Test #29 (PRR Week 2N Block 12: Neuro Pharm)

Question 1

Explain blood gas/partition coefficient of gas anesthetic & what it means in terms of drug properties

Answer 1

Onset of action of a gas anesthetic depend on its solubility in blood (blood/gas partition coefficient). Drugs with high blood/gas partition coefficients are more soluble in the blood, demonstrate slower equilibration with brain, & have longer onset times

Question 2

Classify first generation antipsychotics based on characteristic side effect profiles

Answer 2

Low potency: non-neurologic side effects (e.g., sedation, anticholinergic side effects, orthostatic hypotension); High-potency: extrapyramidal sx (Think: “Potency = ExtraPyramidal)

Question 3

Explain/Dx: 55 yo man with chest pain while watching tv, PMH of htn, asthma, diabetes, smokes 2 packs cigs daily, tx in ED for chest pain & becomes short of breath, bp now 135/85 mmHg and heart rate 65/min, PE reveals prolonged expirations and wheezes in bilateral lung fields

Answer 3

Beta-adrenergic blockade reduces blood pressure and cardiac work, which is beneficial in acute tx of myocardial iscemia. However, when noncardioselective agents used, adverse effects like bronchoconstriction (dose-dependent) may be seen

Question 4

(1) Dx: 55 yo farmer confused disoriented, otherwise healthy, not use any meds, bp 110/70 mmHg, HR 50/min, pupils symmetric, 2 mm, and reactive to light, tearing considerably, scattered wheezes bilaterally on lung auscultation, patient’s skin flusedhed and sweating profusely (2) Explain

Answer 4

(1) Organophosphate poisoning (2) Exposure to certain insecticides => organophosphate poisoning. Profound and prolonged cholinesterase inhibition because organophosphates bind irreversibly to cholinesterase, causing state of cholinergic excess: excessive salivation, lacrimation, diaphoresis, urinary incontinence, diarrhea, emesis, miosis, and bradycardia

Question 5

(1) Mechanism of Benzodiazepines (2) Other drugs sharing this mechanism

Answer 5

(1) Allosteric binding to GABA receptor (2) Benzodiazepines, Barbiturates, and alcohol all bind to different components of GAGAa receptor & facilitate inhibitory action of GAGA. Note: GABAa & GAGAc = ion channels while GABAb receptor = G-protein linked

Question 6

(1) Mechanism of Timolol (2) Explain its use in glaucoma

Answer 6

(1) Beta-blocker (2) Glaucoma due to increased intraocular pressure, due to decreased outflow or increased production of aqueous humor. Timolol and other beta-blockers decrease aq. hum. prod. by ciliary epithelium

Question 7

(1) List 1st and 2nd generation H1 blockers. (2) Which given to patient with hx of falls, and why?

Answer 7

(1) 1st generation: Diphenhydramine, dimenhydrinate, chlorpheniramine; 2nd generation: Loratadine, Fexofenadine, Desloratidine, Cetirizine (2) 2nd generation, because have minimal sedative (and antimuscarinic) effects

Question 8

(1) Tx: patient complains of weakness in right arm and leg 5 days after resolve of subarachnoid hemorrhage

Answer 8

Calcium channel blockers (espeically Nimodipine) can be used to assist in prevention of cerebral vascular spasm following SAH. This is an alternative use of calcium channel blockers.

Question 9

(1) Contraindicated drug in this patient: 65 yo male undergoing rehabilitation after stroke, given diazepam in order to decrease muscle spasticity involved extremities (2) Explain

Answer 9

(1) 1st generation H1-histamine receptor antagonists, including diphenydramine and chlorpheniramine, (2) can cause significant sedation, especially when used with other meds that cause CNS depression (e.g., benzodiazepines)

Question 10

(1) Compare side effect profile of SSRIs to TCAs (2) Relatively common side effect of SSRIs

Answer 10

(1) Better side effect profile (2) Sexual dysfunction relatively common side effect of SSRIs & limits use in many patients

Question 11

Indication of clinical movement after edrophonium administration in myasthenia gravis patients

Answer 11

Clinical movement after edrophonium admin. indicates that pt. is undertreated (myasthenic crisis)

Question 12

Barbiturates effect on warfarin therapy

Answer 12

Barbiturates induce hepatic microsomal enzymes, increase warfarin metabolism and reducing its anticoagulation activity

Question 13

(1) Dx: 15 yo male, 3 mo. hx periodic, sudden-onset, arrhythmic jerking movements, muscle contractions usually happen early in AM, soon after wakening, aggravated by sleep deprivation, movements neither suppressible nor preceded by an urge to make a movement, never lost consciousness, no other PMH, family hx reveals seizure disorder in uncle (2) Tx of choice & its mechanism

Answer 13

(1) Myoclonic seizure (2) Sodium valproate (valproic acid) is drug of choice for myoclonic seizures. This drug suppresses abnormal electric activity in cortex by affecting GABA and NMDA receptors, as well as Na+ and K+ channels

Question 14

Meds causing seizures

Answer 14

Bupropion (antidepressant), Clozapine (antipsychotic at high doses), Isoniazid (anti-tuberculosis drug, if given without pyridoxine), Ciprofloxacin (antibiotic), & imipenem (antibiotic)

Question 15

(1) Dx: 8 yo Asian immigrant, brief loss of consciousness, fell on floor & ‘started shaking and jerking’, also seen ‘staring in space’ that occurs several times a day for last year, boy seems sleepy although oriented in time and place, several hours later, alert & wants to go home (2) Tx of choice

Answer 15

(1) Absence & associated tonic-clonic seizures (2) Sodium valproate

Question 16

Mechanisms of following: (1) Anticholinergic poisoning (2) Botulism (3) Organophosphate toxicity

Answer 16

(1) Inhibit postsynaptic action of acetylcholine (2) Blocks presynaptic exocytosis of acetylcholine vesicles (3) Prevent degradation of acetylcholine within synaptic cleft

Question 17

(1) Mechanism of most opioid narcotics (2) Purpose & mechanism of Pentazocine (3) Warning about Pentazocine use

Answer 17

(1) Majority of opioid narcotics selective mu receptor agonists that work by binding to mu receptors and mimicking effects of endogenous opioid receptors (2) Opioid narcotic specifically designed to produce analgesic effects with little to nose abuse potential. Pharmacologically, works through partial agonist activity and weak antagonist activity at mu receptors. (3) Because of its weak antagonistic effects, can cause withdrawal sx in patients who are dependent or tolerant to morphine or other opioids

Question 18

Entacapone: (1) Type of drug (2) Mechanism (3) Other drug in this type/class

Answer 18

(1) Catechol-O-methyl transferase (COMT) inhibitor (2) Increase levodopa availability in brain (3) Tolcapone

Question 19

(1) Type of drug amitriptyline is (2) Most common cause of death in patients with this kind of drug overdose (3) Explain (4) Intervention

Answer 19

(1) TCA (2) Refractory hypotension & cardiac arrhythmias (3) Inhibition of fast sodium channels in cardiac myocytes (and His-Purkinje system) is thought to be major underlying cellular event. (4) Fluid resuscitation with normal saline and hypertonic sodium bicarbonate administration are crucial in these patients

Question 20

(1) Halothane toxicity (2) Mechanism (3) Clinical/Lab finding

Answer 20

(1) Massive hepatic necrosis is rare but severe complication of halothane exposure (2) Occurs due to direct liver injury by halothane metabolites & formation of autoantibodies against liver proteins (3) Light microscopy shows massive centrilobular hepatic necrosis.

Question 21

(1) type of drug amitriptyline is (2) Comparison of its and similar drugs’ anticholinergic properties to other drugs (3) Patient population to take caution with using this drug & why

Answer 21

(1) TCAs such as imipramine, doxepin, amitriptylin, and clomipramine have (2) stronger anticholinergic properties than heterocyclics or SSRIs & (3) should be used with caution in pts with benign prostatic hyperplasia (BPH), as they may cause urinary retention

Question 22

Mechanism of resistance against cephalosporins

Answer 22

Change in structure of penicillin binding proteins