Principles of Prescription Writing Dr Sasan Zaeri Pharm

Principles of Prescription Writing Dr Sasan Zaeri (Pharm. D, Ph. D) Department of Pharmacology

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 2

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

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

Types of Prescriptions (cont’d) n 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. n e. g. , pediatric, geriatric 5

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

Prescription Formatting n Heading n Body n Closing 7

Sample Prescription- 8

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

Prescription Formatting n Body 1. 2. 3. 4. 5. 6. The Rx symbol Drug dosage form Drug name Dose size or concentration Quantity to be dispensed (#) Directions to the patient 10

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

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

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

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

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

Contents of the Prescription n Strength of the drug n Decimal points n Avoid trailing zeros EX. 5 mg vs. 5. 0 mg; can be mistaken for 50 mg n Always use leading zeros. EX. 0. 8 ml vs. . 8 ml; can be mistaken for 8 ml 16

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Contents of the Prescription n n 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) 19

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

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

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

List of dangerous abbreviations, acronyms, and symbols Abbreviation 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, MSO 4, Mg. SO 4 Confused for one another Write “morphine sulfate” or “magnesium sulfate” 25

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Rules for writing amount of drug: n Quantities of 1 gram or more should be written in grams. n n Ex - write 2 g Quantities less than 1 gram but more than 1 milligram should be written in Milligrams For n e. g, write 100 mg, not 0. 1 g 28

n n Quantities less than 1 milligram should be written in microgram DO NOT abbreviate micrograms n eg. write 100 micrograms, not 0. 1 mg, nor 100 mcg, nor 100 μg 29

Prescription Formatting n Heading n Body n Closing 30

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

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

Sample Prescription- 33

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

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

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 36

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

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