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Pharmacology MCQs (Part- 13) with answers

PHARMACOLOGY

1. Twenty months after finishing her chemotherapy, the woman had a relapse of breast cancer. The cancer was now unresponsive to standard doses of chemotherapy. The decision was made to treat the patient with high-dose chemotherapy followed by autologous stem cell transplantation. Which of the following drugs is most likely to be used to mobilize the peripheral blood stem cells for the patient’s autologous stem cell transplantation?
(a) Erythropoietin
(b) G – CSF
(c) Interleukin – 11
(d) Intrinsic factor

2. The combination of trimethoprim and sulfamethoxazole is effective against which one of the following opportunistic infections in the AIDS patient?
(a) Disseminated herpes simplex
(b) Cryptococcal meningitis
(c) Toxoplasmosis
(d) Oral cnadidiasis

3. The top four most commonly diagnosed cancers include all of the following except
(a) Lung
(b) Prostate
(c) Colon and rectum
(d) Thyroid

4. A 31-year-old man has gonorrhoea. He has no drug allergies, but he recalls that a few years ago while in Africa he had acute hemolysis following use of an antimalarial drug. The physician is concerned that the patient has an accompanying urethritis due to C trachomatis, though no cultures or enzyme tests have been performed. Which of the following drugs is most likely to be effective against gonococci and to eradicate C trachomatis in this patient?
(a) Cefixime
(b) Ciprofloxacin
(c) Ofloxacin
(d) Spectinomycin

5. The mechanism by which sulfasalazine exerts its primary action in ulcerative colitis is inhibition of
(a) Folic acid synthesis
(b) The formation of leukotrienes and prostaglandins
(c) Phospholipase C
(d) Proton pump activity

6. Which one of the following adverse effects is most likely to occur with sulfonamides?
(a) Hematuria
(b) Fanconi’s aminoaciduria syndrome
(c) Kernicterus in the newborn
(d) Skin reaction

7. This drug is the preferred agent for teatment of nocardiosis and, in combination with pyrimethamine, is prophylactic against preumocystis carinii infections in AIDS patiens.
(a) Ampicillin
(b) Clindamycin
(c) Norfloxacin
(d) Sulfadiazine

8. Supplementary folinic acid may prevent anemia in folate-deficient persons who use this drug; it is a weak base, and achieves tissue levels similar to those in plasma
(a) Ciprofloxacin
(b) Norfloxacin
(c) Sulfacetamide
(d) Trimethoprim

9. It is now recommended that Trovafloxacin be reserved for treatment of life-threatening infections because
(a) Bacterial resistance to the drug is very common
(b) Complete liver failure has occured
(c) It is very expensive
(d) Its use is associated with torsade de pointes

10. The primary reason for the use of drug combinations in the treatment of tuberculosis is to
(a) Ensure patient compliance with the drug regimen
(b) Reduce the incidence of adverse effects
(c) Enhance activity against metabolically inactive mycobacteria
(d) Delay or prevent the emergence of resistance

11. The mechanism of high – level INH resistance of M tuberculosis is
(a) Formation of drug-inactivating N acetyltransferase
(b) Reduced expression of the katG gene
(c) Decreased intracellular accumulation of INH
(d) Mutation in the inhA gene

12. A patient with AIDS and a CD4 cell count of 100/μμμL has persistent fever and weight loss associated with invasive pulmonary disease that is due to M avium complex. Optimal management of this patient is to
(a) Treat with rifabutin, since it prevents the development of MAC bacteraemia
(b) Select an antibiotic regimen based on drug susceptibility of the cultured organism
(c) Start treatment with INH and pyrazinamide
(d) Treat the patient with clarithromycin, ethambutol, and rifabutin

13. This drug has been used prophylactically in contacts of children with infection due to Haemophilus influenzae type B. It is also prophylactic in meningococcal and staphylococcal carrier states. While the drug eliminates a majority of meningococci from carriers, highly resistant strains may be selected out during treatment
(a) Ciprofloxacin
(b) Clofazimine
(c) Dapsone
(d) Rifampin

14. Once–weekly administration of this antibiotic has prophylactic activity against bacteraemia due to M avium complex in AIDS patients.
(a) Azithromycin
(b) Clarithromycin
(c) Isoniazid
(d) Kanamycin

15. Which one of the following drugs is most likely to cause loss of equilibrium and auditory damage?
(a) Amikacin
(b) Ethambutol
(c) Isonazid
(d) Para-aminosalicylic acid

16. Chemical interactions between this drug and cell membrane components can result in the formation of pores lined by hydrophilic groups present in the drug molecule.
(a) Dactinomycin
(b) Griseofluvin
(c) Fluconazole
(d) Nystatin

17. Which one of the following statements about fluconazole is most accurate?
(a) It is highly effective in treatment of aspergillosis
(b) It does not penetrate the blood – brain barrier
(c) Its oral bioavailability is less than that of ketoconazole
(d) It inhibits demethylation of lanosterol

18. Which one of the following drugs is least likely to be effective in the treatment of esophageal candidiasis, it is used by the oral route?
(a) Amphotericin B
(b) Clotrimazole
(c) Fluconazole
(d) Griseofulvin

19. Which one of the following statements about flucytosine is accurate?
(a) It is bioactivated by fungal cytosine deaminase
(b) It does not cross the blood–brain barrier
(c) It inhibits cytochrome P450
(d) It is useful in esophageal candidiasis

20. Which one of the following drugs is most appropriate for oral use in vaginal candidiasis?
(a) Clotrimazole
(b) Griseofluvin
(c) Fluconazole
(d) Flucytosine

21. Which one of the following statements about the mechanisms of action of antiviral drugs is least accurate?
(a) The initial step in activation of famciclovir in HSV-infected cells is its phosphorylation by viral thymidine kinase
(b) The reverse transcriptase of HIV is 30–50 times more sensitive to inhibition by indinavir than host cell DNA polymerases
(c) Gancicolvir inhibits viral DNA polymerase but does not cause chain termination
(d) Increased activity of host cell phosphodiesterases that degrade tRNA is one of the antiviral actions of interferons

22. Which of the following drugs is most likely to cause additive anemia and neutropenia if administered to an AIDS patient taking zidovudine?
(a) Acyclovir
(b) Amantadine
(c) Ganciclovir
(d) Pentamidine

23. The antiviral actions of this drug include inhibition of both RNA and DNA synthesis. The drug is used for the treatment of severe respiratory syncytial virus infections in neonates.
(a) Amantadine
(b) Amprenavir
(c) Foscarnet
(d) Ribavirin

24. Regarding interferon alpha, which one of the following statements is least accurate?
(a) At the start of treatment, most patients experience flu-like symptoms
(b) Indications include treatment of genital warts
(c) It is used in the management of hepatitis C
(d) Lamivudine interferes with its activity against hepatitis B

25. Over 90% of this drug is excreted in the urine in intact form. Because its urinary solubility is low, patients should be well hydrated to prevent nephrotoxicity
(a) Acyclovir
(b) Amantadine
(c) Indinavir
(d) Zanamivir

26. Used in the prophylaxis and treatment of infection due to influenza viruses, this drug facilitates clumping of mature virions and their adhesion to infected cells.
(a) Amantadine
(b) Efavirenz
(c) Oseltamivir
(d) Rimantadine

27. Which statement regarding phase-specific chemotherapic agents is correct? They
(a) Are most effective in one phase of the cell cycle
(b) Effective in all phases of the cell cycle
(c) Are only effective in G0 phase
(d) Include the alkylating agents

28. Infections due to gram–negative bacilli have occurred when this agent has been used as a skin antiseptic
(a) Acetic acid
(b) Benzalkonium chloride
(c) Hexachlorophene
(d) Merbromin

29. Which one of the following compounds is used topically to treat scabies and pediculosis?
(a) Lindane
(b) Mupirocin
(c) Nitrofurazone
(d) Polymyxin B

30. Methenamine salts are used as urinary antiseptics. The reason why they lack systemic antibacterial action is that they are
(a) Not absorbed into the systemic circulation following oral ingestion
(b) Rapidly metabolized by liver drug– metabolizing enzymes
(c) Converted to formaldehyde only at low urinary pH
(d) Substrates for active tubular secretion

31. Which one of the following antiseptics promotes wound healing?
(a) Cetylpyridium
(b) Chlorhexidine
(c) Hexachlorophene
(d) None of the above

32. A patient with AIDS has an extremely high viral RNA titer. While blood is being drawn from this patient, the syringe is accidentally dropped, contaminating the floor, which is made of porous material. The best way to deal with this is to
(a) Completely replace the contaminated part of the floor
(b) Clean the floor with soap and water
(c) Seal the room and decontaminate with ethylene oxide
(d) Clean the floor with a 10% solution of household bleach

33. Certain anaerobic protozoan parasites lack mitochondria and generate energy rich compounds, such as acetyl–CoA, by means of enzymes present in organelles called hydrogenosomes. An important enzyme involved in this process is
(a) Cytochrome P450
(b) Glycerol – 3 – phosphate oxidase
(c) Hypoxanthine – guanine phosphoribosyltran-ferase
(d) Pyruvate – ferredoxin oxidoreductase

34. Which of the following compounds is a good substrate for hypoxanthine– guanine phosphoribosyltransferase in trypanosomes (but not mammals) and is eventually converted into metabolites that are incorporated into RNA?
(a) Allopurinol
(b) Alpha – difluoromethylornithine
(c) Glycerol
(d) Mebendazole

35. One chemotherapeutic strategy used to eradicate the blood-stream form of African trypanosomes is based on the absolute dependence of the organism on
(a) Cytochrome – dependent electron transfer
(b) Dihydropteroate synthesis
(c) Glycolysis
(d) Lactate dehydrogenase

36. Which of the following drugs enhances GABA actions on the neuromuscular junctions of nematodes and arthropods?
(a) Glutamic acid
(b) Ivermectin
(c) Picrotoxin
(d) Pyrantel pamoate

37. Which of the following drugs is an antimetabolite that inhibits a trypanosomal enzyme involved in putrescine synthesis?
(a) Alpha – difluoromethylornithine
(b) Alpha – fluorodeoxyuridine
(c) Metronidazole
(d) Polymyxin

38. Which one of the following enzymes is not unique to parasites?
(a) Dihydropteridine pyrophosphokinase
(b) Hypoxanthine–guanine phosphoribosyltrans-ferase
(c) Lanosterol demethylase
(d) Purine nucleoside phosphotransferase

39. Which of the following antimalarial drugs causes a dose–dependent toxic state that includes flushed and sweaty skin, dizziness, nausea, diarrhea, tinnitus, blurred vision, and impaired hearing?
(a) Amodiaquine
(b) Primaquine
(c) Pyrimethamine
(d) Quinine

40. Plasmodial resistance to chloroquine is due to
(a) Change in receptor structure
(b) Decreased carrier–mediated drug transport
(c) Increase in the activity of DNA repair mechanisms
(d) Induction of inactivating enzymes

41. This drug is the antimalarial agent most commonly associated with causing an acute hemolytic reaction in patients with glucose – 6 – phosphate dehydrogenase deficiency.
(a) Chloroquine
(b) Clindamycin
(c) Mefloquine
(d) Primaquine

42. This drug can clear trypanosomes from the blood and lymph nodes and is active in the late CNS stages of African sleeping sickness.
(a) Emetine
(b) Melarsoprol
(c) NIfurtimox
(d) Pentamidine

43. Which one of the following drugs is recommended as a single agent for oral treatment of uncomplicated malaria due to chloroquine–resistant P falciparum strains?
(a) Doxycycline
(b) Iodoquinol
(c) Primaquine
(d) Quinine

44. A missionary from Chicago is sent to work in a geographic region of a Cental American country wher onchocerca olvulus is endemic. Infections due to this tissue nematode (onchocerciasis) are a major cause of “river blindness”, since microfilariae migrate through subcutaneous tis-sues and concentrate in the eyes. Which one of the following drugs can be used prophylactically to prevent onchocerciasis?
(a) Bithionol
(b) Ivermectin
(c) Niclosamide
(d) Oxamniquine

45. In a patient with diffuse lymphoma, the oncologist suggests a treatment strategy that involves the initial administration of doxorubicin to obtain a significant log kill, followed by the cell cycle–specific drugs cytarabine and vincristine. This therapeutic strategy is called
(a) Pulse therapy
(b) Recruitment
(c) Rescue therapy
(d) Sequential blockade

46. Which one of the following statements about the mechanisms of action of drugs used in cancer chemotherapy is least accurate?
(a) Alkylatine agents commonly attack the nucleophilic N-7 position in guanine
(b) Anthracyclines intercalate with base pairs to block nucleic acid synthesis
(c) In steady doses, leuprolide inhibits the release of pituitary gonadotropins
(d) Mercaptopurine is an irreversible inhibitor of HGPRTase

47. Which of the following agents used in drug combination regimens to treat testicular carcinoma is most likely to cause nephrotoxicity?
(a) Bleomycin
(b) Cisplatin
(c) Etoposide
(d) Leuprolide

48. Which one of the following is least likely to be a mechanism of cancer cell resistance to antineoplastic drugs?
(a) Change in properties of a target enzyme
(b) Decreased activity of activating enzymes
(c) Increase in drug–metabolizing cytochrome P450
(d) Increase in DNA repair
(e) Increase in production of drug–trapping molecules

49. All of the following agents have been used in drug regimens for the treatment of breast carcinoma. Which one has specific activity in a subset of female breast cancers?
(a) Anastrozole (b) Doxorubicin
(c) Fluoxymesterone (d) Trastuzumab

50. Which cell involved in immune function recognizes foreign peptides bound of MHC class II molecules on the surface of APC cells, secretes interleukin-2, and initiates the cell-mediated immunity reaction responsible for host-versus-graft reactions?
(a) B lymphocyte
(b) Cytotoxic T lymphocyte
(c) Dendritic cell
(d) TH lymphocyte

Answers

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