Pharmacy Courses

Modified Release Solid Oral Dosage Forms

Modified release oral solid dosage form can be achieved by either incorporating matrix polymers (both hydrophilic or hydrophobic) in the batch formula to be compressed as a tablet or into a hard gelatin capsule shell to deliver the API over up to a period of 24 hours for a longer-lasting therapeutic effect. This is achieved by laying a film of diffusion-controlled membrane.

Modified-release solid dosage drug product can be classified into two major groups:

  1. Extended Release
  2. Delayed Release

Polymers for Modified Release Dosage Form

  • Ethyl cellulose, Methyl Cellulose, Methacrylic acid pH independent polymers; Eudragit® RL and RS or NE/NM systems.
  • Ethocel with a pore former has been widely used in the Pharmaceutical industry for extended-release coating.
  • Many ready mixed aqueous dispersion are also available, e.g. Surelease® from Colorcon.

Pore former for Modified Release Dosage Form

  • Various soluble ingredients; e.g., micronized lactose, mannitol, NaCl or hydrophilic ingredients; e.g, Natural gum, PVP, Na-CMC, HPMC, HPC, pH independent methacrylate, etc.

Delayed Release Dosage Form

The intention for a delayed release drug product is to prevent the release of the API mostly in the stomach; due to various reasons:
  • To protect drug unstable in acidic pH
  • To protect esophagus or stomach from irritation: e.g., doxycycline hyclate, acetylsalicylic acid, iron compounds, etc.
  • Delaying drug release due to food effect
  • GI targeting at different sections of the small intestine or the colon.

Way to Control Delayed Release

  • The pH-dependent polymer is the key element in controlling the dissolution of coated membrane.
  • Drug can be released in a precise manner in specific sections of the GI tract or specific time after intake (specifically for food affect).
  • Among the pH dependent polymers, Polyvinyl Acetate Phthalate and Methacrylate Eudragit® L and Eudragit® S are used.
  • Sodium Alginate, from natural source due to its unique property of congealing in acidic media is also used alone as a clear suspension or with opacifier for enteric coating.

Resource Person: Masihuddin A. Jaigirdar

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