Safety vs price in the generic drug market: metformin

OBJECTIVES

Generic medications represent 90% of prescriptions in the US market and provide a tremendous financial benefit for patients. Recently, multiple generic drugs have been recalled due to the presence of carcinogens, predominantly N-nitrosodimethylamine (NDMA), including an extensive recall of extended-release (ER) metformin products in 2020.

STUDY DESIGN

Primary pharmaceutical quality testing and database analysis.

METHODS

We tested marketed metformin immediate-release (IR) and ER tablets from a wide sample of generic manufacturers for the presence of carcinogenic impurities NDMA and N,N-dimethylformamide (DMF). We examined the association of level of impurity with drug price and the impact of the 2020 FDA recalls on unit price and prescription fill rate.

RESULTS

Postrecall NDMA levels were significantly lower in metformin ER samples (standardized mean difference = -2.0; P = .01); however, we found continued presence of carcinogens above the FDA threshold in 2 of 30 IR samples (6.67%). Overall, the presence of contaminant levels was not significantly associated with price for either IR (NDMA: R2 = 0.142; P = .981; DMF: R2 = 0.382; P = .436) or ER (NDMA: R2 = 0.124; P = .142; DMF: R2 = 0.199; P = .073) samples. Despite recalls, metformin ER prescription fills increased by 8.9% while unit price decreased by 19.61% (P < .05).

CONCLUSIONS

Recalls of metformin ER medications were effective in lowering NDMA levels below the FDA threshold; however, some samples of generic metformin still contained carcinogens even after FDA-announced recalls. The absence of any correlation with price indicates that potentially safer products are available on the market for the same price as poorer-quality products.

Mechanical amplification of stimuli by hair cells

Unlike any other known sensory receptor, the hair cell uses positive feedback to augment the stimulus to which it responds. In the internal ears of many vertebrates, hair cells amplify the inputs to their mechanosensitive hair bundles. Outer hair cells of the mammalian cochlea display a unique form of somatal motility that may underlie their contribution to amplification. In other receptor organs, hair cells may effect amplification by hair-bundle movements driven by the activity of myosin or of transduction channels. Recent work has demonstrated the presence of several myosin isozymes in hair bundles, confirmed that bundles display myosin ATPase activity, and shown that the work performed by myosin molecules could account for one aspect of the amplificatory process.