Drug delivery formulations useful to prevent or reduce purposeful or accidental overdose of a drug, and methods of making the same are provided. The formulations comprise either an alkalinizing coat in an amount sufficient to raise the pH of the stomach, or an acidifying coat in an amount sufficient to lower the pH of the duodenum, such that dissolution of an underlying acid or base labile coat is inhibited when excess dosage forms are ingested, thereby reducing or inhibiting the release of the drug contained therein.
