1. Principles of Prescription Writing
Dr Sasan Zaeri
(PharmD, PhD)
Department of Pharmacology

2. Definition
A prescription is a written, verbal, or electronic order from a practitioner or designated agent to a pharmacist for a particular medication for a specific patient

3. Prescription drug
Drug that requires a prescription because it is considered potentially harmful if not used under the supervision of a licensed health care practitioner

4. Types of Prescriptions
Generic Name The nonproprietary name (based on pharmacological group)
e.g., Amoxicillin, Fluoxetine, Diazepam, Aspirin
Brand Name The proprietary name provided by pharmaceutical company who holds the patent on the drug
e.g., Prozac®, Viagra®, Xanax®

5. Types of Prescriptions (cont’d)
Compounded Requires the preparation of one or more active ingredients with one or more pharmaceutical necessities, e.g., suspending agent, flavoring agent, to create a finished product.
For example, an oral compounded prescriptions may be used to facilitate the administration of a solid dosage form that is not available in liquid form for patients unable to swallow a solid dosage form.
e.g., pediatric, geriatric

6. Types of Prescriptions (cont’d
New An original prescription order dispensed for the first time
Refill A repeat dispensing of the original prescription order

7. Prescription Formatting
Heading
Body
Closing

8. Sample Prescription-

9. Prescription Formatting
Heading
Name, address, and telephone number of the prescriber
Validates prescription
Provides contact information to clarify any questions
Name, sex and age of the patient
Age is important if for a pediatric or geriatric patient
Date of the prescription
to validate refills, to ensure pt supervision

10. Prescription Formatting
Body
The Rx symbol
Drug dosage form
Drug name
Dose size or concentration
Quantity to be dispensed (#)
Directions to the patient

11. Contents of the Prescription
Selecting the drug
Medication Allergies
Availability
Cost

12. Contents of the Prescription
Abbreviations of dosage forms
Tablets - Tab
Capsule – Tap
Syrup – Syr
Suspension – Susp
Injection – Inj
Lotion – as such
Spray- as such

13. Contents of the Prescription
Name of the drug- CAUTION:
Be very cautious about drug names that “sound/look” alike
e.g. Flagyl vs. Plasil

14. Contents of the Prescription
Name of the drug- AVOID the use of Abbreviations
DO NOT use abbreviations for drugs prescribed unless the abbreviation is official and routine:
SSKI (Saturated Solution of Potassium Iodide)
NS (Normal Saline)
NTG (Nitroglycerin)
MTX (Methotrexate)
MOM (Milk of Magnesia)

15. Contents of the Prescription
Strength of the drug
Be familiar with drugs various dosing strengths and dosage forms
When in doubt, use references
Writing no strength means prescribing the lowest available strength

16. Contents of the Prescription
Strength of the drug
Decimal points
Avoid trailing zeros
EX. 5 mg vs. 5.0 mg; can be mistaken for 50 mg
Always use leading zeros.
EX. 0.8 ml vs. .8 ml; can be mistaken for 8 ml

17. Synthroid (levothyroxine)
Avoid a tenfold overdose.
Place a zero before the
decimal point.

18. Avoid potential tenfold overdoses. Never follow drug doses with
a decimal point
and zero.
(example of dilaudid (hydromorphone)1mg
was read as 10 mg)

19. Contents of the Prescription
Quantity of the drug (#)
Avoid writing a prescription for a large quantity of drug unless it is absolutely determined that such a quantity is necessary
For chronic medication, it is better to start with a lower number at first in the event that the patient cannot tolerate it because of side effects
Economic considerations (Limitation by insurance organizations)

20. Contents of the Prescription
Quantity of the drug
Quantity (#) = frequency per day x treatment days

21. Contents of the Prescription
Directions for use
Avoid “as directed” as far as possible
Write out in full English or use Latin abbreviations

24. Contents of the Prescription
Latin abbreviations – more convenient, more potential for mistakes
Avoid Dangerous Abbreviations

25. List of dangerous abbreviations, acronyms, and symbols
Potential Problem
Preferred Term
U (unit)
Mistaken as zero, four, cc
Write “unit” ug
Mistaken as mg
Write “microgram”
IU (international unit)
Mistaken as IV or 10
Write “international unit”
Q.D
Mistaken for QID
Period after Q can be mistaken for “I”
Write “daily”
MS, MSO4, MgSO4
Confused for one another
Write “morphine sulfate” or “magnesium sulfate”

26. A handwritten "u"
can look like a zero,
a four, or "cc."
Always write out
"unit."
(all three problems
illustrated above)

27. can sometimes look like
The abbreviation "q.d."
can sometimes look like
"q.i.d." Always spell
out the word "daily."

28. Rules for writing amount of drug:
Quantities of 1 gram or more should be written in grams.
Ex - write 2 g
Quantities less than 1 gram but more than 1 milligram should be written in Milligrams For
e.g, write 100 mg, not 0.1 g

29. Quantities less than 1 milligram should be written in microgram
DO NOT abbreviate micrograms
eg. write 100 micrograms, not 0.1 mg, nor 100 mcg, nor 100 μg

30. Prescription Formatting
Heading
Body
Closing

31. Prescription Formatting
Closing
Generic substitution instructions
Refill instructions
Prescriber’s signature

32. Determine preference for brand or generic product
Brand vs. generic
Is Brand always better? NO
If practitioner prefers brand, must indicate in print, - do not substitute or brand necessary

33. Sample Prescription-

34. Contents of the Prescription
Refills
To avoid interrupting maintenance therapy
Refills “N” times or NR. Leaving this section blank implies that the prescription is non- refillable
a prescription refill for a conventional, non-controlled medication has a one year expiration time

35. MAXIMIZE PATIENT SAFETY
ALWAYS write legibly
Use the same pen for the entire prescription
If a mistake is made, e.g., number of tablets, cross out the mistake, write “error” above it, and then initial it
AVOID abbreviations
When in doubt, ask to verify

36. CASE #1
Poor handwriting contributed to a medication dispensing error that resulted in a patient with depression receiving the antianxiety agent Buspar 10 mg instead of Prozac 10 mg

37. CASE #2
A hypertensive patient accidentally received Vantin (cefpodoxime) 200 mg instead of Vasotec (enalapril) 20 mg when a pharmacist misread this prescription

38. Can you read this?
Tegretol (carbamazepine) or TEQUIN (gatifloxacin) ???