Principles of prescription writing Balakrishnan S

Lets introspect...... No. with Department not written 71% No. of drugs per prescription: 2.32 No. of drugs by generic: 26.8% No. of drugs by brand name: 73.2% No. with name and designation not written 80.6% No. with doses not clear 47.6% No. with duration not written 53% No. Drugs not dispensed 5.8%

What is a prescription? Drug prescription – A written or verbal order for a medication by a licensed individual(physician, dentist, veterinarian,etc)

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

Four common types of prescription: Prescriptions in general practice Hospital prescriptions for in-patients Hospital prescriptions for a non hospital pharmacy Private prescriptions

General Drug Information Proprietary vs. nonproprietary Single vs. compound Dosage

Parts of the prescription: 1) Superscription: Rx Also includes the patient details 2) Inscription: Ingredients, Quantity of each used 3)Subscription: Directions to the dispenser Directions to the patient Signature of the prescriber Date of writing the prescription

Following information must be given on a Prescription: 1)      Date 2)      Identification of the patient 3)      Formulation of the drug – eg Tablets - tab Capsule – cap Syrup – syr Suspension – susp Injection – Inj Metered dose inhaler – as such Lotion – as such

Rules for writing quantity of drug: a)Quantities of 1 gram or more should be written in grams. For example, write 2 g. b) Quantities less than 1 gram but more than 1 milligram should be written in Milligrams For eg, write 100 mg, not 0.1 g c) 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 d) If a decimal point cannot be avoided for values under 1, write a zero before it, for example write 0.5ml not .5ml

Rules for writing quantity of drug: e) Use ml or mL for milliliters f) For liquid oral medicines: The dose should be stated as the number of milligrams in either 5 ml or 10ml, Since these are readily measured amounts, & special spoons are provided to patients for the measurements.

Rules for writing quantity of drug: 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.  

Frequency of administration : Should be clearly indicated Atenolol 100mg once daily Amoxicillin 250mg t.d.s. (Accepted abbreviations may be used! BUT DO NOT USE) - Tell the patient what you mean be these times a day/ four times a day!

Route & method of administration: - should be clearly indicated. Amount to be supplied Any caution / warning

Model Prescription Name: ABC 2) Date: 31.07.07 3) Age: 70yrs. 4) Sex: male 5) Address: 20, III Cross, Eswaran koil st. Pondicherry 605 002 6) PIMS No: 0298298 7) Diagnosis: Idiopathic Parkinsonism

Model Prescription 8) Rx 9) Tab Levodopa 100mg Tab Carbidopa 25mg 10) Dispense 100 combination tablets 11) Take 2 tablets by mouth3 times daily with breakfast, lunch and dinner. Take with food. 12) Dr. Sathya MD 13) Assistant Prof. Neurology, 14) PIMS, Pondicherry 605 014 15) Ph: 0413-2207654 16) Reg. No. 34523 17) (TN medical council)

Look Alike/Sound Alike Names CASE # 1: Serzone (nefazodone) vs. Seroquel (quetiapine) (antidepressant) (antipsychotic) Similar overlapping strengths (100 mg and 200 mg) Similar dosage forms (tablets) Similar dosing interval (BID) Similar titration schedule Often stocked in close proximity on pharmacy shelf Prescribing and dispensing errors have led to a number of adverse events (N/V, hallucinations, AMS, lethargy, seizures, death)

List of dangerous abbreviations, acronyms, and symbols Potential Problem Preferred Term U (unit) Mistaken as zero, four, or cc 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” Trailing zero and lack of leading zero Decimal point missed Never write a zero by itself after a decimal point, and always use a zero before a decimal point MS, MSO4, MgSO4 Confused for one another Write “morphine sulfate” or “magnesium sulfate”

List of additional dangerous abbreviations, acronyms, and symbols ABBREVIATON POTENTIAL PROMBLEM PREFERRED TERM µg (microgram) Mistaken for mg (milligram) Write “microgram” H.S. (at bedtime or half – strength) Mistaken for either meaning: Also mistaken for every hour Write out “half – strength” or “at bedtime” T.I.W (three times a week) Mistaken for three times a day or twice weekly Write “three times weekly” or “3 times weekly” S.C. or S.Q. (subcutaneous) Mistaken for SL for sublingual or “5 every” Write “Sub-Q” or “subQ” or “subcutaneously” D/C Interpreted as discontine whatever medication follows (typically discharge meds) Write “discharge” c.c. Mistaken for U (units) when poorly written Write “ml” for milliliters A.S., A.D., A.U. (Latin abbreviations for left, right, both ears) O.S., O.D., O.U. (Latin abbreviations for left, right, both eyes) Mistaken for each other (A.S. for O.S., A.D. for O.D., A.U. for O.U., visa versa) Write out “left ear” or “right ear” or “both ears” Write out “left eye” or “right eye” or “both eyes”

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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.

DOCTOR’S ORDER SHEER Drugs 1 2 3 4 5 6 7 8 9 10 Patient’s Name: Age / Sex: PIMS No:   DOCTOR INCHARGE: No Drugs Strength Dosage freq Route Signature 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15