Study Notes on Prescription and Interpretation

PCY 201: The Prescription and Interpretation of Prescriptions

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Instructor: Pharm. Mary Ugochinyere Obila

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Outline

• Definition of Prescription

• Parts of a Prescription

• Common Latin Terms Used in Prescription

• Handling of Prescription

• Errors in Prescription

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Definition of Prescription

A prescription is defined as a written order from a registered medical practitioner, which includes doctors, physicians, or other licensed practitioners such as dentists and veterinarians, directed to a pharmacist to compound and dispense a specific medication for a patient.

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Parts of a Prescription

The prescription comprises several essential components:

1. Date

2. Name, age, sex, and address of the patient

3. Superscription

4. Inscription

5. Subscription

6. Signatura

7. Renewal instructions

8. Signature, address, and registration number of the prescriber

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Date

• Every prescription must include a date.

• This date helps the pharmacist track:

  • The date the prescription was written.

  • The date when the prescription is presented for filling.

• Maintaining a chronological record assists pharmacists and physicians in referring to old cases in future scenarios.

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Name, Age, Sex and Address of the Patient

• The complete name, age, sex, and address of the patient must be clearly written on the prescription.

• The name is crucial for the pharmacist to correctly identify the patient and ensure the medication is given only to the intended recipient. Full names should be provided rather than nicknames.

• Age is particularly important for pediatric and geriatric patients since drug dosages may vary significantly based on the patient’s ability to metabolize drugs.

• Weight and height may also be required in certain cases.

• The sex/gender plays a significant role in determining drug dosage, as dosing may differ based on gender.

• The address is often recorded for contact purposes if needed.

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Weight and Height Considerations

In some cases, patient weight and height are also recorded on prescriptions, further indicating that sex/gender influences dosing decisions in medications.

• The address allows for potential follow-up with the patient regarding their treatment.

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Superscription

• The superscription is represented by the symbol “Rx.”

• This symbol is an abbreviation for the Latin phrase “Take Thou,” indicating that the patient should take the medication as prescribed.

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Inscription

• The inscription is regarded as the main part of the prescription order.

• It contains the names and quantities of the specific ingredients being prescribed.

• Each ingredient's name is written separately along with its respective quantity.

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Subscription

• This section provides directions from the prescriber to the pharmacist regarding the type of dosage form to be compounded and the number of doses to be dispensed.

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Signatura

• The signatura includes directions for the patient on how to administer the prescribed drug effectively.

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Refill/Renewal Instructions

• This section specifies whether the prescription can be renewed or not.

• It should include details such as the number of times the prescription can be renewed.

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Signature, Address, and Registration Number of the Prescriber

• The prescriber’s signature and registration number are essential to validate the prescription, making it a legal and authentic order for the pharmacist.

• The registration number is particularly important for prescriptions that involve narcotic drugs, preventing potential misuse.

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Common Latin Terms Used in Prescription

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More Common Latin Terms Used in Prescription

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Handling of Prescription

The steps involved in the handling of a prescription prior to compounding and dispensing include:

1. Receiving

2. Reading and checking

3. Collecting and weighing the materials

4. Compounding, labeling, and packaging

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Receiving

• Prescriptions must be received by the pharmacist.

• It is vital that the pharmacist maintains a neutral expression to avoid conveying any surprise or confusion upon reviewing the prescription.

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Reading and Checking

• Upon receipt of the prescription, the pharmacist must verify that it is formatted correctly.

• Screen the prescription behind the counter for privacy.

• If there are any uncertainties regarding ingredients, dosages, or instructions, the pharmacist should consult with another senior pharmacist or physician instead of discussing it with the patient directly.

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What to Check in a Prescription

When evaluating a prescription, pharmacists should check for:

• Errors in dosage

• Wrong drug prescriptions

• Contraindicated drugs

• Potential drug interactions

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Collecting and Weighing the Materials

• Prior to compounding, all materials required for the prescription should be gathered on the left side of the balance.

• After weighing, each component must be moved to the right side of the balance.

• The stock bottle label must be read at minimum three times to minimize errors:

  • When taken from the shelf

  • At the time of weighing

  • When returning containers back to their proper storage location

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Compounding, Labeling, and Packaging

• Compounding should take place in a clean, tidy environment.

• All necessary equipment must be washed and thoroughly dried before use.

• Only one prescription should be compounded at any given time to prevent mix-ups.

• The compounded materials should be stored in a suitable container, appropriate for both quantity and intended use.

• The label size should correspond proportionately to the size of the container, containing all necessary directions for patient administration.

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Errors in Prescription

Pharmacists should be wary of several common errors in prescriptions, including:

• Abbreviations

• Incorrect drug name

• Inaccurate strength of the preparation

• Wrong dosage form

• Incorrect dose

• Ambiguous instructions for patients

• Incompatibilities of drugs

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Errors Related to Abbreviations

• Abbreviations can create significant misunderstandings in interpreting prescriptions.

• Pharmacists should exercise extreme caution when deciphering ambiguous abbreviations and avoid guessing their meanings.

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Errors Related to Drug Name

• Certain medications have names that may be easily mistaken for other drugs, examples include:

  • Prednisone and Prednisolone

  • Digoxin and Digitoxin

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Strength of the Preparation

• The prescriber must specify the strength of the medication.

• This specification is crucial, especially when multiple strengths are marketed for a single product.

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Dosage Form of the Drug Prescribed

• Many medications come in various dosage forms, including liquid, tablet, and capsule formulations.

• The pharmaceutical dosage form must be explicitly mentioned on the prescription.

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Dose

• It is imperative to discuss unusually high or low doses with the prescriber to ensure patient safety.

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Instructions for Patients

• Clear instructions regarding the drug's quantity, frequency, timing, and route of administration should be explicitly noted on the prescription to prevent confusion.

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Incompatibilities

• Pharmacists must confirm there are no pharmaceutical or therapeutic incompatibilities with the prescribed medication and ensure that multiple drugs prescribed for the same patient do not interact negatively or harm the patient.