PRN Medications
Indications & Use
Inpatient Medicine Core Curriculum
Bindu Swaroop, MD
VA Long Beach Health Care System
Objectives
• Identify which prn medications are
appropriate for inclusion in admission orders
• Identify contraindications and adverse effects
associated with common prn medications
• Known when to evaluate the patient prior to
ordering or the nurse giving a prn medication
Common Uses
•
•
•
•
•
•
Sleep
Pain
Cardiovascular: Hypertension
Sedatives: ETOH withdrawal, agitation
Pulmonary: Nebulizers, Mucolytics
GI: Bowels, Heartburn
Case Vignette
HPI: 59 year old male admitted for chest pain
and acute ETOH intoxication. He also complains
of hematemesis during his most recent drinking
binge.
PMHx: AVNRT, Hepatitis C, insomnia, depression
and COPD
Outpatient medications: combivent inhaler bid,
ibuprofen 600mg po tid prn
Case Vignette
• EKG on admission reveals AVNRT @111 bpm
He is admitted to the medicine service with the
following prn orders:
-Ativan 2mg IVP q5min prn seizures
-Ativan 2mg po q4hr prn withdrawal
-Albuterol neb q6h prn, Atrovent neb q6hr prn
-Acetaminophen 650mg q4hr prn pain
-Ibuprofen 600mg po tid prn pain
Do you see any problems with these orders?
Case Vignette
That night the patient subsequently requests pain medication for
his chest pain. It is determined by the night float that there is no
evidence of ACS. Since ibuprofen is ordered prn the night float
instructs the nurse to give this to the patient. The patient still
complains of pain later that night, and the night float writes an
order for Morphine sulfate 2mg IVP q4hr prn pain.
2. Are these appropriate meds to give to the patient?
3. What other alternatives could have been given?
Analgesics
NonOpiods
Opiods
Oral
Pain Severity
SC/IM/IV
Pain Severity Adverse Effects
Acetaminophen
325-650mg
Mild
Ketorolac
30-60mg
Moderate
Ibuprofen
600-800mg
Mild
Tramadol
50-100mg
Mild to
Moderate
Tylenol w/
codeine
30mg-60mg
Mild to
Moderate
Morphine
Moderate to
Severe
Constipation,
Ileus, n/v,
respiratory
depression,
urinary retention
Vicodin
(5mg/500mg)
Moderate
Dilaudid
Severe
Caution Hepatic
or Renal
Impairment
Percocet
(5mg/325mg)
Moderate
Fentanyl (IV or
patch)
Severe
Caution in
hepatic or renal
impairment
PUD, GI bleed,
renal toxicity
Case Vignette
The next day his BP has risen to 170/105. He is given hydralazine
10mg IVP by the team with a drop in his BP to 125/78.
3. What is likely contributing to the rise in BP?
4. What side effects could occur from lowering the BP too much?
5. How else could this patient have been treated?
Hypertension
• Goal:
-To identify and treat the underlying cause
-Prevent end-organ damage
• Common Causes:
Rebound
Inadequate dosing
Drug Interactions
ETOH withdrawal
Hypoxemia, respiratory distress
Pain, Anxiety
Autonomic response: urinary retention, constipation, SCI
Hypertension
Approach to evaluating the patient:
-Determine patient’s baseline
-Confirm accuracy, both arms, cuff size
-Screen for underlying cause
-Determine if hypertensive emergency or
urgency is present
Hypertension
Treatment:
• Urgency (DBP >120 or SBP >180):
-gradual reduction of BP to 160/110 over 24-48 hours
-use ORAL meds
• Emergency (evidence of end-organ damage) :
• Immediate reduction of SBP by 15-20%
• Use PARENTERAL agents and transfer to ICU
Hypertension Clinical Pearls
• Hypertensive treatment rarely requires
immediate treatment in the middle of the
night
• Avoid prn use of rapid acting agents (can
precipitate ischemic events)
• For patients with sustained HTN, primary
team should initiate treatment with long
acting regimen
Case Vignette
• Later that night the patient requests something for sleep and
receives Benadryl 25mg po, written as qhs prn per night float.
On day three of admission he develops urinary retention with
a PVR of 300cc. A foley catheter is placed. You review his chart
and notice a prior urology note indicating the patients
prostate size on DRE is 50g.
7. What could be contributing to the urinary retention?
8. What other alternatives could have been used for his
insomnia?
Hypnotics
Benadryl
25mg-50mg
Beers high severity
Anti-cholinergic effects
(confusion, dry mouth,
urinary retention, wheezing;
caution in pts with glaucoma
and BPH
Temazepam
15-30mg
(geriatric 7.5mg)
Beers high severity
Same AE as any benzo;
contraindicated in glaucoma
caution in those with falls
risk, hepatic or renal
impairment
Trazodone (unlabeled use)
25-50mg
Okay in elderly
Hypotension, increased
bleeding risk if on NSAID’s or
warfarin, priapism, serotonin
syndrome, caution post-MI or
with h/o seizures
Ambien
5-10mg
Okay in elderly
HA, dizziness, caution in
those with respiratory
compromise, myasthenia
gravis
Case Vignette
• He remains hospitalized due to social issues
including homelessness. On day 4 of admission
you are called by the nurse due to the patient
falling in his room. You evaluate his gait and
notice he is unsteady in addition to being more
somnolent than usual.
9. What could be contributing to the fall and gait
impairment?
Sedatives
Ativan: common use in ETOH withdrawal
-AE include sedation, respiratory depression
-Caution in those with acute angle glaucoma, sleep apnea,
respiratory issues, hepatic/renal impairment, h/o drug abuse
or falls risk
-Geriatric patients no more than 3mg/day
Anti-psychotics:
Haldol (Typical), Atypical Antipsychotics
(seroquel, risperidone)
-anti-cholinergic side effects, QT prolongation
-Not for use in dementia related psychosis (increased risk of
death compared to placebo)
Case Vignette
A review of BCMA indicates the patient has continued to receive
ativan despite no further evidence of withdrawal due to
complaints of anxiety and insomnia. A review of his chart reveals
he was previously on mirtazapine but this medication had not
been continued on admission.
On review of vital signs during rounds, it is noted that the
tachycardia noted on admission is persistent despite
administration of ativan.
10. What else could be contributing to the tachycardia?
Pulmonary
• Nebulizers:
– Albuterol (max dose 3mL q4hours): can cause
tachycardia, arrhythmia, caution in patients with
ischemia
– Atrovent: anti-cholinergic side effects; caution in
those with glaucoma, BPH
• Mucolytics:
– Mucomyst: can cause bronchospasm; use 10-20
minutes after bronchodilator administration
Case Vignette
• The patient subsequently complains of
diarrhea the next day. Stool studies are sent,
and the intern orders lomotil prn for loose
stools.
11. Is this an appropriate order?
Gastrointestinal
• Heartburn: Maalox (aluminum dioxide, magnesium hydroxide)
or Maalox plus (includes simethicone)
– AE: constipation, cramps, fecal discoloration; aluminum
intoxication
– Use with caution in renal impairment: hypophosphatemia or
hypermagnesemia
– long list of drug interactions
– Must be administered one hour apart from other oral meds
• Constipation: phosphate (fleets) enema
– Do not use in patients with renal impairment, ascites, heart failure, GI
obstruction or megacolon
• Diarrhea: do not use in those with c.difficile colitis
– Loperamide (Immodium): caution in hepatic impairment
– Lomotil (diphenoxylate/atropine): anti-cholinergic side effects)
Case Vignette
• The patient subsequently does well and is discharged. Upon
discharging the patient, you order the following outpatient
medication regimen:
–
–
–
–
–
Ibuprofen 600mg po tid prn
Vicodin5/500mg 2 tabs q6hr prn
Combivent inhaler q4hr prn
Benadryl 25mg po qhs prn
Librium taper
Are these appropriate orders?
Summary
• For all PRN orders, know the correct dosage,
common adverse effects and contraindications
• Check the next day to see if your patient actually
received any of the PRN meds
• Convert frequently administered PRN meds into
standing orders
• Don’t just put in PRN orders to save night float
the “trouble” of getting called
• Evaluate underlying cause or condition requiring
use of a PRN med and treat accordingly