Medication Calculations
A nurse is preparing to administer an IV fluid bolus of 200 mL dextrose 5% in water over 30 min. The drop factor of the manual IV tubing is 15 gtt/mL. The nurse should set the manual IV infusion to deliver how many gtt/min? (Round the answer to the nearest whole number. Use a leading zero if it applies. Do not use a trailing zero.)
100 gtt/min
Correct Answer Rationale:
Ratio and Proportion and Desired Over Have
STEP 1: What is the unit of measurement the nurse should calculate? gtt/min
STEP 2: What is the volume the nurse should infuse? 200 mL
STEP 3: What is the total infusion time? 30 min
STEP 4: Should the nurse convert the units of measurement? No
STEP 5: Set up an equation and solve for X.
Volume (mL)/Time (hr) x drop factor (gtt/mL) = X mL/hr
200 mL/30 min x 15 gtt/mL = X gtt/min
100 = X
STEP 6: Round if necessary.
STEP 7: Reassess to determine whether the amount to administer makes sense. If the prescription reads 200 mL dextrose 5% in water IV to infuse over 30 min, it makes sense to administer 100 gtt/min. The nurse should set the manual IV infusion to deliver 200 mL dextrose 5% in water IV at 100 gtt/min.
Which foods can trigger a hypertensive crisis in patients taking phenelzine?
Answer: Salami, wine, hard cheeses
Rationale: Tyramine-rich foods interact with MAOIs causing hypertensive crisis.
What is the maintenance range for lithium levels?
Maintenance range is 0.6–1.2 mEq/L.
Why is matching the antimicrobial spectrum to the specific pathogen important?
a) It reduces healthcare costs only
b) It prevents all side effects
c) The drug should be active against the pathogen but no broader than required
d) Broad-spectrum antibiotics are always more effective
Answer: c) The drug should be active against the pathogen but no broader than required
Rationale: A prime rule of antimicrobial therapy is to match the drug with the bug. The antimicrobial should be active against known or suspected pathogens, but its spectrum should be no broader than required. Using unnecessarily broad-spectrum agents when narrower spectrum drugs would suffice can lead to resistance development and disruption of normal flora. The drug should be selected based on its effectiveness against the specific causative pathogen.
What is a possible contraindication for tamoxifen use in cancer prevention?
Answer: History of DVT Rationale: Tamoxifen increases clot risk.
A nurse is caring for a client who is postoperative following an appendectomy and is prescribed D5 lactated Ringer's at 150 mL/hr by continuous IV infusion for 12 hr. The drop factor of the manual IV tubing is 20 gtt/mL. The nurse should set the manual IV infusion to deliver how many gtt/min? (Round the answer to the nearest whole number. Use a leading zero if it applies. Do not use a trailing zero.)
50 gtt/min
Correct Answer Rationale:
Follow these steps to calculate the infusion rate using the Ratio and Proportion or Desired Over Have method of calculation:
Step 1: What is the unit of measurement the nurse should calculate? gtt/min
Step 2: What is the volume the nurse should infuse? 150 mL
Step 3: What is the total infusion time? 1 hr
Step 4: Should the nurse convert the units of measurement? Yes (min does not equal hr)
1 hr = 60 min
Step 5: Set up an equation and solve for X.
Volume (mL)X gtt/min = × Drop factor (gtt/mL)Time (hr)
150 mL20 gttX gtt/min = × 60 min1 mL
X gtt/min = 50 gtt/min
Step 6: Round if necessary.
Step 7: Determine whether the amount to administer makes sense. If the prescription reads D5 lactated Ringer's 150 mL continuous IV infusion for 12 hr, it makes sense to administer 50 gtt/min. The nurse should set the manual IV infusion to deliver D5 lactated Ringer's IV at 50 gtt/min.
What are at least two potential adverse effects of MAOIs?
Answer: Orthostatic hypotension, tyramine-induced crisis, serotonin syndrome risk
Rationale: MAOIs interact with sympathomimetics and SSRIs increasing these risks
What should the nurse do if a patient’s lithium level is 2 mEq/L?
Answer: Hold next dose of lithium
Rationale: Level of 2 mEq/L indicates toxicity; maintenance range is 0.6–1.2 mEq/L.
Why are penicillinase-resistant penicillins considered to have a narrow antimicrobial spectrum?
a) They only work against viral infections
b) They are used specifically against penicillinase-producing staphylococci
c) They cannot penetrate any bacterial cell walls
d) They are less effective than penicillin G against all bacteria
Answer: b) They are used specifically against penicillinase-producing staphylococci
Rationale: Penicillinase-resistant penicillins (nafcillin, oxacillin, and dicloxacillin) have a very narrow antimicrobial spectrum and are used only against penicillinase-producing strains of staphylococci (S. aureus and S. epidermidis). Because most strains of staphylococci produce penicillinase, these drugs are the drugs of choice for the majority of staphylococcal infections. However, they should not be used against infections caused by non-penicillinase-producing staphylococci because they are less active than penicillin G against these bacteria.
A patient with type 2 diabetes mellitus is admitted to the hospital for a suspected myocardial infarction and is scheduled to have a cardiac catheterization tomorrow. The patient takes metformin at home to manage his diabetes mellitus but that has not been ordered in the hospital. A sliding scale of insulin has been ordered. What is the rationale for this change?
a) The cardiac catheterization uses contrast dye which can lead to acute renal failure and lactic acidosis for patients taking metformin.
b) The patient's stress level will be increased in the hospital and therefore the metformin won't be adequate to maintain the patient's blood sugar levels in a normal range.
c) A HgA1C is drawn first on all admitted patients to ensure that the appropriate medication is ordered for the management of diabetes mellitus while hospitalized.
d) The patient will be made "NPO" for the procedure and therefore can't take the oral metformin dose.
Answer: A
Rationale: There is a contraindication with IV contrast dye and metformin. The drug should be stopped ideally 1-2 days before IV contrast dye testing and then for 48 hours post-test. The risk is ARF, which can lead to lactic acidosis.
A nurse is preparing to administer clindamycin 900 mg by intermittent IV bolus over 30 min. Available is clindamycin 900 mg in 100 mL dextrose 5% (D5W). The nurse should set the IV pump to deliver how many mL/hr? (Round the answer to the nearest whole number. Use a leading zero if it applies. Do not use a trailing zero.)
200 mL/hr
Correct Answer Rationale:
Follow these steps to calculate the infusion rate using the Ratio and Proportion method of calculation:
Step 1: What is the unit of measurement the nurse should calculate? mL/hr
Step 2: What is the volume the nurse should infuse? 100 mL
Step 3: What is the total infusion time? 30 min
Step 4: Should the nurse convert the units of measurement? Yes (min does not equal hr)
60 min30 min = 1 hrX hr
X hr = 0.5 hr
Step 5: Set up an equation and solve for X.
Volume (mL)X mL/hr = Time (hr)
100 mLX mL/hr = 0.5 hr
X mL/hr = 200 mL/hr
Step 6: Round if necessary.
Step 7: Reassess to determine if the amount to administer makes sense. If the prescription reads clindamycin 900 mg in 100 mL D5W IV to infuse over 30 min, it makes sense to administer 200 mL/hr. The nurse should set the IV pump to deliver clindamycin 900 mg in 100 mL amount prescribed is 100 mL D5W IV at 200 mL/hr.
What are at least three common adverse effects of phenelzine?
Answer: CNS stimulation, orthostatic hypotension**, hypertensive crisis, severe hypertension, headache, nausea, increased heart rate, and increased blood pressure, increased effects of sympathomimetic drugs, serotonin syndrome when combined with SSRIs
What are two important lab values that should be monitored for patients on lithium therapy?
Answer: Monitor lithium and sodium levels
Rationale: Lithium and sodium balance affects drug excretion and toxicity risk.
A nurse understands the increased risk of adverse drug reactions in the elderly. Which of the following increases the risk of adverse drug reactions in the elderly?
a) Long-term management by the primary care provider
b) High serum albumin levels
c) Multiple pathologies
d) Subtherapeutic drug levels
Answer: C
The elderly tend to have more pathologies and greater severity of illness, which requires the use of a greater number of medications.
What patient teaching is critical in a young patient with Parkinson's disease who is starting pramipexole drug therapy to ensure safety?
a) Don't take this medication with NSAIDS due to the increased risk of gastrointestinal bleeding.
b) Sleep attacks may occur without warning and may cause harm if they occur while driving or engaging in other activities that require alertness.
c) This medication is highly teratogenic and therefore contraception strategies are recommended.
d) This medication interacts with grapefruit and/or grapefruit juice so avoiding any consumption is critical.
Answer: B
Pramipexole is a dopamine agonist that is used most often with younger patients with Parkinson's disease. Daytime somnolence and particularly sleep attacks are side effects and can be dangerous. Patient teaching is key. Pramipexole does not interact with NSAIDS, or grapefruit juice and is not a known teratogenic medication.
A nurse is preparing to administer 0.9% sodium chloride 1,200 mL IV to infuse over 24 hr. The drop factor of the manual IV tubing is 15 gtt/mL. The nurse should set the manual IV infusion to deliver how many gtt/min? (Round the answer to the nearest whole number. Use a leading zero if it applies. Do not use a trailing zero.)
13 gtt/min
Correct Answer Rationale:
Follow these steps to calculate the infusion rate using the Ratio and Proportion method of calculation:
Step 1: What is the unit of measurement the nurse should calculate? gtt/min
Step 2: What is the volume the nurse should infuse? 1,200 mL
Step 3: What is the total infusion time? 24 hr
Step 4: Should the nurse convert the units of measurement? Yes (hr does not equal min)
1 hr24 hr = 60 minX min
X min = 1,440 min
Step 5: Set up an equation and solve for X.
Volume (mL)X gtt/min = × Drop factor (gtt/mL)Time (min)
1,200 mL15 gttX gtt/min = × 1,440 min1 mL
X gtt/min = 12.5 gtt/min
Step 6: Round if necessary. 12.5 = 13 gtt/min
Step 7: Reassess to determine whether the amount to administer makes sense. If the provider prescribed 1,200 mL to infuse over 24 hr, it makes sense to administer 13 gtt/min. The nurse should set the manual IV infusion to deliver 0.9% sodium chloride IV at 13 gtt/min.
Which prototype drug is an MAOI?
Answer: Phenelzine
Rationale: Phenelzine is a classic MAOI used for depression.
What are early indications of lithium toxicity?
Answer: Coarse tremors, confusion, and GI upse, sedation
Rationale: A key sign of lithium toxicity is confusion, coarse tremors, and GI upset.
A nurse is admitting a client following acetaminophen toxicity. Which of the following medications should the nurse expect to administer to this client?
a) Acetylcysteine
b) Pegfilgrastim
c) Misoprostol
d) Naltrexone
Answer: A
Administer acetylcysteine, which is the antidote for acetaminophen.
A patient admitted in diabetic ketoacidosis is started on a continuous insulin infusion (drip). Which insulin type does the nurse expect to be prepared by pharmacy for this infusion due to cost and common utilization?
a) regular insulin
b) NPH insulin
c) insulin glargine (U-100)
d) insulin aspart
Answer: A
Regular insulin is most commonly used for a continuous insulin infusion. Rapid-acting insulin, such as aspart, can be used, but it is more expensive; therefore, regular insulin is the standard of practice.
A nurse is preparing to administer moxifloxacin 400 mg by intermittent IV bolus over 60 min. Available is moxifloxacin 400 mg in 250 mL dextrose 5% (D5W). The drop factor of the manual IV tubing is 15 gtt/mL. The nurse should set the manual IV infusion to deliver how many gtt/min? (Round the answer to the nearest whole number. Use a leading zero if it applies. Do not use a trailing zero.)
63 gtt/min
Correct Answer Rationale:
Follow these steps to calculate the infusion rate using the Ratio and Proportion or Desired Over Have method of calculation:
Step 1: What is the unit of measurement the nurse should calculate? gtt/min
Step 2: What is the volume the nurse should infuse? 250 mL
Step 3: What is the total infusion time? 60 min
Step 4: Should the nurse convert the units of measurement? No
Step 5: Set up an equation and solve for X.
Volume (mL)X gtt/min = × Drop factor (gtt/mL)Time (min)
250 mL15 gttX gtt/min = × 60 min1 mL
X gtt/min = 62.5 gtt/min
Step 6: Round if necessary. 62.5 = 63 gtt/min
Step 7: Reassess to determine whether the amount to administer makes sense. If the prescription reads moxifloxacin 400 mg in 250 mL D5W IV to infuse over 60 min, it makes sense to administer 63 gtt/min. The nurse should set the manual IV infusion to deliver moxifloxacin 400 mg in 250 mL D5W IV at 63 gtt/min.
What should the nurse ask a patient on phenelzine with severe hypertension?
Answer: Ask about foods eaten that day Rationale: To identify tyramine intake causing hypertensive crisis.
Provide at least three side effects of carbamazepine.
CNS effects: nystagmus, double vision, vertigo, staggering gait, headache à start low and slow, give at bedtime à CNS effects subside within a few weeks
Blood dyscrasis: leukopenia, anemia, thrombocytopenia à check CBC/platelets à look for bruising/bleeding gums
Teratogenesis: Avoid in use in pregnancy
Hypo-osmolarity: promotes ADH secretion à inhibits water excretion à HF at risk for fluid overload. Monitor sodium levels, edema, I&Os, HTN
Skin disorders: dermatitis, rash, Stevens-Johnson syndrome (life threatening), treat with anti-inflammatory/antihistamine meds
Hepatotoxicity: anorexia, N/V, fatigue, abdominal pain, jaundice, check baseline liver function
When providing a medication, if the nurse wants to select the route that ensures the greatest bioavailability, the route is:
a) orally
b) intravenously
c) intramuscularly
d) subcutaneously
Answer: C
The intravenous (IV) route is immediately available for distribution and action. It gets to the target tissues faster to exert its action.
A patient received atropine intravenously before surgery. The recovery room nurse notes that the patient is delirious upon awakening and has a heart rate of 96 beats/min, a respiratory rate of 22 breaths/min, and a blood pressure of 110/78 mm Hg. The nurse notifies the anesthesiologist, who will order:
a) an antipsychotic medication to treat the patient’s central nervous system symptoms.
b) activated charcoal to minimize intestinal absorption of the antimuscarinic agent.
c) ipratropium bromide to counter the respiratory effects of the antimuscarinic agent.
d) an acetylcholinesterase inhibitor to compete with the antimuscarinic agent at receptors.
Answer: D
This patient is showing signs of antimuscarinic toxicity caused by the atropine given during surgery. The most effective antidote is physostigmine, which inhibits acetylcholinesterase, allowing acetylcholine to build up at cholinergic junctions and compete with the antimuscarinic agent for receptor binding. Activated charcoal is useful only if an antimuscarinic agent has been ingested because it impedes absorption from the GI tract. Because this patient’s psychotic symptoms are caused by an antimuscarinic agent, physostigmine should be given to treat the cause; an antipsychotic medication would only treat the symptom. Ipratropium bromide is an antimuscarinic agent and would only compound the effects. This patient’s respiratory rate is only mildly elevated.