Dosage Forms I

• Dosage form


  The physical form in which a drug is produced for administration to the recipient. It can be solid, liquid or semi-solid.
• Drug delivery system


  A modern term used in place of ''conventional dosage forms'' to describe a system for carrying a drug into the body. Refers to both the construct of the drug, its delivery vehicle, and its method of administration.
• The physical form of the oral dosage form


  Influences absorption rate and onset of action
• Oral solutions


  Absorbed faster than tablets and so act quicker
• Oral solutions


  Already in soluble form and so is ready to be absorbed
• Tablets


  Must be disintegrated first in the body, dissolved in the gastric content and then absorbed
• Administration Route


  • Oral
  • Inhaled (pulmonary)
  • Ear
  • Eye
  • Nasal
  • Rectal
  • Topical
  • Parenteral
  • Vaginal
• Oral Dosage Forms


  • Tablets
  • Capsules
  • Granules
  • Powders
  • Pastilles
  • Solutions
  • Suspensions
  • Emulsions
  • Lozenges
  • Pastes
  • Chewing gum
• Same drug maybe presented in several different dosage forms and strengths to meet specific needs of user
• Most acceptable formulation should be given to patient with consideration of the clinical indication being treated and patient factors
• Excipients


  Inactive components added to improve the final physical form of the dosage form, e.g. bulking agent, disintegrant (helps tablet to break down) etc.
• Tablets


  Solid preparations prepared by compression
• Tablets


  • Oral delivery is the most popular route of drug administration and among oral dosage forms, tablets is the most common form
  • Originated from the Latin (tabuletta) which means disc-like or cylindrical
  • The tableting machine is made up of an upper and lower punch. The pharmaceutical powder containing the drug and excipients is placed in between them and it's compressed to form the tablet.
• Tablet manufacturing by moulding


  The powder, which is wet, is placed in a mould and left to dry
• Tablet manufacturing by freeze drying (lyophilisation)


  A solution of the drug is prepared together with the excipients and it's placed in a mould. It's placed in a special chamber known as a freeze drying chamber where the pressure and temp is reduced. The solution is frozen first and the water content becomes ice. Then, at a low pressure, and all the water content in the solution is sublimed, changing from solid ice crystals into water vapour and removing the water. This leaves a dry powder that takes the mould shape and this is the tablet.
• Tablet Excipients


  • Filler (bulking agent)
  • Disintergrant
  • Solution binder
  • Dry binder
  • Glidant
  • Lubricant
  • Antiadherent
• Single-punch press (eccentric press)


  One pair of punches and one die. Die is filled with powder by gravity when hopper shoe is over the ide. Upper punch moves down and compress the powder. Production of small batches, 200 tablets/minute.
• Rotary press

  360 dies and set of punches. 10 000 tablets/minute.
• Types of Tablets


  • Immediate Release
  • Delayed Release (m/r or s/r)
  • Effervescent
  • Soluble/Dispersible
  • Chewable
  • Buccal or Sublingual
  • Sugar coated or film coated
  • Enteric coated
• Effervescent tablets


  When making the tablet, weak acids such as citric acid and a base such as bicarbonate are compressed together. When water is added, the chemical reaction between the weak acid and bicarbonate is initiated and carbon dioxide is released in the form of bubbles. Tablet then breaks up and active ingredient is released and dissolves in the water.
• Buccal or Sublingual tablets


  Small and flat. Not to be swallowed whole. Placed under the tongue, which has high vascularity, so there's a high blood supply in this area, meaning the drug can be absorbed very fast and a fast therapeutic effect can be achieved.
• Enteric coated tablets


  Protects drug from the acid conditions of the stomach, preventing tablet from dissolving until reaches the small intestine.
• Lozenges


  Drug incorporated in flavoured base. Dissolve or disintegrate slowly in mouth, releasing medication generally for localised effect e.g. antiseptics for sore throat. Also get lozenges that produce systemic effect e.g. nicotine lozenges.
• Pastilles


  Glycerol and gelatin base. Sweetened ,flavoured and medicated. Sucked, very popular for soothing coughs/sore throats
• Soft gelatin capsules


  One piece capsules containing a liquid or semi-solid fill e.g. cod liver oil
• Hard gelatin capsules

  Two piece capsules shells filled with powders, pellets, semi-solids or liquids. The bottom part is the body and top part is the cap. When the capsule is filled, the cap is taken off, the pharmaceutical powder is placed in the body and then the cap is replaced. The capsule is then slightly compressed.
• Oral Powders and Granules

  • Bulk powders (undivided powders)
  • Individually wrapped doses (divided powders)
  • Granules/powders for reconstitution before dispensing
  • Effervescent granules
• Advantages of Powders/Granules


  • Solid preparations are more stable than liquid preparations
  • Convenient forms in which to dispense drugs with a large dose
  • Useful for patients who have difficulty swallowing tabs/caps or where rapid absorption of the drug is required
• Disadvantages of Powders/Granules


  • Bulk powders or granules are less convenient to carry than a small container of tabs/caps
  • Masking of unpleasant taste maybe a problem
  • Bulk powders or granules are not good method of administering potent drugs with low dose
  • Not a suitable method of administration of drugs that are inactivated in the stomach
• Oral solutions


  Contain one or more ingredients dissolved in a suitable vehicle, usually solids dissolved in liquids
• Different Types of Pharmaceutical Solution Used Orally


  • Syrups
  • Elixirs
  • Linctuses
  • Mixtures
• Advantages of Oral Solutions

  • Absorption of the medicine from the GI tract is rapid, as they're already in the soluble form
  • Easy to swallow for children and some adults esp. the elderly, who may have swallowing difficulties
  • Uniform distribution of medicament, no need to shake
  • Flexible dosing is possible
• Disadvantages of Oral Solutions

  • Medicaments are less stable in solution than in a dry dosage form
  • Unpleasant flavours maybe difficult to mask
  • Bulky to carry around
  • Vulnerable to loss by breakage of container
  • A means of measuring the dose is required
  • Measurement depends on the accuracy and reliability of the patient
• Suspensions


  A disperse system in which one substance (the disperse phase) is distributed in particulate form throughout another (the continuous phase). In a suspension at least one of the ingredients is not dissolved in a vehicle.
• Advantages of Suspensions


  • Insoluble drugs maybe more palatable — wouldn't taste bitter as drug isn't dissolved in vehicle
  • Absorption will be quicker than solid dosage forms
• Disadvantages of Suspensions


  • Preparation requires shaking before use
  • Accuracy of dose likely to be less than equivalent solution
  • Isn't very stable — if they're left for too long, they can precipitate at the bottom of the bottle and form a cake, affecting the accuracy of the dosing
• Emulsions


  Liquid preparation containing a mixture of oil and water; they can be oil in water or water in oil. Emulsifying agent ensures that the oil phase is finely dispersed throughout the water as minute globules.
• Generally all oral dose emulsions tend to be oil in water
• Ear Drops


  Drug/mixture of drugs is presented as a solution or suspension. Vehicle may be water, although glycerol and propylene glycol may also be used. Designed to exert local effect in the ear, e.g. to soften wax Almond Oil or Olive Oil), to treat local inflammation and infection or to relieve pain.
• Eye Drops


  Sterile solutions or suspensions of one or more medicaments. Drops can be supplied in single or multiple dose containers.