Pharmaceutical Dosage Forms Overview

Pharmaceutical Dosage Form

• Defined as a combination of drug (active pharmaceutical ingredient (API)) and excipients in a certain configuration.
• Drug: the active pharmaceutical material that alters the biological condition.
• Excipients: inactive materials with various functions during manufacturing, storage, and use of formulations.
• Advantages of dosage forms:
  • Deliver the correct amount of drug conveniently and acceptably to the patient.
  • Control drug delivery, including fast-onset and extended-release options.

Classification of Dosage Forms

• Based on Route of Delivery:
  • Pulmonary
  • Parenteral
  • Transdermal
  • Nasal
  • Ophthalmic
  • Otic
  • Vaginal
  • Rectal
  • Oral Dosage Form
• Based on Physical Form:
  • Solid
  • Semisolids
  • Liquid
  • Gaseous

Stages in Manufacturing a Dosage Form

• A- Pre-formulation stage: preliminary studies to identify physical and chemical properties of the medicinal substance to indicate its efficacy and bioavailability.

  • Evaluation of particle size, solubility, stability, excipient compatibility, and crystal/surface properties.

• B- Biopharmaceutical studies: discover the rate and extent at which the candidate drug is available at the site of action, including:

  • Pharmacodynamic studies: the effect of the drug on the body (therapeutic effect, toxic effect, and adverse drug reaction).
  • Pharmacokinetic studies: the effect of the body on the drug (absorption, distribution, metabolism, and excretion).
  • Product analysis: several candidate dosage forms are evaluated, measuring bioavailability and pharmacokinetics, determining preferred dosage form and required dose.
  • Other studies: patient compliance, manufacturing cost, and stability of the final dosage form.

• C- Formulation and development: involves the actual formulation of the desired dosage form.

Tablet Dosage Form

• The oral route is the most important method of administering drugs for systemic effects, with 90% of drugs administered orally.
• Tablets are the most common form of orally administered dosage forms.
• Tablets consist of API and excipients, varying in size, shape, weight, hardness, thickness, disintegration, and dissolution characteristics (depending on intended use/manufacturing method).
• Tablets are usually prepared by compression.

Advantages of Tablet

• Unit Dosage Form (accurate dose).
• Lightest and most compact oral dosage form.
• Easy to handle, store, and dispense tamperproof.
• Easier to ship and package than capsules.
• Lower manufacturing cost than most other dosage forms.
• Simple and cheap identification, often achieved with embossed or monogrammed punch faces.
• Ease of swallowing, especially when coated (requires less rapid disintegration).
• Well-suited for large-scale production.
• Combines good chemical, mechanical, and microbiologic stability.
• Easy-to-control and manipulate release profile.

Disadvantages of Tablet

• Some drugs resist compression into a dense compact due to their amorphous or flocculent nature/low-density character.
• Not ideal for hiding bad taste or smell of some APIs. APIs susceptible to oxygen or atmospheric moisture may require encapsulation or entrapment.
• Difficulty formulating drugs with poor wetting properties/slow dissolution. Some drugs degrade when administered orally.

Types of Tablets

• Compressed tablet (plain tablet): uncoated

  • Intended for rapid disintegration, providing rapid drug release.
  • Often used for local GI effects (e.g., antacids, adsorbents).
  • Also used for systemic circulation, especially for acidic drugs that dissolve well in the upper GI tract (e.g., ibuprofen).

• Multiple compressed tablets

  • Layered tablets and compression-coated tablets (tablets within a tablet).
  • Contain two or more components separated, formulated through multiple light compressions followed by a final compression for the entire tablet.
  • Prepared to separate physically/chemically incompatible ingredients or to produce multiple/prolonged-action products.
  • Drawbacks: slower production speed, difficulty controlling release of each layer (especially if layers are designed to disintegrate at different points in the GI tract). Blood levels related to gastric emptying time are variable. This limits their production and use.

• Chewable tablets

  • Intended to be chewed in the mouth before swallowing, not swallowed whole.
  • Primarily used for children and those with swallowing difficulties.
  • Useful for potent/bitter drugs that are large in dose (e.g., aspirin, antacid tablets). Chewablility enhances particle size action/complimance.

• Sugar-coated tablets

  • Coated with a sugar layer.
  • Used to improve the elegance of the tablet.
  • Useful for masking unpleasant tastes/odors of the medication. Sugar coating is water-soluble and quickly dissolves after swallowing. (e.g., flu-out® tablet).

• Film-coated tablets

  • Alternative to enteric or sugar coating.
  • Often developed for elegance and improved control of the drug release profile.

• Repeated action tablets

  • One type of extended-release dosage form.
  • Specific type of multiple compressed tablets designed for each layer to release its component at a specific time, allowing for prolonged drug action. (e.g., anti-allergy medications).

• Delayed action and enteric-coated tablets

  • Covered with a shell that doesn't dissolve in gastric acid.
  • Dissolves in the small or large intestine, releasing the drug at a later stage (delayed absorption).
  • Used to protect the stomach from irritation caused by some medications, especially those that are destroyed by gastric acid (e.g., aspirin).

• Buccal and sublingual tablets

  • Designed to dissolve/release active component quickly and in small volume in oral mucosa.
  • Drugs pass directly to systemic circulation, avoiding first-pass metabolism.
  • Results in a faster onset of drug action. (e.g., nitroglycerin tablet)

• Troches and lozenges

  • Used in oral cavity; intended to exert their effect in the mouth or throat.
  • Prepared by compression for slow dissolution in the mouth.
  • Not intended for disintegration. (e.g., cough drops).

• Dental cones

  • Type of tablet used after tooth extraction.
  • Contains antibacterial chemicals for slow release, reducing bleeding.

• Implantation tablets

  • For subcutaneous implantation to release medicine over a prolonged time.
  • Often small and cylindric/rosette shaped tablets, normally less than 8mm in length.
  • Administered with a special syringe or via surgical procedures.

• Vaginal tablets

  • Designed for slow dissolution and drug release in the vaginal cavity.
  • Usually oval shape, often with applicators.

• Effervescent tablets

  • Designed to make a solution rapidly with release of carbon dioxide.
  • Contain citric acid plus sodium bicarbonate; high patient acceptance. Provide accurate dose comparable to liquid forms, adaptable for stomach PH adjustments.

• Dispensing tablets

  • Used by pharmacists to prepare more concentrated drug solutions.
  • Typically large/high doses for solution making.

• Hypodermic tablets

  • Contain water-soluble drugs intended to prepare solutions for injections when added to sterile water.
  • Due to advances in manufacturing, hypodermic tablets are not commonly used today.

Ideal Tablet

• Elegant appearance, free from defects (chips, cracks, discoloration, etc.).
• Resistant to mechanical shock during production, packaging, shipping, and dispensing.
• Maintains chemical and physical stability during shelf life.
• Predictable and reproducible release of medicinal agent(s) in the body.
• Preserves chemical stability of the drug during extended time.

Tablet Ingredients

• Must be nontoxic and legal in target markets.
• Must commercially available for manufacturing.
• Reasonable cost effective.
• Not contraindicated in any segment of the population or due to associated ingredients.
• Physiologically inert.
• Chemically and physically stable, individually and in combination with other tablet components.
• Free or unacceptable microbial contaminations.
• Color compatible (does not alter the original color intensity).
• Must not alter bioavailability (e.g., for excipients).

Tablets Excipients

• Detailed descriptions of various excipients (antioxidants, anti-adherents, binders, diluents, disintegrants, glidants, lubricants, etc.) and their purposes. Specific examples are included.

This quiz covers the essential aspects of pharmaceutical dosage forms, including definitions, classifications based on route and physical form, and the stages involved in manufacturing. Test your knowledge on the active pharmaceutical ingredients and excipients that comprise these formulations.