Sustained-Release Dosage Forms

• Sustained-Release Dosage Forms


  Dosage forms that control the release of the active ingredient over an extended period of time
• Sustained-Release Dosage Forms


  • Effectiveness, safety and purity of the active ingredients are important
  • Pharmacokinetics must be considered to obtain the desired release profile
  • Controlled release can be achieved in many different ways using polymers
• Controlled release of actives from oral dosage forms with poly(meth)acrylates

  1. Enclosing drugs in diffusion-controlled membranes

  2. Combining neutral, permeable polymers with anionic soluble types to realise various release mechanisms
• As long as undissolved drug is present in the core, its release occurs at a constant rate (zero-order reaction)
• Once the entire drug load is dissolved, release follows a first-order reaction
• Sustained-Release Dosage Forms


  • ZYBAN (bupropion hydrochloride) Sustained-Release Tablets
  • WELLBUTRIN (bupropion hydrochloride) Tablets and WELLBUTRIN SR (bupropion hydrochloride) Sustained-Release Tablets
• ZYBAN


  Non-nicotine aid to smoking cessation, chemically unrelated to nicotine or other agents used in nicotine addiction treatment
• ZYBAN is chemically related to diethylpropion and phenylethylamines
• ZYBAN Tablets are 150-mg, purple, film-coated, sustained-release tablets containing bupropion hydrochloride and various inactive ingredients
• Sustained-Release Parenteral Formulations


  • Used for molecules with short biological half-life that cannot be given orally
  • Improve patient compliance
  • Typical approaches include oily vehicles, aqueous suspensions, and implantable drug delivery systems
• Oily Vehicles


  Formulation approach for poorly soluble molecules, can provide sustained-release profile depending on oil/water partition coefficient
• Aqueous Suspensions


  Can prolong release of compounds with limited aqueous solubility, may contain both immediate-release and sustained-release components
• Aqueous Suspension Formulations


  • Hydrocortisone acetate
  • Medroxyprogesterone acetate
  • Insulin (mixture of amorphous and crystalline zinc insulin)
• Implantable Drug Delivery Systems

  Provide continual drug delivery lasting for months or years, usually supplied with a customised injection device
• Implantable Drug Delivery Systems

  • Norplant® contraceptive device (delivers levonorgestrel for up to 5 years)