The correct answer is B. The patient is presenting with signs and symptoms highly suggestive of hypoparathyroidism. This condition occurs most frequently after thyroidectomy or the removal of a parathyroid adenoma. Hypoparathyroidism is characterized by severe hypocalcemia and hyperphosphatemia, resulting in tetany, carpopedal spasms, muscle and abdominal cramps, and tingling of the lips and hands. A positive Chvostek sign (tapping the face in front of the ear elicits tetany) and Trousseau sign (abnormal muscular contractions elicited by applying a blood pressure cuff) will often be noted. Since the blood calcium levels are often very low, either calcium gluconate or vitamin D preparations should be administered to correct the condition. Vitamin D preparations, such as ergocalciferol (Vitamin D₂), elevate calcium levels, and decrease phosphate levels.

Bumetanide (choice A) is a loop diuretic used to treat various edematous states; this product is contraindicated in patients with hypoparathyroidism because it decreases blood calcium levels, which will worsen the condition.

Levothyroxine (choice C) is used as replacement therapy for diminished or absent thyroid function. Although patients with hypoparathyroidism may also be hypothyroid, the use of levothyroxine will not correct the hypocalcemia and hyperphosphatemia.

Niacin (choice D) is used to treat pellagra and as an adjuvant agent to treat hyperlipidemia.

The use of pamidronate (choice E) in a patient with hypoparathyroidism is contraindicated since this agent is used to treat hypercalcemia and would subsequently worsen the patient's hypocalcemia.

The correct answer is A. Organophosphate insecticides such as parathion function as acetylcholinesterase inhibitors, producing increased acetylcholine levels at all cholinergic synapses. Although both muscarinic and nicotinic receptors are stimulated, the muscarinic effects are usually identified first. Treatment with atropine is generally indicated with organophosphate intoxication.

Muscarinic (choice B) and nicotinic (choice D) receptors are not directly affected by organophosphates. The drug's actions are completely indirect; increased stimulation is due to the lengthened half-life of acetylcholine at the synapse.

The neuronal lipid bilayer (choice C) is disturbed by inhalational anesthetic drugs. Although the mechanism of action is poorly understood, it is believed to be a consequence of altered neuronal transmission and ion channel dysfunction.

Nerve conduction is blocked when local anesthetics bind to and inactivate voltage-gated sodium channels (choice E).

The correct answer is A. You must be familiar with the maintenance dose equation to answer this question:

M.D. = Cl x Cp_ss/F, where

M.D. = maintenance dose

Cl = clearance

Cp_ss = plasma concentration at steady state

F = bioavailability

In this case, M.D. is 10 mg/min; F, or how much drug is absorbed, is 1 (100%) because drugs administered I.V. are completely absorbed. (F becomes important when drugs are given orally.) Cp_ss = 20 mg/L; it takes 4 -5 half-lives to achieve steady state, so this drug has been administered for a time period equaling 6 half-lives.

Solving,

10 mg/mL = Cl x 20 mg/mL

Cl = 0.5 L/min

The correct answer is A. The cytochrome P-450 mixed-function oxidase system is located on smooth endoplasmic reticulum in liver cells. This system is involved in the detoxification of some drugs and other exogenous compounds (barbiturates, carcinogenic hydrocarbons, steroids, carbon tetrachloride, alcohol, insecticides), and its growth can be stimulated by exposure (particularly chronic exposure) to these agents. As a consequence, cells adapted to one drug can more rapidly metabolize the other drugs and compounds handled by the P-450 system.

The correct answer is A. Alpha-1 receptors activate phospholipase C via the G protein Gq. Phospholipase C cleaves the membrane phospholipid phosphatidylinositol 4,5-bisphosphate to produce the products, inositol triphosphate (IP₃) and diacylglycerol (DAG). IP₃ releases intracellular calcium from the endoplasmic reticulum, and would therefore generate a robust signal. DAG activates protein kinase C.

Beta-1 adrenergic receptors (choice B) stimulate adenylate cyclase via the G protein Gs, leading to an increase in intracellular cAMP. All beta adrenergic receptors share a common mechanism of action.

Dopamine-1 receptors (choice C) stimulate adenylate cyclase via the G protein Gs. This leads to an increase in intracellular cAMP.

Muscarinic-2 acetylcholine receptors (choice D) inhibit adenylate cyclase via the G protein Gi. This leads to an decrease in intracellular cAMP. Muscarinic receptors also stimulate the opening of potassium channels in the heart, via the beta and gamma subunits of Gi.

Nicotinic acetylcholine receptors (choice E) are ligand-gated ion channels. When stimulated, they allow sodium ions to enter the cell.

The correct answer is B. The half-life of a medication is the time required for one-half the total amount of the medication to be excreted from the body. For any given first-order elimination process, 50% of the initial amount of drug is eliminated at the end of the first half-life, 50% of the remaining amount of drug in the body is eliminated at the end of the second half-life, and so on. Therefore, after 3 hours 50% of the gentamicin will be remaining in the body. After another 3 hours (6 hours total), 50% of the remaining 50% will be eliminated. In other words, after 6 hours, 75% of the gentamicin will be eliminated, and 25% of the initial dose will remain.

The correct answer is B. Tetracyclines, such as doxycycline, are antibiotics commonly used to treat rickettsial infections, such as Rocky Mountain spotted fever and typhus, and Lyme disease, caused by a spirochete. They are also used for acne, various sexually transmitted diseases, and for susceptible organisms in penicillin-allergic patients. Doxycycline and minocycline are tetracyclines excreted largely by nonrenal routes. Their half-lives and serum concentrations are not significantly increased in patients with renal impairment. Both doxycycline and minocycline are secreted in an inactive form into the intestinal lumen and eliminated in the feces; therefore, their half-lives are largely independent of renal function. The other tetracyclines listed are concentrated by the liver in the bile and excreted in the urine and feces unchanged. Therefore, dosage adjustments need to be made in patients with renal impairment because of the accumulation of the drug in the body. In other words, demeclocycline (choice A), methacycline (choice C), oxytetracycline (choice D), and tetracycline (choice E) will accumulate in patients with renal impairment. Hence, doxycycline would be the best treatment option for this patient.

The correct answer is A. Acetylcysteine (N-acetylcysteine) is the antidote for acetaminophen overdose. It likely acts by replenishing hepatic stores of glutathione, which become depleted in the effort to metabolize the acetaminophen. It is most effective if administered within 10 hours of acetaminophen ingestion.

Atropine (choice B) is a muscarinic receptor antagonist used in the treatment of cholinesterase inhibitor poisoning.

Penicillamine (choice C) is a chelating agent used to treat poisoning with copper, lead, arsenic, and gold.

Pralidoxime (choice D) is an acetylcholinesterase reactivating agent that is used in organophosphorus cholinesterase inhibitor poisoning.

Protamine (choice E) is used for heparin overdose. Protamine is a basic peptide that binds heparin to form a stable complex devoid of anticoagulant activity.

The correct answer is A. To answer this question you have to identify two pieces of information. First, you have to recognize that it is about vitamin deficiency acquired by antibiotic therapy (vitamin K is made by bacteria in the gut) and then recognize the deficiency syndrome that would be produced (bleeding tendency secondary to the inability to make clotting factors II, VII, IX, X, and proteins C and S). The other vitamin/syndrome associations are as follows:

Vitamin D deficiency can lead to bony abnormalities (choice B).

Vitamin A deficiency can result in decreased night vision (choice C).

Vitamin B₁₂ and thiamine deficiency can lead to neurological defects (choice D).

Vitamin C deficiency can lead to scurvy (choice E).

The correct answer is C. The antineoplastics, as a class of medications, are associated with several common side effects, such as nausea, vomiting, alopecia, and bone marrow suppression. However, some antineoplastics are associated with specific types of toxicity. For example, doxorubicin and daunorubicin are associated with cardiotoxicity. These agents can cause congestive heart failure and/or cardiomyopathy for up to several weeks after the discontinuation of therapy. A patient with cardiotoxicity secondary to doxorubicin may present with a persistently reduced voltage of the QRS complex, a prolonged systolic time interval, and a reduced ejection fraction. This agent is also commonly associated with the development of alopecia, bone marrow depression, and stomatitis.

Bleomycin (choice A) may produce pulmonary fibrosis, edema of the hands, stomatitis, and alopecia.

Cisplatin (choice B) is associated with severe nausea and vomiting, renal dysfunction, and acoustic nerve dysfunction.

Etoposide (choice D) most commonly causes alopecia and bone marrow depression.

Vincristine (choice E) causes peripheral neuritis, areflexia, muscle weakness, paralytic ileus, and mild bone marrow depression.

The correct answer is B. This patient is exhibiting dystonia, an acute extrapyramidal side effect that can be a consequence of neuroleptic therapy. Acute dystonic reactions generally occur within the first few days of the initiation of neuroleptic therapy, tend to occur more frequently in children and young adults, and occur in males more often than females. The sustained eye deviation described in the question is a form of dystonia called an oculogyric crisis. These reactions are reversible with antihistamines (e.g., diphenhydramine), anticholinergic drugs (e.g., benztropine), or diazepam. All of the other answer choices can also be consequences of neuroleptic therapy.

Akathisia (choice A) is an extrapyramidal syndrome characterized by a feeling of restlessness, frequent, repetitive stereotyped movements and an inability to sit still for more than a short period of time. It usually occurs during the first few months of drug use.

Neuroleptic malignant syndrome (choice C) is a rare, but potentially fatal syndrome that usually occurs within 10 days of starting neuroleptic therapy. Clinical manifestations include fever, encephalopathy, muscle rigidity, dystonia, diaphoresis, tachycardia, and labile blood pressure.

Parkinsonism (choice D), as the name implies, is similar to Parkinson's disease: mask-like facies, drooling, tremors, pill-rolling motion, cogwheel rigidity, and shuffling gait all may be present. Parkinsonism can be produced by neuroleptic drugs, usually beginning about three weeks after the initiation of therapy.

Tardive dyskinesia (choice E) is an often irreversible syndrome characterized by involuntary, choreoathetoid movements in patients treated with antipsychotic medications. The frequency of tardive dyskinesia increases with age and with the length of therapy. This disorder would be unlikely to occur within a few days of the initiation of drug therapy.

The correct answer is E. Lactic acidosis is a condition characterized by the accumulation of excess lactic acid in the blood. Normally, the principle sources of lactic acid are erythrocytes, skeletal muscle, and the integument. Lactic acidosis is not uncommon in any severely ill patient suffering from respiratory or hepatic failure, cardiac decompensation, septicemia, or bowel infarction. Cases of lactic acidosis have also occurred in patients taking metformin. Metformin is a biguanide oral hypoglycemic agent used as an adjunct to diet in the treatment of non-insulin dependent diabetes. The risk for developing this disorder is increased in renally impaired patients, such as the patient in this question. Furthermore, lactic acidosis occurs more frequently in those taking nephrotoxic medications such as aminoglycosides and radiological contrast dyes. The other medications are not associated with the development of lactic acidosis.

Clonidine (choice A) is a centrally acting antihypertensive agent typically used in the treatment of refractory hypertension.

Enalapril (choice B) is an angiotensin-converting enzyme inhibitor used in the management of hypertension and congestive heart failure.

Furosemide (choice C) is a loop diuretic used in the management of hypertension and various edematous states.

Glyburide (choice D) is a sulfonylurea antidiabetic agent that is used as an adjunct to diet to lower blood glucose levels in patients with non-insulin dependent diabetes mellitus.

The correct answer is C. The only conclusion that can be drawn from this data is that Drug X is less efficacious than Drug Y. Efficacy is defined as the maximum effect that can be produced by a drug, regardless of dose. Drug X can only produce a 50% change in resistance, whereas Drug Y can produce a 75% change in resistance. Therefore, Drug X is less efficacious than Drug Y.

A volume of distribution (choice A) is the ratio of the amount of drug in the body to its plasma concentration. In this experiment, we do not know the total amount of drug used or the plasma concentration. For that matter, we do not even know if this is an in vivo experiment. Thus, no conclusions can be drawn about volume of distribution.

The half-life (choice B) is the time it takes for the concentration of a drug to fall 50% from its previous measurement. There is no information given to determine half-life.

The potency (choice D) is the dose or concentration required to produce 50% of the drug's maximal effect. We cannot determine the potency of Drug Y from this question.

The LD50 (choice E) is the dose that causes death in 50% of a population of subject. The experiment described above does not describe a population study, nor does it give any indication about the toxicity of the drug.

The correct answer is E. First, it is necessary to know that it is the uncharged, lipid-soluble form that can be rapidly absorbed. For an acid: HA <-------> H⁺ + A^-. Therefore, the protonated form is uncharged. The Henderson-Hasselbalch equation is:

pH = pKa - log[protonated form/unprotonated form]

In this case,

2.0 = 3.0 - log [HA/A^-]

1.0 = log [HA/A^-]

10 = HA/A^- = 10/1

HA/(HA + A^-) = 10/(10 + 1) = 91%, or approximately 90%

The correct answer is E. Priapism is characterized by the development of a painful erection for an extended period of time. When untreated, priapism can cause severe penile damage that can culminate in impotence. Administration of the antidepressant drug trazodone has been associated with priapism in a number of patients. In patients with prolonged or inappropriate penile erection, this medication should be discontinued and medical attention should be sought immediately. Injection of alpha-adrenergic stimulants, such as norepinephrine or epinephrine, may be successful in treating the priapism. Surgical intervention is necessary for the treatment of trazodone-induced priapism in many instances.

Atenolol (choice A) is a beta-1 adrenergic antagonist indicated for the treatment of hypertension. This agent is commonly associated with impotence in males.

Furosemide (choice B) is a loop diuretic indicated for the treatment of edema and hypertension; electrolyte abnormalities are the most common side effects seen with this agent.

The sulfonylurea glyburide (choice C) is an oral hypoglycemic agent indicated for the treatment of type 2 diabetes; hypoglycemia is the most common side effect of this agent.

Paroxetine (choice D) is a selective serotonin reuptake inhibitor (SSRI) used for the treatment of depression. This agent is commonly associated with impotence in males.

The correct answer is D. The rule of thumb is that the plasma concentration will reach 50% in one half-life, 75% in two half-lives, 87.5% in three half-lives, etc., so that the difference between the current drug level and 100% halves with each half-life. In this instance, it takes two half-lives to reach 75%. The half-live of this drug is 6 hours, so two half-lives is 12 hours.

The correct answer is A. The cephalosporins are a group of bactericidal antibiotics with broad gram-negative and gram-positive coverage; their anaerobic coverage varies. These agents are inhibitors of bacterial cell wall synthesis.

 

In general, progression from first to third generation generally yields a broadening gram-negative spectrum, loss of efficacy against gram-positive organisms, increased efficacy against resistant organisms, and increased cost. The first-generation cephalosporins are commonly used to treat skin and skin structure infections and urinary tract infections. They are also used prophylactically before surgical procedures.

The correct answer is E. Caffeine inhibits phosphodiesterase and thereby prevents cAMP from being degraded. Consequently, cAMP continues to activate protein kinase A, which results in both glycogen and triglyceride breakdown.

Caffeine has no direct or indirect effect on adenylyl cyclase (choice A).

Caffeine does not directly interact with glycogen phosphorylase (choice B) or hormone-sensitive lipase (choice C) and cannot allosterically activate these enzymes. However, because cAMP is not degraded due to the action of caffeine on phosphodiesterase, the cAMP will continue to activate protein kinase A. In turn, activation of protein kinase A will lead to phosphorylation of glycogen phosphorylase and hormone-sensitive lipase, resulting in glycogen and triglyceride breakdown.

Protein kinase A is not phosphorylated under normal physiological circumstances, and therefore caffeine cannot inhibit its dephosphorylation (choice D).

The correct answer is D. Serum sickness is a condition commonly caused by hypersensitivity to drugs. It is suggested that the drug acts as a hapten, which binds to plasma proteins. This drug-protein complex is recognized as being foreign to the body and induces the serum sickness. Common signs and symptoms of serum sickness include fever, cutaneous eruptions (morbilliform and/or urticarial), lymphadenopathy, and arthralgias. Erythema multiforme may also appear in severe cases. With respect to cefaclor, the incidence of serum sickness is much higher in infants and children than in adults. Due to the severity of the signs and symptoms in this patient, oral prednisone and diphenhydramine should be administered. The prednisone will treat the arthralgias and the skin rash and the diphenhydramine will alleviate the urticaria.

The use of aspirin (choice A) in a child with a fever is not indicated due to the risk of Reye syndrome. If the patient had not completed his antibiotic therapy and/or signs and symptoms of the infection were still present, switching the antibiotic to a non-beta lactam would be indicated.

Prescribing erythromycin (choice B) for a patient with no signs or symptoms of infection would not be indicated.

Intravenous penicillin (choice C) would not be indicated since there is no infection in this patient, and IV penicillin is reserved for serious infections. In fact, penicillin administration is the most common cause of serum sickness.

Topical betamethasone (choice E) may help to treat the rash and urticaria; however, oral prednisone and diphenhydramine would produce more symptomatic relief.

The correct answer is B. Rofecoxib is an anti-inflammatory drug that exhibits anti-inflammatory, analgesic, and antipyretic effects. This agent is classified as a selective cyclooxygenase -2 (COX-2) enzyme inhibitor. COX-1 is involved in production of prostaglandins that are important in renal blood flow, blood clotting, and protection of the GI lining. COX-2 appears to be involved in the production of prostaglandins involved in inflammation and pain. COX-2 inhibitors are indicated for the relief of pain and inflammation caused by osteoarthritis and rheumatoid arthritis, management of acute and chronic pain caused by inflammation in adults, as well as management of primary dysmenorrhea. Since COX-2 inhibitors do not inhibit COX-1, there is much less irritation of the gastrointestinal tract than with nonspecific COX inhibitors.

CNS-related side effects (choice A) are rare with both agents and have approximately the same incidence of occurrence in both agents.

The anti-inflammatory effects (choice C) and antipyretic effects (choice D) of both agents are approximately the same.

Neither agent has any opioid analgesic properties (choice E).

The correct answer is C. The half-life of a drug can be determined using the following equation:

t_1/2 = (0.693 × Vd)/Cl

 

The correct answer is A. This child is presenting with signs and symptoms of tinea corporis (tinea circinata or body ringworm). Patients with this condition often present with ring-shaped lesions that have an advancing scaly border and central clearing, occasionally with hyperpigmentation. Laboratory examination will reveal hyphae that can be demonstrated by removing the peripheral scales and examining them microscopically using KOH. This condition is commonly contracted by playing with an infected cat. Trichophyton rubrum is the most common dermatophyte associated with this condition. Tinea corporis is usually treated with topical antifungal creams, such as clotrimazole, miconazole, or econazole. Treatment is generally continued for 1-2 weeks after clinical clearing is noted.

Doxepin cream (choice B) is a used as a topical antipruritic cream.

Both halobetasol propionate cream (super-potent corticosteroid, choice C) and hydrocortisone acetate cream (low potency corticosteroid, choice D) are used to treat dermatologic disorders associated with some degree of inflammation. Occasionally, topical corticosteroids are used in conjunction with the topical antifungals to help treat the associated itch and inflammation. However, these agents are generally used alone.

Mupirocin (choice E) is a anti-infective agent indicated for the topical treatment of impetigo.

The correct answer is D. Don't forget to read the last sentence (the actual question) in a question first - it can save you time. In this question, the only important elements are "cancer chemotherapy," "5-FU," and "analog in DNA synthesis." The answer is thymine; 5-FU stand for 5-fluorouracil, which can be a metabolic analog of either uracil (in RNA, not DNA) or thymine. Substitution of these analogs impairs DNA synthesis of actively proliferating cells, hopefully with a greater effect on rapidly growing tumor cells than on normal cells in the body.

Adenine (choice A) is a purine, rather than pyrimidine, base and is unaffected by 5-FU.

Cytosine (choice B) is a pyrimidine, but is sufficiently different biochemically from uracil and thymine, so as not to be a target.

Guanine (choice C) is a purine, rather than pyrimidine, and is unaffected by 5-FU.

Uracil (choice E) can be replaced by 5-FU, but only occurs in RNA, not DNA. Affects on RNA are bad for the cell, but do not destroy genetic information.

The correct answer is C. The patient is an alcoholic, and alcohol normally enhances the cytochrome P450 system in the smooth endoplasmic reticulum (SER) of the liver. This system is responsible for the metabolism of drugs, hence, the low theophylline levels are most likely due to enhanced liver metabolism. The hepatocyte SER undergoes hyperplasia as a response to alcohol ingestion and synthesizes the enzyme gamma-glutamyl transferase (GGT). An elevation of GGT in this particular patient would help confirm the likelihood of increased hepatic drug metabolism as the cause of low drug levels.

Cirrhosis of the liver (choice A) would likely increase the serum levels of theophylline because of poor metabolism of the drug.

Decreased absorption of the drug (choice B) in the gastrointestinal tract is a possible choice. However, the history of excess alcohol intake and lack of a history of malabsorption suggest increased hepatic metabolism.

Increased clearance of theophylline in the urine (choice D) implies an increase in the glomerular filtration rate, which would not be expected in this patient.

Since the patient's wife is administering the medication, noncompliance (choice E) is highly unlikely. However, in most circumstances, the lack of an expected response to a medication is due to patient noncompliance until proven otherwise.

The correct answer is D. This is a drug interaction question that is essentially asking "which of the following medications will become less effective when combined with antacids." Based on the answer choices, only tetracycline blood levels will be decreased dramatically when taken concomitantly with antacids. When antacids are administered with tetracycline, the two agents will bind together and precipitate in the intestinal tract; hence, the medication will not be absorbed. Tetracycline is a bacteriostatic agent with mild to moderate gram-negative and gram-positive coverage. It is also effective in the treatment of rickettsial, spirochetal, and chlamydial infections. It is primarily used for the treatment of uncomplicated gonococcal infections and acne vulgaris.

Clindamycin (choice A) is a bacteriostatic agent with anaerobic coverage used in the treatment of life-threatening infections when less toxic alternatives are not available. It is commonly used in dentistry, but not for the treatment of acne.

Erythromycin (choice B) is a bacteriostatic agent that has moderately broad gram- negative, gram-positive, and anaerobic coverage. It is generally considered second-line therapy for the treatment of acne vulgaris.

Isotretinoin (choice C) is indicated for the treatment of severe recalcitrant acne. Its non-FDA approved uses include keratinization disorders, T-cell lymphoma, and various forms of skin cancers.

Trimethoprim/sulfamethoxazole (choice E) is a bacteriostatic agent with moderate gram-positive and gram-negative coverage. It is primarily used in the treatment of urinary tract infections and acne vulgaris as a second-line agent.

The correct answer is D. The volume of distribution of a drug can be determined using the following equation:

t_1/2 = (0.693 x Vd)/CL

Therefore, 10 hours = (0.693 x Vd)/(4.0 L/hour),

40 hours = 0.693 x Vd,

Vd = 58 L which is approximately 60 L

The correct answer is B. First-order kinetics, when applied to the concept of cytotoxicity, means that the drug will kill a constant proportion of tumor cells (rather than a constant number, choice A). The log kill hypothesis refines this by stating that the magnitude of killing by a cytotoxic agent is a logarithmic function. Therefore, a drug producing a 3-log kill will reduce 10¹² cells to 10⁹, or will reduce 10⁶ cells to 10³ (three orders of magnitude in either case). This hypothesis accounts for the far better results observed with chemotherapy when the total tumor burden is low.

The half-life of the drug (choice C) does not determine the number of cells killed, assuming an adequate dose is given.

Choices D and E are both reflections of cell cycle specificity, the ability of a drug to specifically kill cells in a particular phase of the cell cycle (eg, S phase or G₀ phase), and are unrelated to first-order kinetics.

The correct answer is G. Flumazenil is an antagonist at the benzodiazepine receptor. It has no effect on other CNS depressants, such as barbiturates or alcohol.

Acetylcysteine (choice A) is the drug of choice for treatment of overdose of acetaminophen, the active ingredient in Tylenol.

Atropine (choice B) is a muscarinic antagonist used in cases of acetylcholinesterase inhibitor overdose.

Bicarbonate (choice C) infusions may be given to alkalinize the urine and enhance the excretion of acidic drugs (e.g., aspirin).

CaNa₂EDTA (choice D) is used as a chelator in lead poisoning.

Deferoxamine (choice E) is an effective chelator for poisoning with iron salts.

Ethanol (choice F) is used in cases of methanol and ethylene glycol poisoning. Administration of EtOH in cases of diazepam overdose would be completely inappropriate because CNS depressants are additive.

Physostigmine (choice H) is used in cases of anticholinergic agent overdose.

Pralidoxime (choice I) is an acetylcholinesterase reactivating agent used in cases of organophosphorus acetylcholinesterase inhibitor overdose.

Protamine (choice J) is administered to reverse the anticoagulant effects of heparin overdose.

The correct answer is B. Long-term use of high IV doses of amphetamine almost inevitably induces a paranoid psychosis that can be severe enough to bring patients to psychiatric attention. Fortunately, the more florid symptoms fade within a few days, and the patients usually eventually recover, although persistence of delusional ideas, confusion, and memory loss may last months. The acutely agitated psychotic state can be treated with either chlorpromazine 25 to 50 mg IM or haloperidol 2.5 to 5 mg IM. Ammonium chloride 500 mg po q 4 h can be added to the regimen to acidify the urine and hasten amphetamine excretion.

Activated charcoal (choice A) absorbs residual compounds in the stomach after oral ingestion of drugs or poisons.

Deferoxamine (choice C) chelates iron and increases its clearance from the body.

Ipecac (choice D) induces vomiting and is useful for orally ingested drugs.

Naloxone (choice E) is an opiate antagonist.

The correct answer is B. Nausea and vomiting may be the most frequent and prominent adverse reactions seen in antineoplastic therapy, especially from the patient perspective. Antineoplastics can be categorized according to their emetogenic potential based on the frequency of emesis. Level 1 is the least emetogenic, and level 5 is the most emetogenic. Dacarbazine is a level 5 agent.

Bleomycin (choice A), hydroxyurea (choice C), mercaptopurine, (choice D), and vincristine (choice E) are all level 1 agents. Below is a partial table of antineoplastic agents based on their emetogenic potential.

 

The correct answer is D. The rule of thumb is that the levels decrease by half every half-life. Therefore, 50% will remain after one half-life, 25% will remain after two half-lives, 12.5% will remain after three half-lives, and 6.25% will remain after four half-lives. The half-life of this drug is 9 hours, so it will reach approximately 6% of steady state levels in 36 hours.

The correct answer is A. This patient is most likely suffering from an anticholinergic overdose, which would produce the symptoms described in the question. The probable culprit is Jimson weed, a naturally growing plant that contains antimuscarinic agents. This plant is often cultivated or field-collected and its leaves brewed in a tea.

Cholinomimetics (choice B), such as those in insecticides, can cause miosis, excessive salivation and sweating, hyperactive bowel sounds with abdominal cramping and diarrhea, anxiety, agitation, seizures, and coma. Muscle fasciculations may occur, followed by flaccid paralysis. Death may result from flaccid paralysis of respiratory muscles.

Opioids (choice C) can cause sleepiness, lethargy, or coma, miosis, cool skin, hypoventilation, hypotension, bradycardia, and decreased bowel sounds.

Salicylates (choice D) can cause hyperventilation, hyperthermia, anion gap metabolic acidosis, dehydration, potassium loss, and confusion, lethargy, or coma.

Sedative-hypnotics (choice E) can cause disinhibition at low doses, and increasing central nervous system depression (lethargy, stupor, coma) with higher doses.

Stimulants (choice F) can cause agitation, mydriasis, and tachycardia. The best way to distinguish stimulant overdose from anticholinergic overdose is the skin, which is sweaty with stimulants and dry with anticholinergics. Stimulants can also cause arrhythmias, seizures, psychosis, and hyperthermia.