Objectives Lipid nanoparticles as carrier for oral drug administration improve gastrointestinal solubility of poorly soluble drugs and thus enhance bioavailability. However, basic drugs may undergo rapid dissolution from such solid dispersions in the stomach and precipitate in the intestine due to their higher solubility in acidic medium. Therefore, the objective of this work was to study the enhancement in bioavailability of carvedilol phosphate (basic drug) by providing an alkaline gastric environment to drug-loaded solid lipid nanoparticles. Methods An alkaline gastric environment in rats was created and maintained with oral administration of an antacid suspension 5 min before and 30 min post dosing. Key findings The formulation administered orally exhibited enhanced bioavailability (∼27%) when compared with drug suspension and sustained release behaviour when compared with formulation under ideal gastric conditions. The enhanced bioavailability is due to the presence of lipid nanoparticles as drug carrier while the sustained-release characteristic may be attributed to the presence of antacid, which resulted in elevation of gastric pH and reduced the drug's solubility. Conclusions It may be concluded that although lipid nanoparticles can be instrumental in improving bioavailability, additional sustained release may be achieved by targeting intestinal release of basic drugs from lipid vehicles, which is possible by incorporating them into suitable enteric-coated formulations.