Correct Answer c chlorothiazide D



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A 1 mg

  • B 10 mg Your Answer

  • C 100 mg Correct Answer

  • D 1000 mg

    Explanation

    1%=1000mg in a 100ml solution is the a starting point.

    Therefore 1ml=10mg. 

    Therefore 2ml=20mg

    Therefore 10ml=100mg

    Question 207

    Regarding efficacy, which of the follwing statements is correct?


    Your answer was correct

    • A It can be measured with a quantal dose response curve

    • B Partial agonists have higher maximal efficacy than full agonists

    • C It is the maximum effect a drug can bring about regardless of dose Correct Answer

    • D It is the drugs ability to produce 50% of its maximal effect

    Explanation

    Efficacy is measured by a graded dose response curve and not a quantal dose response curve. By definition partial agonists have a lower efficacy than full agonists

    Question 208

    Regarding t1/2, which of the following statements is true?
    Your answer was not correct


    • A It can be poor predictor of clearance Correct Answer

    • B Is not affected by age

    • C Is not related to Vd

    • D Is related to volume of distribution and protein binding Your Answer

    Explanation

    T1/2 = 0.7 x VD/CL. There is a relation to the Vd. Disease states can affect T1/2. Renal impairment, which occurs in 2/3 of the elderly, will lengthen the half-life of most drugs. There is no relation to protein binding

    Question 209

    Which of the following is an example of a phase II biotransformation?
    Your answer was not correct


    • A Oxidation Your Answer

    • B Reduction

    • C Methylation Correct Answer

    • D Hydrolysis

    Explanation

    Phase one reactions are hydration, oxidation and reduction. Phase two reactions are glucuronidation, acetylation, glutathione conjugation, glycine conjugation, sulfate conjugation, methylation, and water conjugation

    Question 210

    With regard to properties of a drug, which of the following statements is correct?
    Your answer was correct


    • A Efficacy is the maximum response produced by a drug Correct Answer

    • B Spare receptors are present if Kd 50 is the same as EC 50.

    • C Potency is the same as affinity.

    • D TD50 is the concentration of a drug necessary to produce toxic effects 50 % of the time

    Explanation

     

    Spare receptors are present if the EC50

    Potency: how much of a drug that is required to produce an effect.

    Affinity: how tight the drug binds to its receptors.

    TD50 is the dose required to produce toxic effects in 50% of patients.

    Question 211

    Which of the following statements regarding Naloxone is false?
    Your answer was not correct


    • A Intravenous administration reverses opioid effects in 1-2min

    • B Naloxone has equal affinity for mu, kappa and delta receptors Correct Answer

    • C Naloxone is a pure antagonist

    • D Tolerance to naloxone does not develop Your Answer

    Explanation

    Naloxone is a pure antagonist. It has a very high affinity for mu receptors and a lower affinity for the other receptor binding sites.  Naloxone has a half life of 1-2 hours when given by injection and 10 hours when taking via the oral route.  Although naloxone is well absorbed via the oral route it undergoes rapid first pass metabolism. IVI administration reverses opioid toxicity in 1-3 minutes. There is no tolerance to the antagonistic action of these agnets, nor does withdrawal of naloxone after chronic administration precipitate an abstinence syndrome

    Question 212

    Which of the following is an example of Type 1 biotransformation reactions?
    Your answer was not correct


    • A Methylation Your Answer

    • B Acetylation

    • C Hydrolysis Correct Answer

    • D Glucuronidation

    Explanation

     

    Phase one reactions are hydration, oxidation and reduction. Phase two reactions are glucuronidation, acetylation, glutathione conjugation, glycine conjugation, sulfate conjugation, methylation, and water conjugation



    Question 213

    Which of the following statements regarding the bioavailability of a drug is correct?


    Your answer was correct

    • A Must be 100% if given by inhalation.

    • B Is high if the drug is hydrophilic.

    • C Is equal to 1 (the extraction ratio)

    • D Is 70% for orally administered Digoxin. Correct Answer

    Explanation

     

    Inhalation gives a bioavailability of 5 to <100%. Hydrophilic and lipophilic drugs can have low rates of bioavailability. Too lipophilic, the drug will not be soluble enough to cross the water layer adjacent to the cell. The bioavailability of the drug (F) can be predicted from the extent of absorption (f) and the extraction ration (ER). F=f x (1-ER). 10% bioavailability is only via intravenous administration



    Question 214

    What is the half life of Lignocaine?


    Your answer was not correct

    • A 10 minutes

    • B 30 minutes Your Answer

    • C 60 minutes

    • D 120 minutes Correct Answer

    Explanation

    Lignocaine has a t1/2 of 1-2 hours

    Question 215

    Calculate the half life of Digoxin in a 70 kg patient with a renal clearance of 8.4L/min and volume distribution of 5 L/Kg
    Your answer was not correct


    • A 14 hours

    • B 29 hours Correct Answer

    • C 36 hours Your Answer

    • D 44 hours

    Explanation

     

    T1/2 = 0.7 x (VD/CL)



    0.7 x ((5x70)/8.4) = 29hrs

    Question 216

    Which of the following statements is correct?

    The volume of distribution...


    Your answer was not correct

    • A Is proportional to half life. Correct Answer

    • B Is calculated by dividing the amount of drug by it's clearance

    • C If high suggests homogeneous distribution throughout tissues Your Answer

    • D If low suggests homogeneous distribution throughout tissues

    Explanation

     Vd is an apparent volume.

    The volume of distribution= amount of drug in the body/ concentration of the drug in blood or plasma.

    Drugs with a high VD have higher extravascular concentrations than intravascular and are not homogenously distributed.

    T1/2 = 0.7 x (VD / CL)

    Question 217

    How many mg in 2ml of a 0.5% weight per volume solution?


    Your answer was correct

    • A 10mg Correct Answer

    • B 1 mg

    • C 100mg

    • D 5mg

    Explanation

     

    1%=1000mg in a 100ml solution is the a starting point.



    0.5%=500mg in 100ml solution.

    Therefore 1ml=5mg. 

    Therefore 2ml=10mg

    Question 218

    Which of the following is an example of a phase I reaction?
    Your answer was correct


    • A Sulphation

    • B Glucuronidation

    • C Hydration Correct Answer

    • D Acetylation

    Explanation

    Phase one reactions are hydration, oxidation and reduction.

    Phase two reactions are glucuronidation, acetylation, glutathione conjugation, glycine conjugation, sulfate conjugation, methylation, and water conjugation

    Question 219

    Calculate a Phenytoin loading dose for a 70 kg male; Target concentration 10 mg/L, Vd 0.5 L/kg


    Your answer was correct

    • A 350 mg Correct Answer

    • B 300 mg

    • C 400 mg

    • D 3500 mg

    Explanation

     

    The LD = VD (l/kg) x TC. Therefore 0.5 x 70 =35L.



    35 x 10=350mg

    Question 220

    Regarding irreversible antagonists, which of the following statements is correct?
    Your answer was correct


    • A Require regeneration of receptors for further agonist action Correct Answer

    • B Can be displaced by increasing concentration of agonist

    • C Can be displaced by increasing potency of agonist

    • D Can be displaced by increasing efficacy of agonist

    Explanation

    Competitive antagonists can be overcome by sufficiently high concentration of agonists. Irreversible antagonists cannot. Consequently, the duration of action of such an irreversible antagonists relatively independent of its own rate of elimination and more dependent upon the rate of turnover of receptor molecules

    Question 221

    Which of the following drugs has a half-life of 6 hours?
    Your answer was correct


    • A Diazepam

    • B Aspirin

    • C Digoxin

    • D Atenolol Correct Answer

    Explanation

    Aspirin's half life in 3-5hrs (first order kinetics) and 15hrs (zero order kinetics).

    Digoxin’s half life is 40 hrs

    Diazepam’s is 20-40hrs

    Question 222

    Which volatile anaesthetic is the least metabolized?
    Your answer was correct


    • A Desflurane Correct Answer

    • B Sevoflurane

    • C Halothane

    • D Isoflurane

    Explanation

    The extent of hepatic metabolism, the order (most to least) of inhaled anaesthetic are methoxyflurane, halothane, enflurane, sevoflurane, isoflurane, desflurane, nitrous oxide. Nitrous oxide undergoes zero metabolism.

    Question 223

    Which of the following is an amide local anaesthetic agent?

     

     



     
    Your answer was not correct

    • A Benzocaine Your Answer

    • B Tetracaine

    • C Cocaine

    • D Prilocaine Correct Answer

    Explanation

    All the rest are Ester type local anaesthetics. Examples of Amide local anaesthetics are: lignociane, mepivacaine, bupivacaine, etidocaine and ropivacaine

    Question 224

    In pseudo (plasma) cholinesterase deficiency which of these two drugs will have a prolonged effect?

     

     



     
    Your answer was not correct

    • A Succinylcholine and Esmolol Your Answer

    • B Remifentanil and Esmolol

    • C Succinylcholine and Procaine Correct Answer

    • D Mivacurium and Esmolol

    Explanation

    Pseudocholinesterase deficiency will result in a prolonged effect of the following: succinylcholine, mivacurium, procaine, and cocaine. Iatrogenic causes of lower plasma pseudocholinesterase activity include medications such as the following:


    • Anticholinesterase inhibitors

    • Bambuterol

    • Chlorpromazine

    • Contraceptives

    • Cyclophosphamide

    • Echothiophate eye drops

    • Esmolol

    • Glucocorticoids

    • Hexafluorenium

    • Metoclopramide

    • Monoamine oxidase inhibitors

    • Pancuronium

    • Phenelzine

    Tetrahydroaminacrine

    Question 225

    Prolonged duration of neuromuscular blockade is seen following a vecuronium infusion.  Which of the following is the possible cause?

     

     



     
    Your answer was not correct

    Explanation

    In rare cases, long-term use of neuromuscular blocking drugs to fascilitate mechanical ventilation in ICU settings may be associated with prolonged paralysis and/or skeletal muscle weakness.  Patients may have received other drugs such as broad spectrum antibiotics, narcotics and steroids and may have severe diseases which lead to electrolyte imbalances, hypoxic episodes of varying duration, acid-base imbalance, hyperthermia and extreme debilitation any of which may enhance the actions of a neuromuscular blocking agent. 

    Hypothermia (25 to 28°C) has been associated with a decreased requirement for nondepolarizing neuromuscular blocking agents.

    Question 226

    Which of these drugs can be used to treat central anticholinergic syndrome?

     
    Your answer was not correct


    • A Physostigmine Correct Answer

    • B Benztropine Your Answer

    • C Pyridostigmine

    • D Atropine

    Explanation

    Physositgmine is the only carbamate that is well absorbed form all sites (lungs, skin, eye, gut) and is distributed into the central nervous system. 

    Question 227

    Which of the following opioids have INACTIVE metabolites? 

     
    Your answer was not correct



    • A Oxycodone Your Answer

    • B Morphine

    • C Methadone Correct Answer

    • D Codeine

    Explanation

    Morphine=hydromorphone.

    Codeine= hydrocodone.

    Oxycodone= oxymorphone.

    Pethidine = norpethidine

    Unlike codeine, morphine, hydromorphone, pethidine or oxycodone, methadone has no active metabolites and is therefore a good choice for patients at risk for toxicity from metabolite accumulation

    Question 228

    With the MAOI tranylcypromine, which drug will be least problematic?

     

     



     
    Your answer was not correct

    • A Propofol Correct Answer

    • B Pethidine

    • C Ephedrine Your Answer

    • D Phenylephrine

    Explanation

    Tranylcypromine is a MAOI, which will inhibit the catabolism of dietary amines. When foods containing tyramine are ingested, the patient may develop a hypertensive crisis. The mechanism is poorly understood but is thought that tyramine displaces noradrenaline from the storage vesicles. Therefore all drugs with sympathommimetic properties will be problematic when associated with MAOIs. Pethidine is associated with serotonin syndrome when given with the MAOI drug group

    Question 229

    Which drug does NOT have antiemetic properties when used as an?

     

     



     
    Your answer was correct

    • A Ketamine Correct Answer

    • B Ondansetron

    • C Midazolam

    • D Dexamethasone

    Explanation

    Ketamine does not have antiemetic properties but is often used with propofol=Ketofol, as Propofol has antiemetic effects. The antiemetic effect is stated in Katzung, but there is some controversy as to whether it really does. See below.

    In a study reported in the clinical journal of anaesthetics it stated that many anaesthesiologists used propofol for its antiemetic effect. There is strong evidence for its antiemetic efficacy after anaesthesia maintained by a propofol infusion and also for its use in the post anaesthetic patient. However, there is little evidence to support its use purely at induction of anaesthesia or using it at the beginning or end of a case in an attempt to reduce postoperative nausea and vomiting. This is especially true in cases lasting longer than a few minutes

    Question 230

    Which of the following inhaled gases are metabolised greater than 10%?

     

     
    Your answer was not correct



    • A Isoflurane Your Answer

    • B Sevoflurane

    • C Halothane Correct Answer

    • D Nitrous oxide

    Explanation

    Metabolism of inhaled anaesthetics:

    Nitrous oxide 0%.

    Sevoflurane 2-5%.

    Isoflurane- <2%.

    Halothane >40%.

    Enflurane-8%. 

    Question 231

    Which of the following is most likely to cause raised intracranial pressure?

       

     

     


    Your answer was correct

    • A Ketamine Correct Answer

    • B Propofol

    • C Thiopentone

    • D Nitrous oxide

    Explanation

    Ketamine markedly increases cerebral blood flow, cerebral oxygen consumption and intracranial pressure. Inhaled anaesthetics decrease the metabolic rate of the brain but do increase cerebral blood flow. Nitrous oxide increases cerebral blood flow the least. Thiopentone decreases cerebral metabolism, oxygen consumption and cerebral blood flow. Propofol reduces cerebral blood flow and cerebral metabolism

    Question 232

    The following cause an increase in intra-abdominal pressure?

     

     


    Your answer was not correct

    • A Neostigmine

    • B Suxamethonium Correct Answer

    • C Morphine

    • D Metoclopramide Your Answer

    Explanation

    In some patients especially muscular ones, the fasiculations associated with suxamethonium will cause a rise in intra gastric pressure from 5-40cmH20. The result of which may cause vomiting and aspiration. This effect is not seen with the non depolarising muscle relaxants

    Question 233

    The following increase intra-ocular pressure?
    Your answer was not correct


    • A Hypoventilation

    • B Ketamine

    • C Suxamethonium Correct Answer

    • D Halothane Your Answer

    Explanation

    Intraocular pressure increases following administration of suxamethonium. It occurs 1 min after injection, is maximal at 2-4 min and starts to subside after 5min. The mechanism may involve contractions of tonic myofibrils or transient dilation of chorodial blood vessels. Despite this increase, the use of suxamethonium is not contraindicated unless the anterior chamber is to be opened.

    Question 234

    Thiopentone is a “short-lasting” barbiturate because?

     

     



     
    Your answer was correct

    • A It is administrated by IV injection

    • B It is bound to the “sleep centre” in the brain

    • C It is rapidly distributed throughout the body Correct Answer

    • D It is metabolised rapidly by brain and liver

    Explanation

    It is “short lasting” because of the rapid removal form brain tissue into the other highly vascularised tissues and is redistributed to muscle, fat and eventually all body tissues. It is only metabolised at a rate of 12-16% following a single dose. It facilitates the action of GABA and increase the opening of the Cl channels.

    Question 235

    Which of the following may be administered via the tracheal mucosa?

     

     


    Your answer was not correct

    • A Calcium chloride

    • B Suxamethonium

    • C Lignocaine Correct Answer

    • D Theophylline Your Answer

    Explanation



    Resuscitation drugs such as  lignocaine, epinephrine, atropine, naloxone, and vasopressin  are absorbed via the trachea. Administration of resuscitation drugs into the trachea, however, results in lower blood concentrations than the same dose given intravascularly.

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