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36 Cards in this Set
- Front
- Back
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28 year old chemist presents with MPTP exposure. It is a neurotoxin that destroys cells in the substantia nigra and creates symptoms of Parkinsons. MPTP can be accidentally produced during the illicit manufacture of MPPP, which has similar effects to heroin. What neurotransmitter is depleted?
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Dopamine
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Woman taking tetracycline exhibits photosensitivity. What are the clinical manifestations?
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rash on sun-exposed regions of the body
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Nondiabetic patient presents with hypoglycemia but low levels of C peptide. What is the diagnosis?
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Surreptitious insulin injection. Pro-insulin, made by the body, splits into insulin and c-peptide (connecting-peptide). In pharmaceutical insulin, c-peptide is not made. So, if someone is producing insulin endogenously, there will be c-peptide, but if someone is injecting insulin, there will not be c-peptide.
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Glucose-6-phosphate dehydrogenase deficiency (G6PD deficiency): inheritance pattern
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X-linked recessive, more prevalent among blacks
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G6PD deficiency: What is G6PD?
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It is an enzyme which makes NAPDH. NAPDH in turn, is an important substrate which makes glutathione reductase able to make reduced stated glutathione, which interms can donate an electron to an unstable oxygen species. Therefore G6PD is important in detoxifying free radiccals and peroxides.
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G6PD deficiency: What does it cause?
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Decreased NADPH in RBCs leads to hemolytic anemia due to poor RBC defense against oxidizing agents
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What are some oxidizing agents that can precipitate hemolytic anemia in G6PD deficiency?
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1. fava beans
2. sulfonamides (ie. Bactrim) 3. primaquine (an anti-parastic drug, anti-malarial drug) kills latent hypnozoite (liver) forms of malaria (Plasmodium vivax, P. ovale) 4. INH (anti-tuberculosis drugs) |
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Primaquine: What does it eradicate and what can it cause?
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It is the only agent that can eradicate the dormant hepatic forms of P. vivax and P. ovale; can cause hemolytic anemia in patients with G6PD deficiency.
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Why do you get Heinz bodies in G6PD deficiency?
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Free radicals damage the hemoglobin, which precipitates out as Heinz bodies. These RBCs are nibbled out by splenic cells, leading to extravascular hemolysis.
RBC obtain NAPDH exclusively from this pathway involving G6PD, therefore, RBCs are particularly vulnterable. Heinz bodies are also seen in other unstable hemoglobinopathies. |
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African-American man who goes to Africa develops a hemolytic anemia after taking malarial prophylaxis. What is the enzyme deficiency?
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Glucose-6-phosphate dehydrogenase
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27 yo female with a history of psychiatric illness now has urinary retention due to a neuroleptic. What do you treat it with?
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bethanechol
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What is bethanechol?
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It is a direct agonist of mACHR (muscarinic acetylcholine receptors), so it activates the parasympathetic system. Bethanechol is used for postoperative and neurogenic ileus and urinary retention. It activates bowel and bladder smooth muscle.
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Farmer presents with dyspnea, salivation, miosis, diarrhea, cramping, and blurry vision. What caused this, and what is the mechanism of action?
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Insecticide poisoning; ie. cholinesterase inhibitor poisoning (inhibits the enzyme that breaks down acetylcholine, so you have an excess of acetylcholine. Side effect profile of overdose of cholinesterase inhibitors mimics an excessive stimulation of the parasympathetic system (diarrhea, urination, miosis, bronchospasm, bradycardia, excitation of the CNS and skeletal muscle (ACh is the neurotransmitter for the NMJ) , lacrimation, sweating (sympathetic NS stimulates sweat glands via ACh release from postganglionic sympathetic fibers).
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If someone is poisoned with organophosphate (irreversible cholinesterase inhibitors such as insecticides),what is the treatment?
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Treatment goal is to decrease ACh activity, so treat with:
1. pralioxine: which regenerates active cholineasterase 2. anticholinergic: atropine (blocks muscarinic cholinergic MACh receptors) |
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Patient with recent kidney transplant is on cyclosporine for immunosuppression. He requires antifungal agent for candidiasis. What antifungal drug would result in cyclosporine toxicity?
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Ketoconazole; it is an inhibitor of the hepatic p-450 system which metabolizes drugs. Therefore, co-administration of ketoconazole would prevent cyclosporine from breaking down, leading to toxicity.
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What are the p-450 inhibitors?
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Isoniazid, Sulfonamides, Cimetidine, Ketoconazole, Erythromycin and Grapefruit juice
Inhibitors: Inhibitors Stop Cyber-Kids from Eating Grapefruit |
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What are the p-450 inducers?
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Quinidine, Barbiturates, Phenytoin, Rifampin, Griseofulvin and Carbamazepine
Inducers: Queen Barb takes Phen-phen and Refuses Greasy Carbs |
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What are some drugs that go through the p450 system?
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Warfarin, prednisone, digitoxin, quinidine, ketoconazole, propranolol, oral contraceptives.
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Man on several medications including antidepressants and antihypertensives has mydriasis and becomes constipated. What are the cause of his symptoms?
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TCA, tri-cyclic antidepressants have atropine-like (anticholinergic) side effects such as urinary retention and tachycardia
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What is atropine?
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a muscarinic antagonist
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What does atropine cause in terms of side effects?
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it blocks SLUD
blocks salivation: decreased secretions blocks lacrimation blocks urination: decreased urgency in cystitis blocks defecation; constipation in the eye, it increases puil dilation (mydriasis) and cycloplegia (paralysis of eye muscles responsible for visual accomodation) |
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55 yo post menopausal woman is on tamoxifen therapy. What is she at increased risk of acquiring?
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endometrial caricnoma
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Woman on MAO inhibitor has hypertensive crisis after a meal. What did she ingest?
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tyramine (wine or cheese)
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What is the mode of action for MAOi?
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MAOIs act by inhibiting the activity of monoamine oxidase, thus preventing the breakdown of monoamine neurotransmitters and thereby increasing their availability. There are two isoforms of monoamine oxidase, MAO-A and MAO-B. MAO-A preferentially deaminates serotonin, melatonin, epinephrine and norepinephrine. MAO-B preferentially deaminates phenylethylamine and trace amines. Dopamine is equally deaminated by both types.
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What are MAO inhibitors?
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Monoamine oxidase inhibitors (MAOIs) are a class of powerful antidepressant drugs prescribed for the treatment of depression. They are particularly effective in treating atypical depression, and have also shown efficacy in smoking cessation.
Due to potentially lethal dietary and drug interactions, MAOIs had been reserved as a last line of defense, used only when other classes of antidepressant drugs (for example selective serotonin reuptake inhibitors and tricyclic antidepressants) have been tried unsuccessfully. Recently, however, a patch form of the drug selegiline, called Emsam, was developed. It was approved for use by the FDA on February 28, 2006.[1] When applied transdermally the drug does not enter the gastro-intestinal system as it does when taken orally, thereby decreasing the dangers of dietary interactions associated with MAOI pills. |
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Why does mixing MAO inhibitors and foods high in tyramine cause a hypertensive crisis?
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The exact mechanism by which tyramine causes a hypertensive reaction is not well understood, but it is assumed that tyramine displaces norepinephrine from the storage vesicles.[4] This may trigger a cascade in which excessive amounts of norepinephrine can lead to a hypertensive crisis.
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What else (mixed with MAO inhibitors) other than tyramine foods can also cause a hypertensive crisis?
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meperidine (narcotic analgesic, aka Demerol)
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What are some foods high in tyramine?
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Examples of foods and drinks with potentially high levels of tyramine include fermented substances, such as Chianti and other aged wines, and aged cheeses. Liver is also a well-known source.
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After taking clindamycin, patient develops toxic megacolon and diarrhea. What is the mechanism of diarrhea?
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Clostridium difficile overgrowth.
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Man starts a medication for hyperlipidemia. He then develops a rash, pruritis and GI upset. What drug was it?
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niacin
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Patient is on carbamazepine. What routine workup should always be done?
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LFTs.
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What is carbamazepine used for?
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Carbamazepine (CBZ) is an anticonvulsant and mood stabilizing drug used primarily in the treatment of epilepsy and bipolar disorder.
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What is a comoon trade name for carbamazepine?
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Tegretol
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What are important side effects/toxicities for carbamazepine?
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diplopia, ataxia, induction of cytochrome p-450, blood dyscrasias (agranulocytosis, aplastic anemia), liver toxicity (always check LFTs)
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23 yo female who is on rifampin for TB prophylaxis and on birth confrol (estrogen) gets pregnant. Why?
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Rifampin augments estrogen metabolism in the liver, rendering it less effective.
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Patient develops cough and must discontinue catpopril. What is a good replacement drug, and why doesn't it have the same side effects?
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Losartan, an angiotensin II receptor antagonist, does not increase bradykinin as captopril does.
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