The pharmaceutical industry has synthetically produced the more potent enantiomer Levo-tetrahydropalmatine (Levo-THP), which has been marketed worldwide under different brand names as an alternative to anxiolytic and sedative drugs of the benzodiazepine group and analgesics such as opiates.

In 1940, a Vietnamese scientist Sang Dinh Bui extracted an alkaloid from the root of Stephania rotunda with the yield of 1.2–1.5% and he named this compound rotundin.

[4] Tetrahydropalmatine has been demonstrated to possess analgesic effects and may be beneficial in the treatment of heart disease and liver damage.

[7] In November 2013, the Chinese National Medical Products Administration issued an order asking for all medications containing l-THP to have their package inserts revised, prohibiting use in pregnant women and those with extrapyramidal disorders, requiring warnings about liver impairement and operation of machinery, and highlighting risks of drowsiness and extrapyramidal symptoms with overuse or when combined with other CNS depressants.

[7] Animal experiments have shown that the sedative effect of THP results from blocking dopaminergic neurons in the brain.

All 1999 deaths could be tied to a single THP-based supplement, sold under the name "Jin Bu Huan Anodyne Tablets".

[17] In addition, chronic hepatitis has been reported, caused by THP production in East Asia under conditions that were insufficiently sterile.