Pharmacology Flashcards
What antiemetic should MOST be avoided in patients undergoing assisted reproductive therapy?
Metoclopramide
Along with droperidol, metoclopramide is avoided in the assisted reproductive therapy population because it can cause increased prolactin levels. High prolactin levels have been shown to impair follicle maturation and corpus luteum function, decreasing the likelihood of a successful reproductive outcome.
The highest serum fluoride levels are seen following the administration of which volatile anesthetic?
Sevoflurane
How is mivacurium metabolized?
It undergoes hydrolysis by plasma cholinesterase at a rate equivalent to 88% that of succinylcholine
It therefore, would have a prolonged duration of action in a patient who is homozygous for atypical plasma cholinesterase
What are the common side effects of anticholinergics?
Hot as a hare: increased body temperature
Blind as a bat: mydriasis (dilated pupils)
Dry as a bone: dry mouth, dry eyes, decreased sweat
Red as a beet: flushed face
Mad as a hatter: delirium
Decreased intestinal motility and peristalsis (constipation)
Lower esophageal sphincter pressure is reduced
What is an adverse effect of prolonged intravenous administration of nitroglycerin?
Methemoglobinemia, which causes a false reading of SaO2 of 85% (whether the patient’s saturation is higher or lower)
Systemic opioids modify pain through action at what neurological site?
The substantia gelatinosa
What are the special characteristics of alfentanil’s pharmokinetics.
It has a very small volume of distribution, which is why it has a short elimination half-life (1.5 hr)
What are the manifestations of anthrax poisoning?
It is an influenza-like disease with cough, myalgia,fever and malaise.
After a few days, the patient improves, but the a couple of days later, the patient becomes much sicker with dyspnea, cyanosis, hemoptysis, stridor, and chest pain.
What is the most notable finding on CXR for anthrax exposure?
Widened mediastinum
What is the treatment for anthrax?
Ciprofloxacin and doxycycline
(Penicillin G was the treatment of choice, but weaponized anthrax has been engineered to be resistant to this medication)
What is the bacteriology of anthrax?
It is a gram-positive, spore-forming bacillus that is transmitted to humans from contaminated animals and their carcasses.
Inhalational anthrax is rare but has an 80% mortality rate.
Describe the 2 types of HIT. How is it diagnosed?
1) Mild form: shows a transient decrease in platelet count after heparin exposure.
2) Severe form: autoimmune-mediated, with IgG antibodies to heparin and platelet factor IV.
Diagnosis is made my observing a 50% drop in platelets after heparin exposure, recovery after discontinuation of heparin, and exclusion of other causes and confirmation of antibodies.
Methadone (potency vs. Morphine; where does it act; what ECG changes can it cause)
It is 3 times as potent as morphine
It can also act on NMDA receptors (mu receptors as well)
It can cause a prolongation of the QT interval
What effects does acute vs. chronic use of cocaine have on MAC?
Acute use of cocaine increases MAC, due to increased sympathetic discharge, which can lead to coronary spasm and STEMI
Chronic use does not affect MAC. Synaptic catecholamines are spent with chronic use and indirect pressors like Ephedrine are often ineffective in increasing the blood pressure
What does magnesium do at the neuromuscular junction?
It antagonizes the release of acetylcholine at the neuromuscular junction and therefore, potentiates both depolarizing and non depolarizing neuromuscular paralytics
What common medication lowers the activity of the plasma cholinesterase?
Medications that inhibit pseudocholinesterase are: neostigmine cyclophosphamide phenelzine pancuronium esmolol metoclopramide monoamine oxidase inhibitors (MAOIs) oral contraceptives
What dose of the benzocaine can cause methemoglobinemia?
Doses > 200-300mg
What effects does terbutaline have on electrolytes?
It is a beta1 & 2 agonist, with predominantly beta 2 properties. It therefore produces hyperglycemia, hypokalemia, and tachycardia
What effect does clonidine have on blood glucose?
Clonidine improves blood glucose control and decreases insulin requirements during surgery in type II diabetics by inhibiting sympathoadrenal activity as an alpha-2 agonist
How does Cimetidine effect hepatic drug metabolism? Name other drugs that are similar in effect.
It inhibits hepatic drug metabolism
Ketoconazole
Erythromycin
Disulfiram
Ritonavir
What are some common drugs that increase/promote hepatic drug metabolism?
Phenobarbital Phenytoin Rifampin Carbamazepine Ethanol
Which volatile anesthetic has the largest impact on global warming?
Desflurane has the highest potential to produce global warming (although all anesthetics are recognized as greenhouse gases)
Sevoflurane and Isoflurane may contribute almost equally when used in conjunction with high fresh gas flow rates and 60% nitrous oxide.
What drugs cause a histamine release and transient hypotension?
Morphine Atracurium Mivacurium Doxacurium d-tubocurarine
Because all of these drugs possess the benyzlisoquinoline structure
What effect does lithium have on anesthetic drugs?
Lithium decreases anesthetic requirements & interferes with the action of several anesthetic agents.
It prolongs the effects of barbiturates, benzodiazepines, succinylcholine and non depolarizing muscle relaxants.
It blocks the effect of ADH on the renal tubules
It can produce hypokalemia and hypercalcemia
What drugs are myotoxic?
Statins, carbon monoxide (CO), ethylene glycol, seizures, cocaine, and colchicine
What drug induces serotonin release, inhibits the reuptake of norepinephrine, antagonizes NMDA receptors, and has opioid-like activity?
Tramadol
What physiologically occurs when phenylephrine is given to a patient?
Efferent signals respond (to the increased pressure detected by baroreceptors found in the carotid sinus and aortic arch) by decreasing sympathetic activity, leading to decreased cardiac contractility, heart rate, and vascular tone.
What are some drugs that have a first-pass effect in the liver?
Metoprolol
Diphenhydramine
Lidocaine
What diuretic causes metabolic acidosis?
Acetazolamide, which is a carbonic anhydrase (CA) inhibitor that acts at the proximal convoluted tubule of the kidney, interfering with bicarbonate and sodium reabsorption, which cases a hyperchloremic metabolic acidosis.
What diuretic(s) cause metabolic alkalosis?
1) Loop diuretics such as furosemide and torsemide, which inhibit a Na+/K+ ATPase that ultimately results in loss of sodium, potassium, chloride, hydrogen ion, magnesium, and calcium.
2) HCTZ and metolazone both work at the distal convoluted tubule and inhibit NaCl cotransporter mechanism that results in the loss of sodium, potassium, chloride, hydrogen ion, and preservation of calcium (hypercalcemia).
How is chloroprocaine metabolized?
It is an ester local anesthetic metabolized by pseudocholinesterase.
How is esmolol metabolized?
By red cell esterase (NOT plasma-cholinesterase)
What drugs can lead to postoperative jaundice?
Acetaminophen Cephalosporins NSAIDs Insulin Contrast media Procainamide Thiopental Ranitidine Hydralazine
What drugs have been shown to decrease MAC?
Clonidine Lithium Opioids Barbiturates Lidocaine Neostigmine Pancuronium Hydroxyzine Ketamine Verapamil
What herbal medication can decrease the hepatic metabolism of anesthetic agents and cause delayed emergence?
St. John’s Wort, which is frequently take for anxiety, insomnia, and depression
Side effects include:
hepatic enzyme induction
prolonged anesthesia
decreased metabolism of digoxin, warfarin, anticonvulsants and cyclosporin
What is licorice used for as an herbal medication? Side effects?
Gastritis and duodenal ulcers
Side effects:
Hypertension
Hypokalemia
Edema
Medicinal benefits of Purple Cone Flower? Side effects?
Treatment of burns, wounds, UTIs, and cough
Side effects:
Decrease corticosteroid effects
Medicinal benefits of Goldenseal? Side Effects?
It is used as a diuretic, anti-inflammatory, laxative, and hemostatic effects
Side effects: Ototoxicity Paralysis in overdose Edema Hypertension
What are the 4 ways to prevent platelet aggregation?
1) Cyclooxygenase inhibition (i.e. Aspirin) - lasts for the life of the platelet
2) Phosphodiesterase inhibition increases cyclic AMP and decreases platelet aggregation
3) Inhibition of the ADP receptor, and therefore blocking ADP-induced platelet aggregation (i.e. Ticlopidine and Clopidogrel)
4) Inhibition of glycoprotein IIb/IIIa receptors (i.e. abciximab and tirofiban)
Describe the symptoms of Digoxin toxicity
It characteristically produces transient numbness, tingling, and altered yellow vision with nausea and vomiting.
Which volatile anesthetic gas produces the most carbon monoxide (CO) by reacting with carbon dioxide (CO2) absorbents?
Desflurane
(When CO2 absorbents are maintained at or above room temperature, Desflurane under 1 MAC produces 8,000 ppm CO compared to Sevoflurane at 2 MAC, which produces 79 ppm CO.)
What properties of Cisatracurium make it appealing to use in ICU patients?
Its Elimination does NOT depend on end-organ function
Its metabolism depends on Hoffman elimination as well as ester hydrolysis
Hetastarch interferes with coagulation by decreasing the levels of which blood factor/component?
One liter of 6% Hetastarch decreases the levels of factor VIII by 50% and prolongs the aPTT
What is the half life of nitric oxide?
Less than 5 seconds
List the names of some common Angiotensin Receptor Blockers (ARBs)
Candesartan
Losartan
Valsartan
Act as vasodilators
What is the MOA of Trimethaphan
It is a vasodilator that is a ganglionic blocker
Name some common DIRECT vasodilators
Calcium channel blockers Hydralazine Minoxidil Nitroglycerin Nitroprusside Trimethaphan
List some common alpha-adrenergic blockers
Labetalol
Phentolamine
Prazosin
Terazosin
Act as vasodilators
List the names of common central alpha 2 agonists
Clonidine
Guanabenz
Guanfacine
What is Nesiritide and how does it act?
It is a vasodilator that BINDS NATRIURETIC FACTOR RECEPTORS
What illicit drug increases the risk of malignant hyperthermia with volatile anesthetics and succinylcholine?
MDMA “Ectasy-Molly”
What is the half-life of cocaine?
23.6 min
What is the treatment for patients exposed to organophosphates?
Leads to an anticholinergic crisis treated with Pralidoxime
What are the signs and symptoms of a cholinergic crisis?
Similar to a myasthenic crisis
Diarrhea Sweating Lacrimation Miosis Bradycardia Hypotension
What are the major side effects of beta blockers?
Hypoglycemia
Hyperkalemia
Bronchospasm
What is the treatment for acute dystonia that may arise as a side effect of metoclopromide?
IV Benztropine, an anticholinergic, is effective for most dystonic reactions with 5 minutes
What factors increase the rate of rise of FA?
1) Anesthetic concentration (FD); a higher FD leads to an higher FI, which increases the rate of rise of FA
2) Alveolar ventilation (VA); hyperventilation increases rate of rise of FA
3) Characteristics of the breathing circuit; high gas inflow from anesthesia machine speeds rise of FI
Which volatile anesthetic is the MOST soluble?
1) Methoxyflurane
Halothane is the second most soluble volatile anesthetic
What volatile anesthetic is the LEAST soluble? why?
Nitrous oxide is the LEAST soluble volatile anesthetic over Desflurane (2nd most) although Nitrous oxide has a higher blood gas solubility because of the high concentrations of nitrous oxide used
Xenon is actually the least
How does hyperventilation vs. hypoventilation effect the FI/FA ratio?
HYPERVENTILATION delivers more anesthetic to lungs INCREASING the rate of rise of FA/FI
HYPOVENTILATION thus DECREASES the rate of rise of FA/FI
How does cardiac output effect the FI/FA ratio?
As CO increases, the uptake increases, thus DECREASING the rise of alveolar partial pressure and slowing inhalational induction
How does a left to right cardiac shunt effect the FI/FA ratio vs. a right to left cardiac shunt?
Left to right: NO CHANGE in FA and NO change in induction
Right to left: DECREASED rise of arterial concentration of anesthetic and slower induction
How does FRC effect the FI/FA ratio?
An INCREASE in FRC yield more air space with a dilution of anesthetic and, therefore, DECREASES the rate of rise
A DECREASE in FRC (in pregnant patients) thus INCREASES the rate of rise
What enzyme in steroid synthesis is inhibited by Etomidate?
11 beta OH hydroxylase
What effect do barbiturates have on the brain?
- Vasoconstriction leads to decreased CBF
- CPP increases since the drop in ICP exceeds the decline in MAP (CPP = MAP - ICP)
- May protect the brain from FOCAL ISCHEMIA but probably not from GLOBAL ISCHEMIA
What does Ketamine dissociate?
It functionally “dissociates” the thalamus from the limbic system
MOA of Ketamine
NMDA receptor antagonism
also inhibits the reuptake of norepinephrine leading to its sympathomimetic effect
Describe Morphine’s lipid solubility
It has a very LOW lipid solubility and is known to be more hydrophilic
What opioid may depress cardiac contractility?
Meperidine (Demerol)
What subunit of the Na+ channel receptor local anesthetics bind to?
The alpha subunit
What affects nerve fiber sensitivity to local anesthetics?
The axonal diameter and myelination
- spinal nerves sensitivity is autonomic > sensory > motor
What is the key determinant of local anesthetic POTENCY?
Lipid Solubility