Metformin hydrochloride extended release (ER) formulations have been developed to overcome these problems. Because metformin gets absorbed in the first part of the small intestine, extended release metformin hydrochloride formulations employ various novel gastric-retentive techniques. The polymeric matrix (hydroxyl propyl methyl cellulose) of the extended release metformin tablet is designed to swell in the gastric fluid. As the matrix swells, it becomes resistant to peristalsis and is more easily retained in the stomach. Gastric fluid penetrates the matrix, dissolving the drug which then diffuses out of the matrix in the liquefied form. Metformin hydrochloride is thus slowly released from the matrix of the tablet and is absorbed when this gastric fluid passes through the small intestine. The slow release of the drug in the GI tract permits once daily dosing and also reduces the incidence of nausea (6.5%) and diarrhea (9.6%). These factors are particularly relevant for increasing treatment adherence to long term therapies like anti-diabetic medication.