine (amides have 2 i's in name). Mechanism: Block Na+ channels by binding to ...
• Neuromuscular blocking drugs Muscle paralysis in surgery or mechanical ventilation. Selective for Nm nicotinic receptors at neuromuscular junction but not autonomic Nn receptors. Depolarizing: Succinylcholine – strong ACh receptor ...
• Dantrolene Prevents release of Ca2+ from the sarcoplasmatic reticulum of skeletal muscle by binding to the ryanodine receptor. Clinical use: Malignant hyperthermia (a toxicity of inhaled anesthetics and succinylcholine) ...
• Baclofen Skeletal muscle relaxant. GABAB receptor agonist in spinal cord. Clinical use: Muscle spasticity, dystonia, multiple sclerosis.
• Cyclobenzaprine Skeletal muscle relaxant. Acts within CNS. Clincal use: Muscle spasms. Adverse effects: Anticholinergic side effects. Sedation.
• Parkinson disease drugs Parkinsonism is due to loss of dopaminergic neurons and excess cholinergic activity Dopamine agonists:- Ergot – Bromocriptine - Non-ergot (preferred) – pramipexole, ropinirole; toxicity includes ...
• Dopamine agonists Parkinson disease drug Ergot – BromocriptineNon-ergot (preferred) – Pramipexole, ropinirole - Toxicity includes impulse control disorder (eg, gambling), postural hypotension, hallucinations/confusion. ...
• Benztropine Antimuscarinic - curbs excess cholinergic activity in Parkinson disease - improves tremor and rigidity but has little effect on bradykinesia
• Levodopa/carbidopa Prevent peripheral (pre-BBB) L-DOPA degradation → ↑ L-DOPA entering CNS → ↑ central L-DOPA available for conversion to dopamine. Unlike dopamine, L-DOPA can cross blood-brain barrier and is converted ...
• Selegiline, rasagiline Act centrally (post-BBB).Selectively inhibit MAO-B (metabolize dopamine) → ↑ dopamine availability. Clinical use: Adjunctive agent to L-DOPA to reduce motor fluctuations in Parkinson disease Adverse ...
• Alzheimer disease drugs Memantine:- NMDA receptor antagonist; helps prevent excitotoxicity (mediated by Ca2+).- Adverse defects: Dizziness, confusion, hallucinations. Donepezil, galantamine, rivastigmine:- AChE inhibitors.- ...
• Huntington disease drugs Tetrabenazine and reserpine - inhibit vesicular monoamine transporter (VMAT) --> ↓ dopamine vesicle packaging and release Haloperidol - D2 receptor antagonist
• Riluzole ↓ neuron glutamate excitotoxicity  Clinical use: ALS, ↑ survival
• Triptans Sumatriptan Mechanism: 5-HT1A/1D agonists. Inhibit trigeminal nerve activation; prevent vasoactive peptide release; induce vasoconstriction. Clinical use: Acute migrane, cluster headache attacks Adverse ...
• Acetazolamide Diuretic ↓ aqueous humor synthesis via inhibition of carbonic anhydrase
• Pilocarpine Direct cholinomimetic ↑ outflow of aqueous humor via contraction of ciliary muscle and opening of trabecular meshwork - use in emergencies - very effective at opening meshwork into canal of Schlemm ...
• Carbachol Direct cholinomimetic ↑ outflow of aqueous humor via contraction of ciliary muscle and opening of trabecular meshwork Side effects: Miosis and cyclospasm (contraction of ciliary muscle)
• Physostigmine Indirect cholinomimetic ↑ outflow of aqueous humor via contraction of ciliary muscle and opening of trabecular meshwork Side effects: Miosis and cyclospasm (contraction of ciliary muscle)
• Lantanoprost (PGF2α) ↑ outflow of aqueous humor Side effects: darkens color of iris (browning)
• Phenytoin, fosphenytoin Na+ channel inactivation; zero-order kinetics. Clinical use: - 1st line for recurrent seizure prophylaxis- Tonic-clonic seizures- Partial (focal) seizures- Also a class IB antiarrhythmic. Side effects:- ...
• Carbamazepine Epilepsy drug Blocks Na+ channels Indication:- 1st line for trigeminal neuralgia- Partial (focal) and tonic-clonic seizures Side effects: Diplopia, ataxia, blood dyscrasias (agranulocytosis, aplastic ...
• Lamotrigine Blocks voltage-gated Na+ channels, inhibits the release of glutamate.  Indication:- Partial (focal) seizures- Tonic-clonic seizures- Absence Side effects: Stevens-Johnson syndrome (must be titrated slowly) ...
• Gabapentin Primarily inhibits high-voltage-activated Ca2+ channels; designed as GABA analog. Indication:- Partial (focal) seizures- Also used for peripheral neuropathy, postherpetic neuralgia Side effects: Sedation, ...
• Topiramate Blocks Na+ channels, ↑ GABA action Indications:- Partial (focal) seizures- Tonic-clonic seizures- Also used for migraine prevention Side effects: Sedation, mental dulling, word-finding difficulty, ...
• Phenobarbital ↑ GABAA action Indication:- 1st line in neonates- Partial (focal) seizures- Tonic-clonic seizures- Status epilepticus Side effects: - Sedation, tolerance, dependence, induction of cytochrome P-450, ...
• Valproic acid ↑ Na+ channel inactivation, ↑ GABA concentration by inhibiting GABA transaminase. Indication:- Broad-spectrum- Tonic-clonic seizures- Partial (focal) seizures- Absences- Also used for myoclonic ...
• Ethosuximide Blocks thalamic T-type Ca2+ channels Indication:- 1st line for absences (less hepatotoxicity than valproic acid) Side effects:- GI distress, fatigue, headache, itching and urticaria, Stevens-Johnson ...
• Tiagabine ↑ GABA by inhibiting reuptake Indication:- Partial (focal) seizures
• Vigabatrin Irreversible GABA transaminase inhibitor → ↑ GABA.Vigabatrin Indication:- Partial (focal) seizures Side effects: Permanent visual loss (black box warning)
• Levetiracetam Binds to synaptic vesicle protein (SV2A) to modulate release of GABA and glutamate neurotransmitters. Indication:- Partial (focal) seizures- Tonic-clonic seizures Side effects: Neuropsychiatric symptoms ...
• Sumatriptan 5-HT agonist - inhibits trigeminal nerve activation; prevents vasoactive peptide release; induces vasoconstriction Clinical use: acute migraine, cluster headache attacks Toxicity: coronary vasospasm
• Suvorexant Orexin (hypocretin) receptor antagonist Clinical use: Insomnia Adverse effects: CNS depression, headache, dizziness, abnormal dreams, upper respiratory tract infection. - Contraindicated in patients with ...
• Ramelteon Melatonin receptor agonist, binds MT1 and MT2 in suprachiasmatic nucleus. Clincal use: Insomnia Adverse effects: Dizziness, nausea, fatigue, headache. No dependence.
• Amantadine Parkinson disease drug. ↑ dopamine release and ↓ dopamine reuptake. Side effects:- Ataxia- Livedo reticularis - Edema
• Tetrabenazine, reserpine Inhibit vesicular monoamine transporter (VMAT) dopamine → decreased vesicle packaging and release. Clinical use: Huntington disease, tardive dyskinesia.
• Ketamine NMDA receptor antagonist Use: Dissociative anesthesia. Sympathomimetic.  Increases cerebral blood flow. Emergence reaction possible with disorientation, hallucination, vivid dreams
• Propofol Potentiates GABAA Use: Rapid anesthesia induction, short procedures, ICU sedation
• Midazolam Facilitates GABAA (benzodiazepine) Use: Procedural sedation (eg, endoscopy), anesthesia induction  May cause postoperative respiratory depression, hypotension, anterograde amnesia 
• Anesthetics – general principles CNS drugs must be lipid soluble (cross the BBB) or be actively transported. Drugs with ↓ solubility in blood = rapid induction and recovery times.Drugs with ↑ solubility in lipids = ↑ potency ...
• Tizanidine α2 agonist - Effective as monotherapy for the treatment of spasticity, eg in multiple sclerosis

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