Drug strengths, dose, and dosage forms | Medications

Definitions

Drug strength: The amount of drug in a given dosage form. It denotes the amount of active ingredient in each dosage form, e.g., Tylenol 500 mg tablet has a strength of 500 mg, which refers to 500 mg of the active ingredient acetaminophen. Strengths will usually be given as a number with an abbreviation after it, e.g., gram, g/dL, IU, mg. A medication may be available in different strengths, e.g., Tylenol is sold in 325 mg, 500 mg, and 650 mg strengths.
Dose: The amount of drug given at one time. An example of the “dose” for Tylenol for adults and children 12 years and older would be 650 mg of regular strength and 1000 mg of extra strength. The dose can be expressed as milligrams (mg), milliliters (ml), or in other ways like puffs (for inhalers), drops, or numbers like two capsules or three tablets, etc.
Dosage: A broad term that includes how much medication to take at once, how frequently, and how long. An example of the “dosage” for Tylenol, from the label, would be -” For adults and children 12 years and over: For minor aches and pains, take two tablets of Regular Strength Tylenol every four to six hours as needed. Do not take more than ten tablets in 24 hours.”
Dosage form: The physical form in which the drug is manufactured or administered. It depends on how the drug will be administered, e.g., orally, intravenously, via the skin, etc. A drug may be available in multiple dosage forms.

Based on their physical form, drugs can be classified as solids, semisolids, liquids, and gases.

Types of solid drug forms

Tablets: Solid dosage forms containing the active drug with or without excipients. The excipients are substances other than the active drug and include binders, fillers, preservatives, emulsifiers, solvents, etc. Tablets come in different forms. Chewable tablets need to be chewed before swallowing. Oral disintegrating tablets (ODTs) dissolve in the mouth. Sublingual tablets, e.g., sublingual nitroglycerine, dissolve rapidly when kept under the tongue and are useful when rapid action is required, e.g., in heart attacks. Effervescent tablets dissolve quickly in liquids like water, e.g., Alka-Seltzer tablets. Buccal tablets are kept on the inside of the cheek.
Pills: Pills are small, round, or oval medicinal products that are supposed to be swallowed and contain active drugs with excipients.
Capsules: Capsules are a type of solid dosage form consisting of the drug(s) enclosed within a shell of gelatin or other substances. They can be hard or soft gelatin capsules, modified release, or enteric capsules. Modified-release capsules are hard or soft gelatin capsules in which the active ingredient’s release rate is modified. Enteric capsules are hard or soft gelatin capsules that release the active ingredient in the intestine. Sprinkle capsules are a special kind of capsule with small granules enclosed in a capsule shell. The capsule may be swallowed or opened, and the pellets can be mixed with food or beverages and swallowed.
Caplets: Small tablets coated with a film or gelatin, which makes it easier to swallow.
Gelcaps: Made of soft gelatin and contain the active drug in solid or liquid form. They are absorbed more quickly and are easier to swallow. Some pain medications like Tylenol are available in gelcaps.
Powders: Made of finely divided particles in micron sizes.
Granules: Aggregates of powders.
Lozenges: These flat tablets made of edible gum and sugar are used to medicate the mouth and throat.
Pastilles: Hard, jelly-like, and contain glycerin and gelatin.

Types of semi-solid drug forms

Cream: Creams contain more than 20% water or volatile components and typically less than 50% hydrocarbons, waxes, or polyols as vehicles.
Ointment: Ointments are semisolid preparations used topically for protective emollient effects or as a vehicle for local medication administration. Their bases are various mixtures of fats, waxes, animal and plant oils, and solid and liquid hydrocarbons.
Paste: Paste comprises a fatty base and at least 25% of medication.
Gel: Gels are semi-solid dosage forms with a hydrophilic or hydrophobic base mixed with a gelling agent.
Suppository: Suppositories are dosage forms that can be inserted into body orifices like the rectum, vagina, ear, etc. They act locally.
Patch: Also known as transdermal patches, they are adhesive, medicated patches that are applied to the skin and allow the medication to be absorbed through the skin into the bloodstream.
Poultice: A poultice, also called a cataplasm, is a soft, moist mass that is often heated and medicated, spread on a cloth, and then applied over the skin to treat an aching, inflamed, or painful body part.

Types of liquid drug forms

Syrup: Syrup is a thick and sweet liquid used as a carrier for drugs or as a flavoring agent.
Elixir: Elixirs are clear liquid dosage forms containing sugar, water, and alcohol.
Solution: A solution is a clear liquid preparation used for internal or external applications.
Emulsion: An emulsion is a biphasic liquid dosage form where two or more liquids are mixed with the help of an emulsifier, e.g., an oil-in-water emulsion.
Suspension: Suspensions are biphasic liquid forms in which fine solid particles are suspended in a liquid medium.
Lotion: A lotion is a low to medium viscosity liquid dosage form applied over the skin.
Enema: An enema is a liquid dosage form that is inserted rectally.
Liniment: A liniment is a liquid dosage form containing a mixture of oil, alcohol, soap, etc., rubbed into the skin.
Tincture: A tincture is a solution of medication in alcohol, e.g., tincture iodine.

Types of gaseous drug forms

Aerosols: Aerosols are suspensions of fine solid or liquid particles in gas. They are used to apply drugs to the respiratory tract. The mixture is stored in a container under high pressure and released as a fine mist.
Sprays: A spray is a type of aerosol in which the medication is applied as a wet spray, e.g., nasal sprays.
Gasses: Gasses are inhaled for anesthesia, e.g., nitrous oxide, or other purposes, e.g., oxygen.