Lawsuit
In the 2000s a lawsuit was brought against the manufacturers of Toprol XL (a time-release formula version of metoprolol) and its generic equivalent (metoprolol-succinate) claiming that to increase profits, lower cost generic versions of Toprol XL were intentionally kept off the market. It alleged such action by the pharmaceutical companies AstraZeneca AB, AstraZeneca LP, AstraZeneca Pharmaceuticals LP, and Aktiebolaget Hassle violated antitrust and consumer protection law. A settlement was reached in 2012, with the above manufacturers paying out $11 million in damages. Environmental presence
In 2021, metoprolol was one of the 12 compounds identified in sludge samples taken from 12 wastewater treatment plants in California that were associated with estrogenic activity in in vitro. References
Further reading
Dean L (2017). "Metoprolol Therapy and CYP2D6 Genotype". In Pratt VM, McLeod HL, Rubinstein WS,  et al. (eds.). Medical Genetics Summaries. National Center for Biotechnology Information (NCBI). PMID 28520381. Bookshelf ID: NBK425389. External links
"Metoprolol". Drug Information Portal. U.S. National Library of Medicine.
Diagnosis
Blood tests
Routine blood tests show features of acute inflammation (raised white blood cell count and elevated C-reactive protein level), and usually abnormal liver function tests (LFTs). In most cases the LFTs will be consistent with obstruction: raised bilirubin, alkaline phosphatase and γ-glutamyl transpeptidase. In the early stages, however, pressure on the liver cells may be the main feature and the tests will resemble those in hepatitis, with elevations in alanine transaminase and aspartate transaminase.Blood cultures are often performed in people with fever and evidence of acute infection. These yield the bacteria causing the infection in 36% of cases, usually after 24–48 hours of incubation. Bile, too, may be sent for culture during ERCP (see below). The most common bacteria linked to ascending cholangitis are gram-negative bacilli: Escherichia coli (25–50%), Klebsiella (15–20%) and Enterobacter (5–10%). Of the gram-positive cocci, Enterococcus causes 10–20%. Medical imaging
Given that ascending cholangitis usually occurs in the setting of bile duct obstruction, various forms of medical imaging may be employed to identify the site and nature of this obstruction. The first investigation is usually ultrasound, as this is the most easily available. Ultrasound may show dilation of the bile duct and identifies 38% of bile duct stones; it is relatively poor at identifying stones farther down the bile duct. Ultrasound can help distinguish between cholangitis and cholecystitis (inflammation of the gallbladder), which has similar symptoms to cholangitis but appears differently on ultrasound. A better test is magnetic resonance cholangiopancreatography (MRCP), which uses magnetic resonance imaging (MRI); this has a comparable sensitivity to ERCP.