What is Prescription – Types | Parts | How to Avoid Errors with Prescription

All Drugs according to Paracelsus are poisons, the difference between a real poison and a drug is just the dose. Therefore, the medical team tries to limit the misuse of these potentially harmful substances known as the Prescription Only Medicines (POM).  Nevertheless, the instruction is that the pharmacist must receive authorization from a Legitimate Prescriber before issuing this type of drug.

Prescription Medicine

What is a Prescription? – How to Avoid Errors


However, this rule does not apply to all drugs. There are drugs that one can walk up to a pharmacist and request without an official document from a prescriber, these drugs are known as Over The Counter (OTC) drugs.

Therefore, A prescription is a medication order issued by a physician, dentist, veterinary doctor, or an authorized prescriber to a Pharmacist to dispense a drug or a medical device to a patient ( animals inclusive). Prescriptions can be written, verbal, typed, or sent as electronic messages.


On this page, We will be discussing the two types of prescriptions, the six Parts and How to Avoid Errors with prescriptions.

Types of prescriptions

Here are the two types you should Know;

a) pre-compounded

b) Extemporaneous or compounding.



Also known as Pharmaceutical compounding, is defined as a prescription instructing the Pharmacist to dispense a drug produced by a pharmaceutical company exactly without alteration of the dosage forms, strength, or dose of the drug. E.g., Cap doxycycline 100 mg b.d × 5/7.

The advantage of pre-compounded prescription over Extemporaneous is the accuracy of dispensing the right dose and also maintenance of proper hygiene.

Extemporaneous or compounding

An extemporaneous prescription is a prescription that requires the pharmacist to prepare by mixing, assembling, packaging, and labeling drugs for a specific patient according to the dose and dosage form prescribed by the physician. E.g.,

Preparation of Ciprofloxacin otic drop
Ciprofloxacin ……………………………………1g
Propylene glycol………………………….50mL
Glycerine………………………….qs ad 100mL

The advantage of Extemporaneous prescriptions over pre-compounded prescriptions is that it is patient-specific ( calculations using age and weight).

Secondly, a patient’s drug is prepared according to body needs. Patients can choose the flavoring agents to improve adherence and excipients that may cause allergic reactions can be replaced.

Parts of valid prescriptions

A typical medication has up of 6 parts namely;

  1. Date
  2. Superscription,
  3. Inscription
  4. Subscription
  5. Signatura
  6. prescriber’s signature.

Here are what you should know about them …

1. Superscription or heading

This is always a pre-printed form carrying the heading Rx which means ( “recipe” or “to take”). Hence, the information of the patient is also seen in the superscription such as name, address, age, and weight. This helps to ensure that each drug gets to the right patient. The age and weight are also used to compound or dispense a drug based on the patient’s need.

This part of the prescription also contains information about the prescriber such as; name, address, and telephone number, this helps the pharmacist to reach out to the prescriber if there is verification or clarification.

2. Date and time of order

Some patients may keep on using the same prescription to purchase the same drug if they are presented with similar symptoms. Notwithstanding, it is important to understand that similar symptoms do not mean the same disease. Therefore, the pharmacist must check if the date of the prescription is current and valid.

Also, Checking the date and a time of a prescription will help the Pharmacist discover when a patient is using the Drugs of abuse wrongly.

3. Inscription or body of prescription

The Inscription part contains information on the drug name ( generic names preferred over brand names), dosage form, and strength of the drug.

The inscription part of the prescription is very important since most Drug Therapy Problems exist in this part of the prescription.  It is, therefore, a core duty of the pharmacist to match the drug given to the Patient’s demographics and condition. If the drug needs of the patient are not met with the prescribed drugs, the pharmacist will call the attention of the prescriber for a review.

4. Subscription

It provides information for the pharmacist or the compounder on what action to take, the quantity of drug to compound or dispense, and its dosage form.

At this stage, improper interpretation of the prescription will cause a great hazard. Therefore, the Pharmacist is to be careful and should ask questions if any instruction from the prescriber is not clear.

5. Signatura

Usually abbreviated as Sig: meaning “mark”, this is a part of the prescription where the prescriber or Physician instructs the pharmacist on the information to be given to the patient on how to use the medication.

This part is the core of patient counseling, the pharmacist has to make sure that the patient understands how to use his/her drug properly. The patient is asked to repeat and demonstrate the procedures as explained.

However, bad communication skills or improper counseling can lead to non-adherence or a predisposing factor to drug misuse.

6. Prescriber’s signature

For a prescription to be valid and authentic, the prescriber has to sign the prescription to confirm its legitimacy.

Qualities of a good prescription.

The pharmacist must ensure that a prescription is correct in its form and content. It has to also be appropriate for the patient intended and is well packaged and labeled. Therefore, a good prescription should have the following qualities;

  • simple and not ambiguous.
  • The handwriting is eligible if written.
  • It contains all the information of a valid prescription.
  • It drugs prescribed should have a therapeutic indication of the patient’s need.

How to avoid prescriptions/medication errors

  • Use a “leading zero” before a decimal point for numbers less than 1. E.g., 0.5 not .5
  • Never use a “trailing zero” after a decimal point. E.g., 5 mg not 5.0 mg.
  • Use a whole number when possible and not an equivalent decimal fraction. E.g., 500 mg not 0.5 g.
  • Always give a space between the number and the unit. E.g., 5 mg not 5mg.
  • Write full names of drugs and not abbreviations. E.g., Penicillin not PCN or Paracetamol not PCM.
  • Do not use “blanket orders” such as, “continue previous prescriptions”.
  • Do not use “range orders” such as 1 to 2 tablets thrice daily.
  • Use USP designations for units of measure. E.g., use g for grams and not Gm nor gms.
  • Spell out instructions clearly and do not use prescription abbreviations. E.g., write daily instead of OD.

Do Read More: Role Of A Pharmacist – Who Is A Pharmacist And What Should They Do


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