Keeping an Eye on Medical Marijuana for Glaucoma

Jeannette Y. Wick, RPh, MBA, FASCP
Published Online: Thursday, April 11, 2013
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More than a dozen states now allow medical marijuana as a treatment for glaucoma, although medical opinions of its suitability are mixed.

Advocates of medical marijuana often cite its effectiveness in treating glaucoma as a rationale for legalization. Beginning in the 1970s, research showed that marijuana and its active component, THC, decreased intraocular pressure. Increasing public interest in medical marijuana led the American Glaucoma Society to issue a position statement recognizing that marijuana lowers intraocular pressure (IOP), which in turn reduces risk and progression of damage. However, the statement also mentions concerns regarding marijuana’s short duration of action and mood-altering effects. The Glaucoma Research Foundation has also issued a statement on the use of marijuana for treating glaucoma that expresses similar concerns.
According to research trials, 1 dose of marijuana can decrease IOP for 3 to 4 hours. Although the drug’s mechanism of action is not clear at this time, researchers have identified ocular receptors for its active components. Marijuana can be inhaled, taken orally, or administered intravenously. To date, however, researchers have been unable to formulate a topical eye drop—the preferred route of administration for glaucoma treatments—that efficiently delivers the drug.
Beginning this month, medical marijuana will be available to treat glaucoma in Washington, DC. Patients with glaucoma, HIV/AIDS, or multiple sclerosis are allowed to purchase 2 ounces of marijuana every 3 days, according to Washington, DC, regulations. The price has yet to be set but will probably be $100 to $125 per quarter ounce.
Possession, cultivation, and distribution of marijuana are illegal under federal law. In the last 2 decades, however, 15 states have legalized medical marijuana. Although medical marijuana first became legal in Washington, DC, in 2010, the first business to make it available for purchase is only opening now because of potential conflicts with federal law. Recent drug law reform has made growing, prescribing, and using medical marijuana much less difficult, but the federal and state legal systems are still ironing out their differences.
A number of other states have also approved medical marijuana for treatment of glaucoma, including Alaska, Hawaii, Maine, and Nevada. Physicians should check their state’s laws to determine whether medical marijuana is an option for their patients. Other states are also considering or are in the process of making medical marijuana available to treat glaucoma. In Massachusetts, the Department of Public Health just recently released draft regulations. Bills to make marijuana available for medical use have also been introduced in New York and Illinois.
In the medical community, however, the general consensus is that conventional therapies for reducing intraocular pressure outperform cannabinoids.

Ms. Wick is a visiting professor at the University of Connecticut School of Pharmacy and a freelance writer from Virginia.

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