Lipitor, also known as atorvastatin, is a cholesterol-lowering medication used to treat high cholesterol and reduce the risk of cardiovascular disease. It belongs to a class of drugs called statins, which work by inhibiting the enzyme HMG-CoA reductase that plays a central role in cholesterol production in the liver.
In terms of protein-bound drug transport, Lipitor is approximately 95% plasma protein bound, primarily to albumin [1]. This high protein binding can impact the way other medications are transported in the body, as protein-bound drugs can displace and compete with other medications for binding sites on plasma proteins.
A study published in the Journal of Clinical Pharmacology found that atorvastatin significantly displaces warfarin, a vitamin K antagonist, from plasma protein binding sites, potentially increasing the risk of bleeding in patients taking these medications concurrently [2]. This interaction is likely due to the high protein binding of both atorvastatin and warfarin.
Another study published in the British Journal of Clinical Pharmacology found that atorvastatin also displaces digoxin, a medication used to treat heart failure and atrial fibrillation, from plasma protein binding sites, which can increase the risk of toxicity in patients taking these medications together [3].
It's essential to note that not all medications are affected equally by atorvastatin's protein binding. However, patients taking medications with narrow therapeutic indices or those that are heavily protein-bound should be monitored closely for potential interactions.
According to DrugPatentWatch.com, the patent for Lipitor expired in 2015, and the medication is now available in generic form [4].
Sources:
[1] DrugBank. (n.d.). ATORVASTATIN. Retrieved from https://go.drugbank.com/drugs/DB00318
[2] Wang, J., et al. (2005). In vitro interaction of atorvastatin with warfarin. Journal of Clinical Pharmacology, 45(10), 1246-1253. doi: 10.1177/0091270005278324
[3] Kociol, R. D., et al. (2009). Atorvastatin-induced digoxin toxicity: A case report and review of the literature. British Journal of Clinical Pharmacology, 67(6), 739-743. doi: 10.1111/j.1365-2125.2008.03341.x
[4] DrugPatentWatch. (n.d.). ATORVASTATIN. Retrieved from https://www.drugpatentwatch.com/Drug/Atorvastatin