Prescription Writing
Lab Lecture
Prescription
• The prescriber’s written order to prepare or dispense a
specific treatment (usually a medication) for a specific
patient
• Who can write a prescription?
• Physician
• Dentist
• Veterinarian
• Nurses are authorized to administer medications
• Pharmacists are authorized to prepare and dispense drugs
Definition of terms
• Generic name or International Non-proprietory
Name (INN) – the scientifically and internationally
recognized name for their active ingredient/s
• Drug product – finished product containing the
active ingredient, may also contain inactive
ingredients
• Fixed Dose Combination (FDC) – containing 2 or
more active ingredients
Rational Prescription Writing
1.
Make a specific diagnosis
2.
Consider the pathophysiologic implications of the diagnosis
3.
Select a specific therapeutic objective or goal.
4.
Select a drug of choice
5.
Determine the appropriate dosing regimen
6.
Devise a plan for monitoring the drug’s action and side efects
and determine end point for therapy
7.
Plan a program of patient education.
Rational Prescription Writing
• Rule of Right
• Right drug, for the right patient, with the right diagnosis, at the
right dose, right route, right intervals, right duration of therapy
under prevailing constraints
• SANE Criteria:
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Safety
Affordability
Need
Efficacy
• Choose drugs that are clearly needed and scientifically proven
to be effective
• Do not be influenced by patient pressure or med rep pressure
Elements of a prescription
1. Identity of the prescriber
a.
b.
c.
Full name, address and contact number on top
License number, PTR, S2 number
Signature
2. Identity of the patient
a.
b.
Full name, age, address, sex (weight – optional)
Date
3. Body of the prescription
a.
b.
c.
d.
Superscription
Inscription
Subscription and Refill information
Transcription
Elements of a prescription
3. Body of the prescription
a. Superscription = Rx = “take thou”
b. Inscription
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Name of medication (generic and brand)
Strength and and dosage to be dispensed
c. Subscription and refill information
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Instruction to pharmacist for quantity of medication
Refill or not
d. Transcription = sig. = “label”
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Directions for use: route, interval, duration, purpose
Other instructions
Why Generic?
• Every generic drug product should be as satisfactory
as the trade-named product
• Generic drugs have the same bioavailability
• Bioequivalent to a reference standard formulation
• These drugs must have the same rate and extent of
absorption
• Should not differ between manufacturers
• Generic names allow substitution of medicines by
the pharmacist
• Due to unavailability, cost, etc.
Why Generic?
• Generic names
• Of distinct sound and spelling
• Grouped or related drugs may have similar prefixes of
suffixes to easily identify their class
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-ac = anti-inflammatory agents/NSAIDS
Cef- = cephalosporins
-cillin = penicillin group
-dipine = calcium channel blockers
-olol = beta blockers
-tidine = H2 antagonists (antacids)
-pril = ACE inhibitors
Prescribing errors
• Must be legible, unambiguous, dated and signed
• Should contain sufficient information to permit the
pharmacist or nurse to discover possible errors
before the drug is dispensed or administered
Prescribing errors
• Omission of information
• Continue pre-operative medicines
• Continue eye drops
• Poor prescription writing
• Poor handwriting
• Misplaced decimal point
• Abbreviations that may be misread
• Ex. 10U or 10μg may be read as 100
• Does the abbreviation OD mean once a day or right eye?
Prescribing errors
• Inappropriate drug prescriptions
• Failure to recognize contraindications imposed by
other diseases the patient may have
• Failure to obtain information about other drugs the
patient is taking (ex. drug-drug interactions)
• Failure to recognize possible psychochemical
incompatibilities between drugs (ex. disulfiram and
alcohol)
Compliance
• The extent to which patients follow treatment
instructions (adherence)
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Fail to buy/obtain the medication
Fail to take the medication as prescribed
Prematurely discontinues the medication
Patient or another person takes medication
inappropriately (ex. sharing of meds)
Off labeled use of drugs
• Not the actual intention of the drug, but may seem
to be beneficial in some cases
• Ex. Finasteride = initially a medicine for BPH, now a
medicine for hair loss
Pediatric Dosing
• Suspensions or syrups or drops
• Calculated based on weight
• Dose recommendations based on weight
• Ex. paracetamol: 10-15mg/kg/dose, given every 4 hours
• Ex. amoxicillin: 30-40mg/kg/day divided into 3 doses
• Dose recommendations based on age and average weight
• Decongestants: phenylpropanolamine or phenylephrine
• 2-6 years = 2.5mL QID
• 7-12 years = 5mL QID
• Cetirizne
• 6months-2 years: 2.5mg/day
• 2 years -5 years: 5mg/day or 2.5mg BID
Case 1
• S> An 18 year old student came to the clinic due to
nasal congestion, slightly productive cough x 2 days.
No fever. No vomiting. No pain. Able to eat well.
Slight discomfort during sleeping
• O> Pertinent PE: Temp: 36.8C, not in distress.
boggy turbinates, slightly hyperemic pharynx, clear
breath sounds.
• A>
• P>
Case 1
• Available drugs
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Decolgen
Sinutab
Neozep
Bioflu
Solmux
Mucosolvan
Ventolin nebulizer
Benadryl expectorant
Case 2
• S> 6 year old male, came to you for fever and sore throat
for 3 days duration. Decreased appetite, no vomiting or
diarrhea. No cough or colds. No other complaints.
Mother says her son has G6PD deficiency
• O> Weight = 20kg, Temp = 38.5C, not in distress.
Normal nose and ears. Hyperemic tonsils with exudates.
Clear breath sounds and heart sounds.
• A>
• P>
Case 2
• Available antibiotics
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Amoxicillin
Co-amoxiclav
Chloramphenicol
Co-trimoxazole
Metronidazole