Exam 2006 (B) - PHA5515 April 29, 2006 Exam Form B Total:...

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PHA5515 April 29, 2006 Exam Form B Total: 122 points Read each question carefully before answering. Answer only the question that is written on the page; don't add any of your own parts to it. Remember the Academic Dishonesty Policy; keep your eyes on your own paper. Please turn in the test and answer sheets when you have finished. Good Luck!
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True/False (2 pt) Sumatriptan (Imitrex®) and zolmitriptan (Zomig®) are some commonly used antimigraine drugs (Figure 1). Methysergide, ergotamine (Ergomax®) and LSD can have some antimigraine effects but may have side effects including hallucinations (Figure 2). You suspect that these efficacies are based on the ability of these drugs to bind to different subtypes of serotonin receptors. Therefore you compare the efficacies and potencies of these drugs to displace the specific binding of 3 H-serotonin from its receptors in homogenized brain samples (Figure 3). Zomig® can only bind to one third of the sites occupied by 3 H-serotonin (the 5HT1 receptor subtype) while LSD can only bind to the other two thirds of the receptors (the 5HT2 receptor subtype). Which of the following conclusions would be true? 1. Ergomax® would be able to compete for at least a portion of specific binding if a competition curve were performed using 3 H-Zomig® as the radiolabeled drug. 2. Imitrex® would be able to compete for at least a portion of specific binding if a competition curve were performed using 3 H- LSD as the radiolabeled drug. 3. Methysergide and Ergomax® can bind to both 5HT1 and 5HT2 receptor subtype but the IC 5 o values for the two subtypes are more alike for Ergomax® than they are for methysergide. 4. Imitrex® can not bind specifically to any 5HT receptor subtype at nanomolar concentrations. 5. Ergomax® clearly has a lower affinity for the 5HT1 receptor subtype compared to Zomig®'s affinity for the 5HT1 receptor subtype. 6. Methysergide clearly has a lower affinity for the 5HT1 receptor subtype compared to its affinity for the 5HT2 receptor subtype. 7. You would suspect that 34% of the serotonin receptors j) are involved in the antimigraine effects of these drugs. 8. You would suspect that 66% of the serotonin receptors (-1 i) are involved in the hallucinogenic effects of these drugs. 9. Imitrex® is an antagonist at the 5HT2 receptor subtype. 10. Methysergide is a partial agonist at the 5HT1 receptor subtype. 11. Methysergide is a partial agonist at the 5HT2 receptor subtype.
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The following questions refer to the dose-response curves below. Choose the best correct answer (2 pts each; answers may be used repeatedly). A. less efficacious B. more efficacious C. less potent D. more potent E. Both A and C F. Both A and D G. Both B and D H. a competitive antagonist I. a noncompetitive antagonist. J. None of the above
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Exam 2006 (B) - PHA5515 April 29, 2006 Exam Form B Total:...

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