Dose, Dosage, Dosage Form, Dosage Regimen

Dose, Dosage, Dosage Form, and Dosage Regimen are often confusing terms. Let’s explain these terms (Dose, Dosage, Dosage Form, and Dosage Regimen).

Dose

The word ‘Dose’ is derived from Middle French Dose, via Late Latin from the Greek Dosis (a portion prescribed or gift) from Didonai (give) [1].

Origin of the word “Dose”

Define-dose

Dose is the predetermined amount of the drug administered at one time to produce a certain degree of biological response in a patient. In addition, the dose of a drug is governed by its inherent potency.

For example, the analgesic dose of Aspirin for headache is 300-600mg, the antiplatelet dose is 60-150mg/day, and the anti-inflammatory dose for rheumatoid arthritis is 3-5g/day. Generally, drug doses are expressed as microgram (µg), milligram (mg), and milliliter. Also, drug doses are expressed as drops (for ophthalmic preparations), various apothecary system measurements (teaspoonful, ounces) and IU (for vitamins, vaccines, hormones, blood products) etc. Various types of doses are therapeutic dose, toxic dose, lethal dose, fatal dose, ceiling dose, loading dose, and maintenance dose.

Dosage

Dosage is the predetermined amount and rate of administration of a drug for a patient. According to the AMA (American Medical Association) Manual of Style, Dosage is the prescribed administration of a predetermined amount, number, and frequency of doses of drug over a specific period of time.

Example of dosage: 200 mg lesinurad once daily.

Dosage Form

Dosage Form refers to the physical form that contains active pharmaceutical ingredients (API) combined with selected additional ingredients (excipients) and intended to be delivered to sites of action within the body by various routes of drug administration. Also, the Dosage form is known as unit doses and drug products. For example,

  1. Solid Dosage Forms: Tablet, Capsule, Pellets, Pill, and Lozenge etc.
  2. Liquid Dosage Forms: Solution, Suspension, Emulsion, Elixir, Linctus, and Gargle, etc.
  3. Semisolid Dosage Forms: Ointment, Cream, and Paste etc.
  4. Gaseous Dosage Forms: Aerosol,and Insufflations etc.

In other words, Dosage Form is the physical form in which a precise mixture of API (active pharmaceutical ingredients) and excipients are presented to help easy administration, deliver to sites of action, achieve rapid onset of action, and improve bioavailability etc.

For example, 250 aspirin tablet. 

Dosage Regimen

The dosage regimen is the frequency at which the drug doses are given to maintain a steady-state serum concentration. Dosage Regimen means the dose of the drug and dosing interval. Simply, the schedule of doses of a therapeutic agent per unit of time [2]. A dosage regimen is meant for the systematized dosage schedule [3].

In other words, the specific way a therapeutic drug is to be taken, including formulation, route of administration, dose, dosing interval, and treatment duration [4].

For example, Amoxicillin 500 mg Tablet, 2 times daily for 14 days.

Usually, the objective of a dosage regimen is to maintain either an average steady-state serum concentration or a minimum or minimum-maximum steady-state serum concentration [5].

Some factors which influence the selection of a dosage regimen include the dosage form of the drug, its pharmacokinetic characteristics, the patient’s pathophysiology, and the patient’s therapeutic needs [6].

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In short:

  • Dose is the predetermined amount of the drug administered at one time to produce a certain degree of biological response in a patient.
  • Dosage is the predetermined amount and rate of administration of a drug for a patient.
  • Dosage Form refers to the physical form that contains active pharmaceutical ingredient (API) combined with selected additional ingredients (excipients) and intended to be delivered to sites of action within the body by various routes of drug administration.
  • Dosage regimen is the frequency at which the drug doses are given to maintain a steady-state serum concentration. Simply, the schedule of doses of a therapeutic agent per unit of time.

References

1. Etymonline.com. (2019). Online Etymology Dictionary. [online] Available at: https://www.etymonline.com/word/dose [Accessed 18 March. 2019]

2. Dosage regimen. (n.d.) Segen’s Medical Dictionary. (2011). Retrieved March 23 2019 from https://medical-dictionary.thefreedictionary.com/dosage+regimen

3. Wagner, J. G. (1969). Biopharmaceutics: 8. Relationship between Dosage Forms, Dosage Regimens and Pharmacokinetics. Drug Intelligence, 3(1), 21–27. https://doi.org/10.1177/106002806900300104

4. National Cancer Institute [Internet]. Bethesda (MD): National Cancer Institute (US). NCI Enterprise Vocabulary Services (EVS); [updated 2015 Jun 12; cited 2017 Oct 12]. Available from: https://ncithesaurus-stage.nci.nih.gov/ncitbrowser/ConceptReport.jsp?dictionary=NCI_Thesaurus&ns=ncit&code=C142516

5. Thompson G. A. (1992). Dosage regimen design: a pharmacokinetic approach. J Clin Pharmacol. 32(3):210-4

6. C. Lindsay DeVane, William J. Jusko (1982). Dosage Regimen Design. Pharmacology & Therapeutics. 17 (2): 143-163. https://doi.org/10.1016/0163-7258(82)90009-2

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