Reading...
Play button
Play button
Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
37 Cards in this Set
- Front
- Back
|
A drug is given at a dose of 50 mg/kg to a 70 kg man. The plasma concentration after giving it is 10 mg/ml. The elimination half-life is 8 hours. Clearance would be:
A. 1.3 l/h B. 3 l/hr C. 0.03 l/hr D. 125 l/hr |
Answer should be 30 ml/hour
Elimination Half life = .693Vd/Cl Cl = .693Vd/half life Cl = .693 * 350 / 8 Cl = 30 ml/hour |
|
|
A drug is given orally and 95% absorbed. Only 25% reaches the general circulation due to hepatic first pass metabolism. If hepatic blood flow is 1500 mls/min, the hepatic clearance is:
A. 400 ml/min B. 900ml/min C. 1100 ml/min D. 1425 ml/min |
C.Correct ((0.95-0.25)/0.95 = 1st pass metabolism * hepatic flow rate = 1105 ml/min)
|
|
|
Rectal administration of drugs:
A. Gives predictable blood levels B. From lower 1/3 avoids first pass and from upper 2/3 does not C. None undergoes 1st pass metabolism D. All of it undergoes 1st pass metabolism |
ANSWER B. From lower 1/3 avoids first pass and from upper 2/3 does not
|
|
|
GP05 [Mar99] [Jul00] [Apr01] [Jul04] LD50 is:
A. Median lethal dose B. Determined in phase I clinical trial C. Determined from log-dose response curve D: Dose causing death in 50% of animals within 4 hours E. Half the mean lethal dose. F. Best expressed as ratio of lethal dose in 50% of animals to effective dose in 50% |
A. Median Lethal Dose
|
|
|
Which of the following crosses the blood-brain barrier?
A. GABA B. Propranalol C. Suxamethonium D. Edrophonium E. Dopamine |
B. Propranalol - Yes, side effects include somnolence and depression
|
|
|
With regard to drug receptor binding:
A. A competitive antagonist has no intrinsic activity B. A partial agonist has less receptor affinity than a full agonist C. KD is maximal intrinsic efficacy D. Elimination rate constant is defined by the clearance E. Half life depends on rate of drug absorption E. |
A. A competitive antagonist should have no intrinsic efficacy
|
|
|
A partial agonist:
A. Always antagonises a full agonist B. Can never be used to antagonise a full agonist C. Has a dose response curve similar to a full agonist in the presence of a non-competitive antagonist |
C. Yes, this is correct (or more correctly – in the presence of a competitive irreversible antagonist… )
|
|
|
Placental transfer of drugs:
A. Increases in late pregnancy B. Increases late because of decreased albumin C. Do not cross because > 600 daltons D. Lipid soluble drus diffuse across according to concentration gradient E. Increased diffusion if greater plasma protein binding in foetus |
A. Probably most correct, rapidly growing fetus = more nutrient demands
B. ??? C. partially true : uptodate : unionised/lipid soluable freely cross placenta if MW<600daltons D. True... Fick's Law E. True... if there is high protein binding in fetus then there will be a greater concentration difference, therefore increasing diffusion |
|
|
Regarding Pharmacokinetics:
A.systemic clearance is related to the bioavailabilty and half life B. Half life is inversely proportionate to clearance C. Half life is proportional to steady state D. Elimination is expressed as clearance speed of a given volume of blood from a substance E. Conjugation involves hydrolysis |
B. True
|
|
|
An ether bond is:
A. Formed from condensation of 2 alcohols B. Hydroxyl group on middle bond |
A. Correct. 2 ethanols -> Diethyl ether + H2O
|
|
|
GP11 [Feb00] [Mar03] The NMDA receptor
A. Ketamine is an agonist B. Requires glycine as a modulating protein (“YES PROTEIN ! ”) to have its effect C. Mg+2 blocks the receptor D. Is not permeable to Calcium |
ANSWER C
* Ketamine is an ANTAGONIST * Glycine is an AMINO ACID (not a protein) - several persons submitting this question noted the "protein" wording) * Mg+2 normally blocks the ion channel in the molecule * When open, it is permeable to Na+, K+ and Ca+2 But Glycine is required as a co agonist to activate NMDA |
|
|
GP12 [Feb00] [Jul02] Activated charcoal:
A. Should be given with sorbitol B. Is not effective against theophylline C. Should be given with ipecac D. Should be given in a drug:charcoal ratio of 1:10 |
ANSWER D
Core recommendations are summarized as follows: Indications : carbamazepine, dapsone, phenobarbital, quinine, or theophylline. Relative indication : amitriptyline, dextropropoxyphene, digoxin, digitoxin, disopyramide, nadolol, phenylbutazone, phenytoin, piroxicam, and sotalol. No evidence for giving cathartics such as sorbitol Ipecac used to induce vomiting, therefore will reduce AC effect and aspiration risk. Contraindications -unprotected airway -intestinal obstruction -gastrointestinal tract that is not intact -decreased peristalsis. Potential complications include transient constipation (especially in nonambulatory patients), bowel obstruction, regurgitation, and aspiration, with consequent pulmonary complications (including death) if the nasogastric tube is incorrectly placed. |
|
|
GP13 [Apr01] [Jul04] Therapeutic index:
A. Easy to determine in humans B. drugs that undergo zero order kinetics have multiple therapeutic indices C. low TI has a high margin of safety D. measures the desired effects of a drug E. Derived from LD50/ED50 |
ANSWER E
TI = TD50/ED50 or LD50/ED50 TI is difficult to establish in human due to ethical considerations |
|
|
GP14 [Apr01] [Jul04] (A Basic drug with a pKa of 8.7)
A. Some will be ionised at plasma ph B. Will be predominately unionised at plasma pH C. Will be predominantly ionised at plasma pH |
ANSWER C
|
|
|
GP15 [Apr01] [Jul02] [Mar03] Oxygen toxicity
A. Causes convulsions at less than 100 kPa B. Causes lipid peroxidation at less than 100 kPa C. Causes chest pain at less than 100kPA D. Causes retinopathy of prematurity greater than 100kPa |
ANSWER B
A is incorrect. CNS toxicity occurs at > 200 kPa B. correct In general, "hazards" associated with oxygen use include 1. hypoventilation, i.e. in pts with COPD who are chronic CO2 retainers 2. Absorption Atelectasis ( alveolar collapse)- high oxygen concentrations can cause atelectasis in areas of low ventilation relative to perfusion. VC can be decreased by 500-800ml as a consequence 3. Retinopathy of prematurity ( previously called retrolental fibroplasia) - FIO2 > 0.50 to neonates can encourage "disorganized vascular proliferation and fibrosis".. which can make the retina opaque, ." as well as retinal detachment" 4. Bronchopulmonary dypasia - in neonates 5. Fire hazard |
|
|
GP16 [Jul01] With regard to log dose - response curves:
A. The response is fairly linear over the 20-80% range. B. The Dose is fairly linear over the 20-80% range C. The ED50 and slope are characteristic for each drug D. ? E. ? |
ANSWER A
between 20-80% response to log dose is fairly linear |
|
|
GP18 [Jul01] With regards to diffusion through a membrane:
A. Directly proportional to thickness B. Inversely proportional to thickness C. Inversely proportional to Surface area D. Inversely proportional to concentration difference E. ? |
ANSWER B
Fick's law |
|
|
GP19 [Mar02] [Mar03] Which of following act via ligand gated channel?
A. Dexamethasone B. Heparin C. Morphine D. Vecuronium E. ? |
ANSWER D
mu recptors are G protein (Gq) nicotinic ACh receptors are Na channel |
|
|
GP20 [Jul02] Zero order kinetics means:
A. Clearance is proportional to dose B. T1/2 = Clearance C. Drug is eliminated at a constant rate regardless of dose. D. Elimination half time will vary according to dose. E. ? |
ANSWER C
|
|
|
GP21 [Feb04] All exist as Racemic mixtures except:
A. Thiopentone B. Lignocaine C. Bupivucaine D. Isoflurane E. Enflurane |
ANSWER B
|
|
|
GP23 [Feb04] Chemoreceptor trigger zone
A. Contains 5HT3 and D2 receptors B. Not involved in inner ear mediated nausea C. Located in the pons D. Electrical stimulation of these centers does induces vomiting E. Responsible for coordinating vomition. |
ANSWER A
Pneumonic Sally Hates Men On drugs Serotonin 5HT3 Histamine H1 Muscaric M1 Opiods mu Dopamine D2 B. False C. False, located in area postrema in the medulla under the 4th ventricle D.False, Electrical stimulation of these centers does not induce vomiting but application of emetic drugs does - if and only if the vomition centers are intact E. False, controlled by vomiting centre in the medulla which receives inputs from CTZ, vestibular stem, CN X, high centres in the CNS |
|
|
GP24 [Feb04] [Jul04] Glutamate
A. Dissociates slowly from the NMDA receptor B. Does not act at AMPA and kainite receptors C. Inhibitory neurotransmitter in CNS D. Easily crosses the BBB to have central effects E. Is metabolised to GABA |
ANSWER A
A - correct B - incorrect has actions at NMDA, kainate and AMPA receptors C - incorrect; glutamate is an excitatory neurotransmitter D- incorrect; Glutamate does not easily pass the blood brain barrier, but, instead, is transported by a high-affinity transport system E- incorrect; Glutamate also serves as the precursor for the synthesis of the inhibitory GABA in GABA-ergic neurons |
|
|
GP25 [Feb04] Regarding pharmacokinetics in pregnancy:
A. paracetamol uptake increased B. increased sensitivity and faster onset with thiopentone C. hepatic clearance decreased by decreased protein binding |
ANSWER B
A. False - Delayed gastric emptying = delayed absorption B. True - Increased cardiac output increases speed of onset C. False - Decreased PPB = Increased free drug available for hepatic extraction |
|
|
GP26 [Jul04] Which is an antagonist at the NMDA receptor?
A. Dexamethasone B. Dextropropoxyphene C. Dexmedetomidine D. Dextromethorphan E. Dexmethamphetamine |
Answer is D
- "Although dextromethorphan is known to function as an NMDA-receptor antagonist, the dextromethorphan-binding sites are not limited to the known distribution of NMDA receptors (Elliott et al., 1994)." from Goodman and Gilman Dextromethorphan, marketed primarily as an antitussive, is an antagonist of the glutamatergic NMDA receptor (Ref:Wikipedia ) A - synthetic glucocorticold steriod B - Dextropropoxyphene napsylate is a centrally acting, synthetic opioid analgesic structurally related to methadone (MIMS) C - full alpha 2 agonist E - Sympathomimetic |
|
|
GP27 [Jul04] Comparing dexamethasone and hydrocortisone:
A. Both are endogenous hormones B. Dexamethasone has 8x potency of hydrocortisone C. Both have mineralocorticoid activity D. Dexamethasone is the only water-soluble compound |
A. False
Dexamethasone is synthetic Hydrocortisone is endogenous B. False 25x potent C. False Hydrocortisone gluco to cortio activity is 1 :1 Dex is 1:0 D. False Dexamethasone comes in tablet and IV formulations Hydrocortisone can be dissolved in water |
|
|
GP28 A drug has hepatic extraction ratio of 0.7 and is 30% abosorbed, what is the bioavailability
A. 0.3 B. 0.7 C. 0.21 D. 0.09 E. 0.03 |
ANSWER D
Bioavailability = (1 - ER) x fraction absorbed =(1-0.7)*0.3 =0.09 |
|
|
GP29 Which of the following drugs cannot cross the BBB?
A. Ondansetron B. Scopolamine C. Metoclopramide D. Droperidol E. Domperidone |
ANSWER E
|
|
|
GP29 Which of the following drugs cannot cross the BBB?
A. Ondansetron B. Scopolamine C. Metoclopramide D. Droperidol E. Domperidone |
ANSWER E
All except domperidone therefore it is useful for treating nausea in patients with parkinson's disease |
|
|
GP30 (Mar10 version)
Which is true for LD50? A. a probit score of 5 means it is 5 SD away from the median B. mean lethal dose C. calculated from graded dose-response curves D. calculated from quantal dose-response curves E. you keep giving a bunch of animals a drug until the animals die |
ANSWER D
|
|
|
GP31 Which is not a ligand gated channel?.
A. Alpha-2 Receptor B. 5HT3 Receptor C. Nicotinic cholinergic receptor D. GABA receptor E. NMDA receptor |
ANSWER A
A. Alpha-2 Receptor - receptors linked to G protiens A is correct B. 5HT3 Receptor - is ligand gated C. Nicotinic cholinergic receptor - is ligand gated D. GABA receptor - ligand gated E. NMDA receptor - is ligand gated |
|
|
Haloperidol is more potent than chlorpromazine. Potency of a therapeutic formultation refers to
A. Strength of binding to receptors B. Duration of action of receptors C. Size of the dose required to produce an effect D. Elimination half life of a drug E. Proportion of available receptors occupied by a drug |
ANSWER C
|
|
|
Absorption of orally administered drugs is affected by which of the following
A. Intestinal transit B. Co-administered drugs C. P. glycoprotein D. Presence of food E. All of the above |
ANSWER E
|
|
|
Which of the following conidtions predisposes to higher rate of transport through the blood-brain barrier?
A. Presence of ionized drug molecules B. Presence of protein-bound drugs molecules D. Presence of water-soluble drugs molecules D. Presence of inflamed meninges E. All of the above |
ANSWER D
The ability of a drug to the pass the BBB depends on 1. Integrity of the BBB 2. Molecular size 3. Lipid solubility 4. Ionic status 5. Concentration gradient (related to both dose and protein binding) 6. Specific transport mechanisms (L-dopa and valproate) |
|
|
Which one of the following has partial agonistic activity as a major therapeutic mechanism
A. Propranaol B. Olanzepine C. Lithium D. Pindolol E. Carbamazepine |
ANSWER D
|
|
|
Mechanisms of transmembrane signaling are the following EXCEPT:
A. Transmembrane receptors that bind and stimulate a protein tyrosine kinase B. Gene replacement by the introduction of a therapeutic gene to correct a genetic effect C. Ligand-gated ion channels that can be induced to open or close by binding a ligand D. Transmembrane receptor protein that stimulates a GTP-binding signal transducer protein (G-protein) which in turngenerates an intracellular second messenger |
ANSWER B
|
|
|
substance which changes the activity of an effector element but doesn’t belong to second messengers:
A. cAMP B. cGMP C. G–protein D. Calcium ion |
ANSWER C
|
|
|
The increase of second messengers’ (cAMP, cGMP, Ca
2+ etc.) concentration leads to: A. Inhibition of intracellular protein kinases and protein phosphorylation B. Proteinkinases activation and protein phosphorylation C. Blocking of interaction between a receptor and an effector D. Antagonism with endogenous ligands |
ANSWER B
|
