1. Principles of Prescription Writing
Dr Sanjeewani Fonseka
Department of Pharmacology

2. History Prescriptions have been in use since ancient times
Latin adopted as standard language
“Rx” = prescription

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. 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.

5. Writing Prescriptions Who can write a Rx?
Practitioners
Physicians, veterinarians, dentists

6. Prescription Formatting
Heading
Body
Closing

7. Current Prescription Formatting
Heading
Body
Closing

8. Current Prescription Formatting
Heading
Name, address, and telephone number of the prescriber
Name, sex and age of the patient
Date of the prescription 3

9. Contents of the Prescription
Patient Name and Address
Full first and last name
Middle initial may be helpful
DOB – not required, but will be helpful in further identifying the correct patient to prevent medication errors

10. Contents of the Prescription
Practitioner’s Name, Address, and Phone number
Validates prescription
Provides contact information to clarify any questions

11. Contents of the Prescription
Date
Date the prescription is issued or written
Allows the determination of the life of the prescription to validate refills
Ensures continual patient supervision
Promotes patient follow - up

13. Current Prescription Formatting
Heading
Body
Closing

14. Current Prescription Formatting
Body
The Rx symbol
Name
dose size or concentration (liquids) of the drug
Amount to be dispensed
Directions to the patient 4

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

16. Contents of the Prescription
Name of the drug
Multiple drugs per prescription can add to confusion
KEEP IT SIMPLE

17. Contents of the Prescription
Name of the drug - CAUTION:
Look Alike/Sound Alike drug names
Massive number of new drug releases
Massive number of reformulations
Drug marketing strategy
Build on established names
New combination drugs – Use converged names

18. Contents of the Prescription
Name of the drug
AVOID THE USE OF:
Abbreviations
Many drugs identified with abbreviations
EX: HCT for hydrochlorothiazide, MSO4 for morphine sulfate
Attempts to standardize abbreviations have been unsuccessful

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

20. Tablets - tab
Capsule – cap
Syrup – syr
Suspension – susp
Injection – Inj
Metered dose inhaler – as such
Lotion – as such

21. Contents of the Prescription
Strength of the drug
Be familiar with drugs and their various dosing strengths and dosage forms
When in doubt, use references

22. Dosing cont; Weight – based dosing
Always convert patient weight to correct units (kg)
Liquid medications
One product may be available in a number of concentrations
Be familiar with various product concentrations
Indicate BOTH concentration and dose of medication
Example: Cephalexin suspension 125 mg/ 5 ml
1 teaspoon/ every 8 h

23. 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

24. Contents of the Prescription
Quantity of the drug
Prescribe only necessary quantity
Write for specific quantities rather than time period (for example: dispense #30 vs. dispense for 1 month)
Calculate: quantity = frequency per day x treatment days
Writing out “Dispense # X” is helpful

25. Rules for writing quantity 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 eg, write 100 mg, not 0.1 g

26. Quantities less than 1 milligram should be written in micro / nano gram as appropriate.
DO NOT abbreviate micro/ nanograms; since that can lead to Prescribing errors. For eg. write 100 micrograms, not 0.1 mg, nor 100 mcg, nor 100 μg
Use ml or mL for milliliters

27. For some drugs, a maximum dose may need to be stated ( for eg
For some drugs, a maximum dose may need to be stated ( for eg. ergotamine in migraine & colchicine in gout).
Eg: Ergotamine 1 mg at onset of attack & repeat every 30 min if necessary . Do not take more than 6 mg in one day or more than 12mg in one week

28. Contents of the Prescription
Directions for use
Write out in full English or use Latin abbreviations
Latin abbreviations – more convenient, more potential for mistakes
Avoid Dangerous Abbreviations
Provide clear and specific directions

29. Should be clearly indicated
Atenolol 100mg once daily
Amoxicillin 250mg t.d.s.
- Tell the patient what you mean be these times a day/ four times a day!

31. Contents of the Prescription
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

32. Sample Prescription-

33. Contents of the Prescription
Indication
Encouraged, seldom practiced
Helps confirm appropriateness of medication
Reminds patient of drug’s purpose
Facilitates communication between health care providers

34. Prescription Formatting
Heading
Body
Closing

35. Current Prescription Formatting
Closing
Prescriber’s signature
Refill instructions
Generic substitution instructions 5

36. Contents of the Prescription
Refills
To avoid interrupting maintenance therapy, practitioners can authorize refills on a written prescription
Refills authorized are valid only for life of the prescription – 1 year

37. Controlled Substances
Definition - a prescription drug whose use and distribution is tightly controlled because of its abuse potential or risk
Regulation is more strict

38. Prescription for controlled drugs must(e.g.morphine)
Be completely written in the prescriber’s hand writing in ink
Be signed & dated
Carry the prescribers’ address
Carry the name & address of the patient
State the form of the drug
State the total quantity of the drug or the number of dose units to be disposed in both words & figures
State the exact size of each dose in both words & figure.

39. 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

40. CASE #2
A hypertensive patient accidentally received Vantin 200 mg instead of Vasotec 20 mg when a pharmacist misread this prescription

41. SUMMARY

42. MAXIMIZE PATIENT SAFETY
ALWAYS write legibly.
ALWAYS space out words and numbers to avoid confusion.
ALWAYS complete medication orders.
AVOID abbreviations.
When in doubt, ask to verify.

43. Contents of the Prescription
Date of the order
Patient Name and Address
Name of the drug
Strength of the drug
Quantity of the drug
Directions for use
Practitioner Name, Address, Telephone number

44. Model Prescription
Name: ABC ) Date:
3) Age: 70yrs ) Sex: male
Diagnosis: Idiopathic Parkinsonism Rx
9) Tab Levodopa 100mg
Tab Carbidopa 25mg
2 tablets by mouth 3 times daily for one month .
Take with food.
Dr. Sathya MD
Assistant Prof. Neurology,
Reg. No