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A research review published on January 20 in the Journal of the American College of Cardiology suggests that cardiologists should advise patients about the potential risks and effects of marijuana with some commonly prescribed cardiovascular medications, according to SciTech Daily.

More and more states have legalized marijuana for both medicinal and recreational use. As of writing, eleven states ahave already legalized marijuana for recreational use for adults over 21, while 33 states have legalized medical marijuana.

More than 2 million cardiovascular disease patients are currently using marijuana or have used marijuana previously for recreational and approved medical uses, such as human immunodeficiency virus-related weight loss, treatment of seizure disorders, or chemotherapy-associated nausea and vomiting, authors say.

The review further suggests that smoking marijuana carries many affect the heart the way smoking tobacco does.

Dr. Muthiah Vaduganathan of Brigham and Women's Hospital's Heart and Vascular Center in Boston who is the lead author of the review said that some observational studies have suggested an association between marijuana and a range of cardiovascular risks.

"We also know that marijuana is becoming increasingly potent," he said. "Our review suggests that smoking marijuana carries many of the same cardiovascular health hazards as smoking tobacco. While the level of evidence is modest, there's enough data for us to advise caution in using marijuana for our highest-risk patients, including those who present with a heart attack or new arrhythmia, or who have been hospitalized with heart failure."

"The review provides detailed tables of many drugs administered for various cardiovascular conditions, with the anticipated effects of marijuana on each one," Vaduganathan said. "These will be helpful to cardiologists and pharmacists reviewing patients' medications and will help them collaboratively decide whether they need to adjust dosing if the patient continues to use marijuana."

The review also found that certain cardiovascular medications, including statins and blood thinners, can be affected by marijuana use. When statin is used together with marijuana, the statin levels can increase in the blood because both are metabolized through a network of liver enzymes called the cytochrome P450 system. In addition, levels of blood thinners such as warfarin can be expected to increase when used together with marijuana.

The reviewers also recommend that when cardiologists screen their patients for marijuana use, they should determine how often and how much they use. They also should ask about how they use marijuana.

"Vaping marijuana is becoming more and more common, and we know vaping marijuana increases the pharmacological effects of the drug," Vaduganathan said.

The reviewers also advise patients who wish to continue to use marijuana, or who have other medically indicated reasons for use to limit their use as much as possible and for clinicians to inform their patients that certain synthetic forms of cannabinoids are particularly potent and may have greater harmful effects.

The current state of evidence linking marijuana use with cardiovascular health and disease is also reviewed by the researchers.

According to Vaduganathan, there is limited data on the exact health effects of marijuana on the cardiovascular system largely because federal laws classifying marijuana as a Schedule I drug have also limited the ability of scientists to conduct high-quality research.

"Now that we have seen marijuana use become more popular than tobacco smoking, we need more rigorous research, including randomized clinical trials, to explore the effects of marijuana on cardiovascular health," the lead author said.