TOPICAL ARTHRITIS MEDICATIONS

By Trevor Shewfelt, Pharmacist at the Dauphin Clinic Pharmacy

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The information in this article is intended as a helpful guide only. It is not intended to be used as a substitute for professional advice. If you have any questions about your medications and what is right for you see your doctor, pharmacist or other health care professional.

The other day Linda Watt invited me to talk to Dauphin’s Arthritis Support Group. I’ve talked to them before and they are always a fun and interesting bunch. They usually have lots of feedback and strong opinions, and this time was no exception. They asked me to talk about topical medications for arthritis. Here is some of what we talked about.

Topical medications simply means medications you rub on your skin. To keep them straight in my head, I put them into four groups. I called them Smelly, Skin Deep, Joint Deep and Whole Body.

The smelly topicals smell "mediciny". They usually have menthol, camphor and/or phenol in them. They may heat or cool the skin (e.g. Deep Cold and BenGay). Although some people really like them, they don't have any proven efficacy. The act of rubbing alone might be what makes the joint feel better.

Skin Deep topicals just effect the top layer of the skin. There are over-the-counter (OTC) skin deep topicals that have studies to prove their efficacy. The OTC topical medications that work the best have capsaicin in them. Capsaicin is made from hot chili peppers. Capsaicin does work, but it has its limitations. Capsaicin works on a chemical messenger called Substance P. When Substance P is released from a pain receptor in the skin, a pain signal is started and eventually reaches the brain. When the pain signal reaches the brain, you feel a burning sensation. The interesting thing is there is only so much Substance P, so if you rub capsaicin cream on the area 3-5 times a day, that area runs out of Substance P. With no Substance P, the pain signal can't be started, so no pain! Capsaicin cream has considerable downsides, though. It will make the area hurt MORE the first few applications. If you don't use it regularly 3-5 times per day, the pain will come back. It is made of hot chili peppers, so if you accidentally rub it into your eyes, it will hurt (a lot). Use gloves when applying, or wash your hands really well.

The next group I call Joint Deep. It is actually quite difficult to get a medication through the skin and into the joint. The skin is a very effective barrier to the outside world and one of its jobs is to keep stuff out. One of the first methods I know of that successfully got the arthritis medications called NSAID's through the skin is called Pluronic Lecithin Organogel or PLO. These PLO gels were developed by compounding pharmacists. When you make these PLO gels, the NSAID particles are hidden inside little balls called micelles. If the micelles are made small enough, the micelles can sneak NSAIDs through the skin. It does take some skill and knowledge from the pharmacist to make the PLO gel properly, and all compounded products require a prescription.

So why does it matter if you can get NSAID’s through the skin? Well NSAID's when swallowed in pill form can cause ulcers in the stomach, make a patient bleed more easily and effect their kidney function. So theoretically if we can get NSAID’s directly into the joint we can have all the good effects of reducing pain and inflammation and none of the bad effects. Unfortunately, a small amount of the topical NSAID’s can get passed through the joint to the rest of the body. So even topical NSAIDs have a small risk of causing bleeding problems, ulcers and kidney problems.

The last group of topical medications I talked about, I called whole body topical medications. These include medications like the Fentanyl Patch. This is a powerful narcotic pain killer that can be applied to the skin, but is designed to send medication to the whole body. Some of the advantages of this type of medication is that it is long lasting (one fentanyl patch lasts 3 days) and that it avoids the mouth and stomach. Avoiding the mouth and stomach can be important for example if someone was very nauseous. Although the fentanyl patch can be appropriate for some arthritis patients, its use is reserved for those with the most severe pain.

As always if you have any questions or concerns about these or other products, ask your pharmacist.