Practical Phramacolgy

Principles of Prescription Writing

Definition
is the prescriber’s order to prepare or dispense a specific treatment ---- usually medication ---- for a specific patientA written direction for the preparation & administration of a remedy

History

Prescriptions have been in use since ancient timesLatin adopted as standard language“Rx” = prescription(take thou)

Aim of 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


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

* Steps

Prescription writing
Make a Specific diagnosis
Consider the Pathophysiological implications of the diagnosis
Select a specific therapeutic objective
Select a drug of choice
Determine the appropriate dosing regimen
Devise a plan for monitoring the drug’s action & determine an end point for therapy Plan a program of patient education

* Elements

Outpatient Prescription
Prescriber’s office information Name License classification (Professional degree) Adress Office telephone numbers

A prescription should begin with the

1- name of the person for whom it is designed2- the date on which it is written. Then 3- follows the Latin word Recipe, usually abbreviated by the sign Rx, and signifying "Take," or "Take thou;“4- the names and quantities of the ingredient to be used, which are also expressed in Latin; then the directions to the compounder, followed by the directions to the patient5- finally the signature of the prescriber

prescription then has four component parts

1-SUPERSCRIPTION—which consists of the name of the patient for whom it is designed, the date, and the sign Rx—signifying "Take thou."

2-INSCRIPTION,—the body of the prescription, consisting of one or more of the following subdivisions, Basis,—or chief ingredientAdjuvant,—to assist the action of the basis.Corrective,—to correct some injurious quality of the other ingredients.Vehicle or excipient ,—to give it a suitable form.

SUBSCRIPTION,—the directions for the compounder, usually expressed in contracted Latin.SIGNATURE,—the instructions for the administration of the medicine, in English or Latin, followed by the signature of the prescriber.

* Outpatient Prescription

Prescriber’s name license classification (Professional degree) Adress Office telephone numbers Prescriber’s office information Patients information
Patient’s name Date
Address
REFILL TIMES
OR UNTIL
NO CHILD PROOF CONTAINER
Drug name and strength Quantity SIG:
WARNING
PRESCIBER’S SIGNATURE Presciber’s other identification data Date
Inscription & Subscription
Superscription
Signatura
Superscription

Prescription Formatting

Heading Body Closing

Current Prescription Formatting

Heading Name, address, and telephone number of the prescriber sex and age of the patient Date of the prescription
3

Contents of the Prescription

Patient Name and AddressFull first and last nameMiddle initial may be helpfulDOB – not required, but will be helpful in further identifying the correct patient to prevent medication errors

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

Contents of the Prescription

Selecting the drug Medication Allergies Availability Cost



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

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

Current Prescription Formatting

ClosingPrescriber’s signatureRefill instructionsGeneric substitution instructions 5

* Prescription writing

Abbreviation
Meaning
tab
tablet
cap
capsule
PO
by mouth
PR
per rectum
SL
sublingual
IM
intramuscular
IV
intravenous
SC, SQ
subcutaneous
Abbreviation
Meaning
OTC
over-the-counter
pc
after meals
ac
before meals
prn
when needed
q
every
q6h
every 6 hours
qhs
every night at bed time
stat
at once

List of abbreviations

Tablets - tab Capsule– cap Syrup – syr Suspension – susp Injection – InjMetered dose inhaler – as such Lotion – as such

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

Dosing count ;

Weight – based dosing Always convert patient weight to correct units (kg)Liquid medicationsOne product may be available in a number of concentrationsBe familiar with various product concentrationsIndicate BOTH concentration and dose of medicationExample: Cephalexin suspension 125 mg/ 5 ml 1 teaspoon/ every 8 h

* Prescribing errors

Error
Misread (Danger)
Correct
.1
1
0.1
1.0
10
1
/
1
Abandoned
10U
100
10 units
IU
10 or 14


mg
mcg
Poor presciption writing
Other errors
Use leading zeros
Never use trailing zeros

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

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

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


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 EX. write 100 micrograms, not 0.1 mg, nor 100 mcg, nor 100 μgUse ml or mL for milliliters


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

Contents of the Prescription

Directions for useWrite out in full English or use Latin abbreviations Latin abbreviations – more convenient, more potential for mistakes Avoid Dangerous Abbreviations Provide clear and specific directions

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

DOCTOR’S ORDER SHEER 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
1



2


3


4


5


6


7


8



9


10


11


12


13


14


15

Sample Prescription-

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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

* Controlled Substance Schedules

Schedule I Examples: heroin 1. Potential for abuse ---- High 2. No accepted medical use or lacks accepted safety May be used for research purposes by properly registered individuals.

* Controlled Substance Schedules

Schedule II Examples: morphine 1. Potential for abuse ---- High. 2. Has a currently accepted medical use 3. Abuse may lead to severe psychological or physical dependence.

* Controlled Substance Schedules

Schedule III Examples: anabolic steroids 1. Abuse potential less than substances in schedule I or schedule II. 2. Has a currently accepted medical use. 3. Abuse may lead to moderate or low physical dependence or high psychological dependence.

* Controlled Substance Schedules

Schedule IV Examples: Alprazolam 1. Abuse potential less than substances in schedule III. 2. Has a currently accepted medical use 3. Abuse may lead to limited physical or psychological dependence relative to substances in schedule III.

* Controlled Substance Schedules

Schedule V Examples: phenobarbital 1. Low potential for abuse relative to schedule IV. 2. Has a currently accepted medical use

3. Some schedule V products may be sold in limited amounts without a prescription at the discretion of the pharmacist; however, if a physician wishes a patient to receive one of these products, it is preferable to provide a prescription 4. Limited dependence possible

* Controlled Substance

- All prescriptions must be written in ink; this practice is compulsory for schedule II drugs- Date- Prescriber’s name & address- Patient’s name, age, & address- Diagnosis- No abbreviations- All doses, number of ampules, tablets, etc. should be written in words (letters) & in figures (numbers) - Prescriber’s signature- Prescription is dispensed once, & is kept by pharmacist

* -Refill - Refill prn (refill as needed) --- is not appropriate - If no refill is desired, “Zero” (not 0) --- should be written in the refill space - For schedule II drug ---- no refill - For schedule III &IV drug ---- not to exceed 5 refills or 6 months after the issue date, whichever comes first- For schedule V drug ---- no restriction

Dose units

dose units can be misinterpreted. This is especiallyimportant in paediatrics and for drugs where there is a wide variation in the dose thatcan be administered e.g. opiates• A patient died after receiving an epidural infusion containing 30mg diamorphine in 10mls instead of 3mg in 10mls. The doctor's prescription had been misread.July 3 1996)

Write the word units in full

• Abbreviation of the word units to IU resulted in the administration of 10-foldoverdoses of insulin when prescriptions for 6IU were misread as 61 units (PharmJ 2001;267:193)


avoiding the need for decimal points wherever
possible. Milligram to microgram conversions can result in 10-fold errors.• A baby weighing 3.2kg was prescribed 10micrograms/kg of digoxin. When the prescription was written the decimal point was omitted and a dose of 320microgram was prescribed and administered.

Write up the following doses in micrograms Digoxin 0.0625mg. Thyroxine 0.05mg Clonazepam 0.1mg Ipratropium inhaler 0.02mg per dose Atropine 0.6mg

CASE #2

A hypertensive patient accidentally received Vantin 200 mg instead of Vasotec 20 mg when a pharmacist misread this prescription

Prescribing errors

commonly involve incorrect doses, illegible details ordering inappropriate medications drugs that may react with other medications already being taken

for example

if a doctor fails to prescribe an antihypertensive drug for someone who could benefit from it. if a doctor to prescribe bacteriostatic with bactericidal Allergy: diagnosis and treatment of allergic conditions

SUMMARY

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.


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

Model Prescription Name: ABC 2) Date: 31.07.07 3) Age: 70yrs. 4) 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. 34523