KV, an employee at a large manufacturing facility, is recovering
from an industrial accident. The accident, which occurred 4
months ago, was caused by KV's inability to operate the
machinery due to heroin intoxication.
Before returning to work, KV must be evaluated by the company
physician. When the employee presents to the physician's
office, the physician notes that KV's pupils are pinpoint.
The physician also notes a laceration on KV's left arm. The
physician is concerned that KV is still abusing heroin, but she
denies taking any drugs other than the "painkillers" prescribed
for her injury. She presents a bottle of long-acting morphine
tablets to corroborate her story.
The physician decides to order a urine drug screen before
approving KV's return to work. The drug screen proves positive
for morphine, codeine, and 6-acetylmorphine.
Should the physician believe KV's claim of using only the prescribed
DK, a 59-year-old man, was admitted to the local hospital
with a chief complaint of palpitations and occasional dizziness.
He has a history of asthma, diabetes, and hypertension. His
current medications include glyburide, nifedipine, chlorthalidone,
On admission, EKG monitoring revealed atrial fibrillation
with a ventricular rate of 165 beats/minute. DK was given 0.5
mg of digoxin intravenously. Six hours later, he was given 0.25
mg of digoxin intravenously. After the second dose, his ventricular
rate decreased to 100 beats/minute.
Two hours after the second dose, a digoxin level was
obtained. The level was reported as 4.2 ng/mL. Because the
digoxin level was elevated, subsequent intravenous doses
Prior to discharge, DK was started on oral digoxin dosed at
0.25 mg daily. He also was started on potassium supplementation
because his serum potassium level was 3.0 mEq/L.
A few days later, DK returned to the hospital with symptomatic
atrial fibrillation. His ventricular rate was 175 beats/
minute. DK denied consuming caffeine or taking theophylline.
He had not started any other new medications since being discharged
from the hospital earlier in the week, and he did not
appear dehydrated. His serum creatinine was 0.9 mg/dL, and
his potassium level was 4.2 mEq/L. His digoxin level, tested 6
hours after his dose, was 1.3 ng/mL.
The medical resident in the emergency room asked the
pharmacist for assistance in explaining why DK's digoxin level
had declined enough to allow his atrial fibrillation to break
through. The pharmacist explained that the initial level was
assessed prior to the completion of the distribution phase.
Therefore, equilibrium had not been reached between the
serum and tissues. Also, the drug had not reached steady
state because DK had received only 2 doses of digoxin.
The resident wonders whether the potassium levels played
a role in DK's response to the digoxin. Can the potassium levels
have played a role?
Click Here For The Answer ----------->
No, the physician should not believe KV's claim. Although morphine and codeine should be present in KV's urine due to her prescription
morphine, 6-acetylmorphine should not be present. The presence of 6-acetylmorphine is indicative of heroin use.
CaseTwoThe pharmacist should explain that the low potassium levels at the initiation of digoxin therapy allowed for a more intenseresponse than expected. Once the potassium level returned to normal, the digoxin level of 1.3 ng/mL was inadequate to control DK'sventricular rate.