Oral Extended Release Forms can use which mechanisms?

• A. Diffusion, dissolution, osmotic systems
• B. Sublingual absorption
• C. Topical diffusion
• D. Intravenous infusion

Answer: (A)

Oral extended-release dosage forms slow drug release in the GI tract by relying on diffusion, dissolution, or osmotic mechanisms. Diffusion-controlled systems have the drug migrate through a polymer matrix or coat at a controlled rate, so the amount released each moment remains steady. Dissolution-controlled systems release the drug as the solid gradually dissolves from the matrix or barrier, again extending the time over which it enters the body. Osmotic systems use an osmotic pressure gradient to push the drug out through a tiny orifice, delivering it at a relatively constant rate regardless of most GI conditions. These mechanisms together help maintain more constant plasma levels and reduce how often a patient must take the medication.

Sublingual absorption is much faster and bypasses the GI tract, so it’s not used for extended-release in the oral route. Topical diffusion involves the skin, not the oral cavity, and intravenous infusion delivers directly into the bloodstream, not through oral release. Each of those routes or methods does not provide the sustained, controlled release characteristic that diffusion, dissolution, and osmotic systems achieve for oral products.