Prescriptions - parts of prescription , legality and identification of medication related problems like Drug interactions

PRESCRIPTIONS

Parts of a Prescription (Short Notes – Exam Ready)

A prescription is a written order by a registered medical practitioner to a pharmacist for dispensing medicines to a patient.

A typical prescription consists of the following parts:

1. Date

• Indicates date of prescribing and date of presentation.
• Essential for narcotic and habit-forming drugs to prevent repeated misuse.
• Helps verify prescription validity.

2. Name, Age, Sex & Address of Patient

• Helps in identification of the patient.
• Age and sex are crucial for dose calculation, especially in children and elderly.
• Missing details may be added by the pharmacist after proper enquiry.

3. Superscription (℞)

• Represented by the symbol ℞ (Rx).
• Derived from Latin word “Recipe” meaning “You take”.
• Historically believed to be derived from the sign of Jupiter, symbolizing healing.

4. Inscription

• Main body of the prescription.
• Contains:
• Names of drugs
• Strength and quantity
• Drugs may be:
• Official preparations
• Proprietary products
• Generic drugs
• Extemporaneous (individual formula)

In complex prescriptions, inscription includes:

• Base – Active therapeutic agent
• Adjuvant – Enhances action or palatability
• Vehicle – Solvent or volume enhancer

⚠️ Careful interpretation of abbreviations is essential to avoid medication errors.

👉 Nowadays, most drugs are dispensed as ready-made formulations, so compounding is rare.

5. Subscription

• Directions to the pharmacist.
• Specifies:
• Dosage form
• Quantity to dispense
• Common example: “Fiat mistura” (Make a mixture)
• Often omitted today due to ready-made formulations.

6. Signatura (Sig.)

• Directions to the patient.
• Written as “Sig”.
• Must be transferred to the dispensing label.

Includes:

• Dose
• Frequency
• Timing
• Route of administration
• Special instructions (e.g., dilution, after food)

📌 Example:

Cochleare magnum ter in die post cibos sumenda
(Take one tablespoonful three times daily after meals)

7. Renewal (Refill) Instructions

• Indicates whether the prescription can be refilled and how many times.
• Crucial for controlled drugs to prevent abuse.

8. Signature, Address & Registration Number of Prescriber

• Confirms authenticity and legality.
• Mandatory for narcotics and psychotropic substances.
• Prescription without prescriber’s signature is invalid.

Example of a Typical Prescription (Conceptual Breakdown)

• Clinic details
• Patient details
• Date
• Superscription (℞)
• Inscription (drug ingredients)
• Subscription
• Signatura
• Refill instructions
• Prescriber’s signature & registration number

🔑 Easy Mnemonic to Remember Parts:

“D-N-S-I-S-S-R-S”
Date
Name
Superscription
Inscription
Subscription
Signatura
Renewal
Signature

LEGALITY OF PRESCRIPTIONS

(Short Notes – Exam Ready)

A legal prescription is one that is written, issued, and dispensed in accordance with statutory laws and professional regulations.

1. Prescribing Authority

• Prescriptions can be written only by legally authorized and registered practitioners.
• In India, prescribing authority is governed mainly by:
• Indian Medical Council Act
• Drugs & Cosmetics Act, 1940
• Drugs & Cosmetics Rules, 1945
• Authorized prescribers include:
• Registered MBBS / MD / MS practitioners
• The scope of prescribing authority varies by country and profession.

⚠️ Medical students are not legally allowed to prescribe medicines.

2. Regulatory Framework

• Prescription, dispensing, and use of medicines are regulated by national laws.
• These regulations define:
• Prescription format and validity
• Record-keeping requirements
• Prescription-only medicines (POM)
• Rules for Schedule H, H1, X drugs
• Non-compliance attracts legal and disciplinary action.

3. Controlled Substances

• Drugs with high abuse and dependence potential (e.g., Schedule X drugs) are strictly regulated.
• Special legal requirements include:
• Mandatory date and signature
• No or limited refills
• Separate registers
• Identity verification
• Dispensing without compliance is a criminal offence.

4. Patient Evaluation

• A prescription must be based on:
• Proper clinical evaluation
• Medical history and diagnosis
• A genuine doctor–patient relationship is essential.
• Prescribing without examination is considered professional misconduct.

5. Documentation and Record-Keeping

• Prescribers must maintain accurate records including:
• Patient details
• Drug name, dose, duration
• Date of issue
• Pharmacists must:
• Preserve prescriptions (especially for controlled drugs)
• Maintain statutory registers
• Essential for:
• Legal compliance
• Continuity of care
• Audit and inspection

6. Adherence to Standards of Practice

Prescribers must follow:

• Ethical principles
• Evidence-based prescribing
• Patient safety and informed consent
• Avoidance of conflicts of interest
• Monitoring for adverse drug reactions

Failure may result in:

• Professional disciplinary action
• Civil or criminal liability

7. Regulatory Oversight

• In India, regulatory control is exercised by:
• Central Drugs Standard Control Organisation (CDSCO)
• State Drug Control Authorities
• (FDA is relevant to the USA, not India — important exam correction)

Regulators oversee:

• Drug approval
• Labeling and advertising
• Post-marketing surveillance
• Enforcement of prescription laws

ELIGIBILITY TO WRITE PRESCRIPTIONS (India-Focused)

Eligible:

• Registered MBBS / MD / MS medical practitioners

Conditionally Eligible (Country-specific):

• Nurses, physician assistants, optometrists, clinical pharmacists
  ➝ Only where specific laws permit

Not Eligible:

• Medical students
• Interns without registration
• Pharmacists (unless legally authorized under special programs)

PRESCRIPTION HANDLING BY PHARMACIST

Verification

Before dispensing, the pharmacist must ensure:

• Prescription is bonafide
• Issued by an authorized prescriber
• Patient identity is genuine

❌ Prescriptions written on:

• Scrap paper
• Cigarette boxes
• Empty strips
  should not be dispensed.

Professional Judgment

The pharmacist must check:

• Rationality of the drug
• Correct dose for age and condition
• Practical quantity prescribed

⚠️ Example:

• A prescription for 20 tablets of Alprazolam requires careful scrutiny and possible clarification.

Clarification with Prescriber

• Any ambiguity, incompatibility, or error → consult the prescriber
• Communication should be polite and professional
• Patient should not be alarmed or made suspicious

🚫 Never dispense a prescription that is:

• Not understood
• Suspected to be incorrect

Dispensing Accuracy (Three-Check Rule)

The label must be checked:

1. When removing the medicine from the shelf
2. When removing tablets from the container
3. Before returning the container to the shelf

This significantly reduces dispensing errors.

Substitution

• Pharmacist must not substitute prescribed medicines without prescriber’s permission (except where generic substitution is legally allowed).

Key Exam Points

• Legal prescription = Authorized prescriber + valid format + legal drug
• FDA → USA | CDSCO → India
• Controlled drugs = strict documentation
• Pharmacist has legal and ethical responsibility to refuse doubtful prescriptions

PRESCRIPTION LABELING

Prescription labeling is a critical step in dispensing, as it guides the patient to use medicines correctly, safely, and effectively. Proper labeling ensures the right drug, right dose, right time, and right duration. Improper or incomplete labeling may lead to medication errors, non-adherence, or harm.

Essential Information on a Prescription Label

A dispensing label should clearly contain:

1.     Patient Details

• Name
• Age
• Sex (where required)

2.     Drug Information

• Name of the medicine (generic ± brand)
• Strength and dosage form
• Total quantity dispensed

3.     Directions for Use (Signatura)

• Dose
• Frequency
• Timing (e.g., after food)
• Duration, if specified
• Route of administration

➝ Must be written in simple, layman’s language understandable to the patient.

4.     Prescriber Details

• Name of prescriber
• Registration number (where applicable)
• Contact details (optional but advisable)

5.     Dispensing Details

• Name of pharmacy
• Name/signature of dispensing pharmacist
• Date of dispensing

Auxiliary / Cautionary Labels

Additional instructions should be affixed where appropriate, such as:

• “Shake well before use”
• “For external use only”
• “Store in a cool place”
• “Keep out of reach of children”
• “Take at the same time every day”

These enhance patient safety and compliance.

Example of a Dispensing Label (Key Elements)

• Patient: Mrs. Geetha Gowda, 45 years
• Drug: Tab. Amodep-AT
• Strength: Atenolol 50 mg + Amlodipine 5 mg
• Quantity: 30 tablets
• Directions: Take one tablet after breakfast. Take at the same time every day.
• Prescribed by: Dr. Karthik Reddy
• Dispensed by: T. Venu, Registered Pharmacist
• Pharmacy name and date

(For exams, focus on components, not brand promotion.)

“DISPENSED” Seal on Prescription

• After dispensing, the pharmacist should stamp or mark “DISPENSED” on the prescription.
• This prevents unauthorized refilling, unless refills are clearly permitted by the prescriber (e.g., Refill ×1).

Patient Counseling After Dispensing

• Patients should be advised on:
• Proper use of medicines
• Storage conditions
• Safe disposal of unused or expired medicines
• Encouraging destruction of unused medicines prevents accidental ingestion and misuse.

FILING OF PRESCRIPTIONS

Legal Importance

• Prescriptions are legal documents.
• In many jurisdictions, pharmacists are legally required to retain dispensed prescriptions for inspection and audit.

Retention of Prescriptions

• Original prescriptions may be:
• Retained by the pharmacy
• Or copied and returned to the patient, depending on local law
• Retention period varies (commonly 2–10 years depending on drug category and jurisdiction).

⚠️ Controlled drugs usually require longer retention and special registers.

Pharmacy Closure or Sale

• If a pharmacy is sold or permanently closed:
• Prescriptions should be transferred to:
• Patients, or
• Another authorized nearby pharmacy, as per regulations

Key Exam Points (High-Yield)

• Prescription label = legal + safety document
• Directions must be clear and patient-friendly
• Auxiliary labels reduce medication errors
• “DISPENSED” seal prevents misuse
• Prescriptions must be properly filed and preserved

IDENTIFICATION OF MEDICATION-RELATED PROBLEMS (MRPs)

Medication-related problems are events or circumstances involving drug therapy that actually or potentially interfere with desired health outcomes.

1. Drug Interactions

Occur when one drug alters the effect or disposition of another.

Types:

a) Pharmacodynamic interactions

• Affect drug action at the receptor or physiological level.
• Example:
• Opioids + benzodiazepines → excessive CNS depression

b) Pharmacokinetic interactions

• Affect ADME (absorption, distribution, metabolism, excretion).
• Example:
• Enzyme induction or inhibition altering plasma drug levels.

Common patterns:

·        Antagonistic interaction
One drug reduces the effect of another.
Example: NSAIDs reducing antihypertensive effect of ACE inhibitors.

·        Synergistic interaction
Combined effect is greater than individual effects.
Example: Opioids + benzodiazepines → increased sedation and respiratory depression.

⚠️ Note: Antibiotics do not routinely reduce oral contraceptive efficacy, except enzyme inducers (e.g., rifampicin) — an important exam correction.

2. Adverse Drug Reactions (ADRs)

• Noxious and unintended responses occurring at normal doses.
• Can be:
• Allergic (e.g., penicillin allergy)
• Predictable (e.g., gastritis with NSAIDs)
• Must be monitored and reported (pharmacovigilance).

3. Medication Errors

Preventable events occurring at any stage of medication use:

• Prescribing errors (wrong drug, dose)
• Dispensing errors
• Administration errors
• Patient non-adherence

Example:

• Incorrect dosing in pediatric or elderly patients.

4. Duplication of Therapy

• Use of two or more drugs with similar pharmacological action without justification.
• Increases risk of:
• Toxicity
• ADRs
• Example:
• Two NSAIDs prescribed simultaneously.

5. Contraindications

• Situations where a drug should not be used due to risk outweighing benefit.

Types:

·        Absolute contraindication
Drug must never be used
(e.g., isotretinoin in pregnancy)

·        Relative contraindication
Use with caution
(e.g., dose adjustment in liver disease)

MANAGING MEDICATION-RELATED PROBLEMS

1. Pharmacist Consultation

• Pharmacists are trained to:
• Detect interactions
• Identify ADRs
• Optimize therapy
• Act as a final safety checkpoint before dispensing.

2. Patient Education

Patients should be counseled on:

• Correct dose and timing
• Possible side effects
• Importance of adherence
• Actions to take if a dose is missed
• When to seek medical help

Proper counseling improves treatment outcomes and safety.

3. Regular Medication Review

• Especially important in:
• Elderly patients
• Polypharmacy cases
• Chronic disease management
• Helps identify:
• Unnecessary drugs
• Interactions
• Therapy duplication

4. Use of Technology

• Drug interaction software
• Electronic Health Records (EHRs)
• Clinical decision support systems

These tools assist in early detection and prevention of MRPs.

KEY EXAM TAKEAWAYS

• MRPs directly affect patient safety
• Drug interactions → pharmacodynamic or pharmacokinetic
• ADRs ≠ medication errors
• Duplication and contraindications are preventable risks
• Pharmacist intervention is clinically and legally significant