Pharmacology Questions Part 2 Answers and Rationale
Posted in Pharmacology by admin On March 31, 2010. 4 Comments
- Answer C. Glycocalyx is a viscous polysaccharide or polypeptide slime that covers microbes. It enhances adherence to surfaces, resists phagocytic engulfment by the white blood cells, and prevents antibiotics from contacting the microbe. Glycocalyx does not have the effects in options B-D.
- Answer B. The child can move his extremities and function in a normal fashion. This lessens stress associated with position restriction and promotes normal activity. Fear may not be eliminated. All lines can be dislodged. Even small catheters can be readily seen.
- Answer C. In patients unable to take oral nutrition, parenteral hyperalimentation is an option for providing nutritional support. High concentrations of dextrose, protein, minerals, vitamins, and trace elements can be provided. Dosing is not affected with options a and d. Crystalloid can provide free water but has very little nutritional benefits. Hyperalimentation can provide free water and considerable nutritional benefits.
- Answer D. A multilumen catheter contains separate ports and means to administer agents. An agent infusing in one port cannot mix with an agent infusing into another port. Thus, agents that would be incompatible if given together can be given in separate ports simultaneously.
- Answer A. Occlusion occurs with slow infusion rates and concurrent administration of some medications. Lipid occlusions may be treated with 70 percent ethanol or with 0.1 mmol/mL NaOH. Lipids provide essential fatty acids. It is recommended that approximately 4 percent of daily calories be EFAs. A deficiency can quickly develop. Daily essential fatty acids are necessary for constant prostaglandin production. Lipids are almost isotonic with blood.
- Answer C. Strict aseptic technique including the use of cap, mask, and sterile gown and gloves is require when placing a central venous line including a PICC. Options A, B, and D are incorrect statements. They increase the risk of infection.
- Answer C. Pain related to PICC insertion occurs with puncture of the skin. When inserting PICC lines, the insertion site is anesthetized so no pain is felt. The patient will not receive general anesthesia or sedation. Statement 2 is false. Unnecessary pain should be prevented.
- Answer B. Any air entering the right heart can lead to a pulmonary embolus. All air should be purged from central venous lines; none should enter the patient.
- Answer A. A special portacath needle is used to access the portacath device. A syringe is attached and the sample is obtained. One of the primary reasons for insertion of a portacath device is the need for frequent or long-term blood sampling. A vacutainer will exert too much suction on the central line resulting in collapse of the line. Only special portacath needles should be used to access the portacath device.
- Answer B. The actual access to the subclavian vein is still just under the clavicle, but by tunneling the distal portion of the catheter several inches under the skin the risk of migratory infection is reduces compared to a catheter that enters the subclavian vein directly and is not tunneled. The catheter is tunneled to prevent infection.
- Answer C. A foreign body in a blood vessel increases the risk of infection. Catheters that come outside the body have an even higher risk of infection. Most infections are caused by skin bacteria. Other infective organisms include yeasts and fungi. Options 1 and 4 are complications of a CVAD but are not the primary problem. Once placed, these lines do not cause pain and discomfort.
- Answer D. A solution containing heparin is used to reduce catheter clotting and maintain patency. The concentration of heparin used depends on the patient’s age, comorbidities, and the frequency of catheter access/flushing. Although patients have few complications, the device is not risk free. Patients may develop infection, catheter clots, vascular obstruction, pneumothorax, hemothorax, or mechanical problems (catheter breakage). Strict adherence to protocol enhances the longevity of central access devices. They routinely last weeks to months and sometimes years. The patient will be taught how to perform dressing changes at home.
- Answer A. Alkylating agents are highly reactive chemicals that introduce alkyl radicals into biologically active molecules and thereby prevent their proper functioning, replication, and transcription. Alkylating agents have numerous side effects including alopecia, nausea, vomiting, and myelosuppression. Nitrogen mustards have a broad spectrum of activity against chronic lymphocytic leukemia, non-Hodgkin’s lymphoma, and breast and ovarian cancer, but they are effective chemotherapeutic agents because of DNA cross-linkage. Alkylating agents are noncell cycle-specific agents.
- Answer C. Estrogen antagonists are used to treat estrogen hormone-dependent cancer, such as breast carcinoma. A well-known estrogen antagonist used in breast cancer therapy is tamoxifen (Nolvadex). This drug, in combination with surgery and other chemotherapeutic drugs reduces breast cancer recurrence by 30 percent. Estrogen antagonists can also be administered to prevent breast cancer in women who have a strong family history of the disease. Thyroxine is a natural thyroid hormone. It does not treat thyroid cancer. ACTH is an anterior pituitary hormone, which stimulates the adrenal glands to release glucocorticoids. It does not treat adrenal cancer. Glucagon is a pancreatic alpha cell hormone, which stimulates glycogenolysis and gluconeogenesis. It does not treat pancreatic cancer.
- Answer D. The time required to clear circulating cells before the effect that chemotherapeutic drugs have on precursor cell maturation in the bone marrow becomes evident. Leukopenia is an abnormally low white blood cell count. Answers A-C pertain to red blood cells.
- Answer A. Epoetin alfa (Epogen, Procrit) is a recombinant form of endogenous erythropoietin, a hematopoietic growth factor normally produced by the kidney that is used to induce red blood cell production in the bone marrow and reduce the need for blood transfusion. Glucagon is a pancreatic alpha cell hormone, which cause glycogenolysis and gluconeogenesis. Fenofibrate (Tricor) is an antihyperlipidemic agent that lowers plasma triglycerides. Lamotrigine (Lamictal) is an anticonvulsant.
- Answer A. Prostate tissue is stimulated by androgens and suppressed by estrogens. Androgen antagonists will block testosterone stimulation of prostate carcinoma cells. The types of cancer in options 2-4 are not androgen dependent.
- Answer A. Chemotherapy often induces vomiting centrally by stimulating the chemoreceptor trigger zone (CTZ) and peripherally by stimulating visceral afferent nerves in the GI tract. Ondansetron (Zofran) is a serotonin antagonist that bocks the effects of serotonin and prevents and treats nausea and vomiting. It is especially useful in single-day highly emetogenic cancer chemotherapy (for example, cisplatin). The agents in options 2-4 are selective serotonin reuptake inhibitors. They increase the available levels of serotonin.
- Answer C. With intrathecal administration chemotherapy is injected through the theca of the spinal cord and into the subarachnoid space entering into the cerebrospinal fluid surrounding the brain and spinal cord. The methods in options A, B, and D are ineffective because the medication cannot enter the CNS.
- Answer B. Leucovorin is used to save or "rescue" normal cells from the damaging effects of chemotherapy allowing them to survive while the cancer cells die. Therapy to rapidly reduce the number of cancerous cells is the induction phase. Consolidation therapy seeks to complete or extend the initial remission and often uses a different combination of drugs than that used for induction. Chemotherapy is often administered in intermittent courses called pulse therapy. Pulse therapy allows the bone marrow to recover function before another course of chemotherapy is given.
- Answer B. Prevent uric acid nephropathy, uric acid lithiasis, and gout during cancer therapy since chemotherapy causes the rapid destruction of cancer cells leading to excessive purine catabolism and uric acid formation. Allopurinol can induce myelosuppression and pancytopenia. Allopurinol does not have this function.
- Answer B. Medications administered intravesically are instilled into the bladder. Intraventricular administration involves the ventricles of the brain. Intravascular administration involves blood vessels. Intrathecal administration involves the fluid surrounding the brain and spinal cord.
- Answer C. The overall goal of cancer chemotherapy is to give a dose large enough to be lethal to the cancer cells, but small enough to be tolerable for normal cells. Unfortunately, some normal cells are affected including the bone marrow. Myelosuppression limits the body’s ability to prevent and fight infection, produce platelets for clotting, and manufacture red blood cells for oxygen portage. Even though the effects in options a, b, and d are uncomfortable and distressing to the patient, they do not have the potential for lethal outcomes that myelosuppression has.
- Answer A. Vomiting (emesis) is initiated by a nucleus of cells located in the medulla called the vomiting center. This center coordinates a complex series of events involving pharyngeal, gastrointestinal, and abdominal wall contractions that lead to expulsion of gastric contents. Catecholamine inhibition does not induce vomiting. Chemotherapy does not induce vomiting from autonomic instability. Chemotherapy, especially oral agents, may have an irritating effect on the gastric mucosa, which could result in afferent messages to the solitary tract nucleus, but these pathways do not project to the vomiting center.
- Answer A. Myelo comes from the Greek word myelos, which means marrow. Ablation comes from the Latin word ablatio, which means removal. Thus, myeloablative chemotherapeurtic agents destroy the bone marrow. This procedure destroys normal bone marrow as well as the cancerous marrow. The patient’s bone marrow will be replaced with a bone marrow transplant. Myelocytes are not muscle cells Tumors are solid masses typically located in organs. Surgery may be performed to reduce tumor burden and require less chemotherapy afterward.
- Answer C. Nausea and vomiting (N&V) are common side effects of chemotherapy. Some patients are able to trigger these events prior to actually receiving chemotherapy by anticipating, or expecting, to have these effects. N&V occurring post-chemotherapeutic administration is not an anticipatory event but rather an effect of the drug. N&V occurring during the administration of chemotherapy is an effect of the drug.
- Answer C. Only an unbound drug can be distributed to active receptor sites. Therefore, the more of a drug that is bound to protein, the less it is available for the desired drug effect. Less drug is available if bound to protein. Distribution to receptor sites is irrelevant since the drug bound to protein cannot bind with a receptor site. Metabolism would not be increased. The liver will first have to remove the drug from the protein molecule before metabolism can occur. The protein is then free to return to circulation and be used again.
- Answer C. Drugs and drug metabolites with molecular weights higher than 300 may be excreted via the bile, stored in the gallbladder, delivered to the intestines by the bile duct, and then reabsorbed into the circulation. This process reduces the elimination of drugs and prolongs their half-life and duration of action in the body. Hepatic clearance is the amount of drug eliminated by the liver. Total clearance is the sum of all types of clearance including renal, hepatic, and respiratory. First-pass effect is the amount of drug absorbed from the GI tract and then metabolized by the liver; thus, reducing the amount of drug making it into circulation.
- Answer C. Drug B will induce the cytochrome p-450 enzyme system of the liver; thus, increasing the metabolism of Drug A. Therefore, Drug A will be broken down faster and exert decreased therapeutic effects. Drug A will be metabolized faster, thus reducing, not increasing its therapeutic effect. Inducing the cytochrome p-450 system will not increase the adverse effects of Drug B. Drug B induces the cytochrome p-450 system but is not metabolized faster. Thus, the therapeutic effects of Drug B will not be decreased.
- Answer A. Epinephrine (adrenaline) rapidly affects both alpha and beta adrenergic receptors eliciting a sympathetic (fight or flight) response. Muscarinic receptors are cholinergic receptors and are primarily located at parasympathetic junctions. Cholinergic receptors respond to acetylcholine stimulation. Cholinergic receptors include muscarinic and nicotinic receptors. Nicotinic receptors are cholinergic receptors activated by nicotine and found in autonomic ganglia and somatic neuromuscular junctions.
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Answer to question number 8 should be D.
The answer “C” for problem number 6 is incorrect. The justification for the answer “C” actually justifies answer letter B. So as Question #8 (answer should be letter D), Question #20 (answer should be letter D), Question #25 (answer should be letter D), Question #26 (answer should be letter D). Questions #25, 28 and 29 rationales were so vague.
i can’t understand number 25…it seems so vague as well as the rationale..
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