Until recently, pharmacologists did not fully understand APAP’s mechanism. That is, exactly how does it relieve pain and reduce fevers? Considering the only other non-opioid analgesics consist entirely of the non-steriodal anti-inflammatory drugs (NSAIDs) such as ibuprofen and naproxen, APAP’s mechanism was assumed to be a similar one. NSAIDs work by inhibiting enzymes called cyclooxygenase (COX) which produce chemical messengers called prostiglandins which set off inflammation and pain. While NSAIDs markedly reduce inflammation, there is almost little to no inflammation reduction with APAP usage. Why is this?

There are two varieties of cyclooxygenase: COX-1 and COX-2. Most NSAIDs inhibit both of these types equally. COX-1 inhibition has the unwanted side-effect of reducing protective liners in the stomach which can lead to gastric bleeding (indeed, the number one problem with NSAID use). However, inhibition of COX-2 does not produce this effect. Due to this, a number of drugs were developed that selectively inhibit COX-2 while leaving COX-1 alone, and these drugs were called “COX-2 inhibitors” with drug name suffixes of “coxib,” for “COX inhibitor.” Examples of such drugs include valdecoxib, rofecoxib, and celecoxib. A number of these drugs were developed and were very well-regarded by pain management physicians and chronic pain patients alike for their excellent ability to lower pain and inflammation without marked side-effects and even alleviated the need for opioid use (or at least reduced it). Unfortunately some of these drugs were abruptly removed from the United States market and, aside from celecoxib, no new COX-2 inhibitors have been approved or remain on the US market.

So where am I going with this? As APAP’s mechanism becomes more clear, recent findings have suggested that APAP is strongly selective of COX-2 (so much for the need to remove them from the market). So while APAP does indeed inhibit COX like the NSAIDs, there is strong evidence that APAP works through at least two pathways. The first one is well-researched and well-understood (COX inhibition), and the second pathway is what we’re interested in. So what exactly is going on here?

Recent research suggests that APAP may earn its analgesic and antipyretic properties by indirectly activating the endogenous cannabinoid system. The same way that opioids activate our own natural pain-relief system that endorphins and other natural ligands use, the body also has a natural cannaboinoid system which is responsible for the effects of tetrahydrocannabinol, or THC, which is the main active ingredient found in marijuana. Just like morphine binds to opioid receptors (mu, kappa, delta, and others), drugs like marijuana bind to the cannabinoid receptors CB1 and CB2. A well-known natural opioid is endorphin. There are also natural cannabinoids, and the one floating around our brains is called anandamide. The entire purpose of the endogenous cannabinoid system has yet to be fully elucidated, but we will explore some of the regulatory functions they serve below.

When you take APAP, it is metabolized by the body into a number of different chemicals. Some are active, some are inactive. One particular metabolite is taken in by an enzyme in the body called fatty acid amide hydrolase (or FAAH), which converts it into a metabolite called AM404. AM404 is versatile. It’s effect is as an analgesic and an antipyretic (sound familiar?). AM404 inhibits FAAH, which also metabolizes anandamide (the natural cannabinoid). The net effect is that anandamide uptake is inhibited, and levels of anandamide in the brain increase. AM404 also directly inhibits the formation of COX-1, COX-2, and prostaglandins (sound even more familiar?). AM404 also activates a receptor called TRPV1, which is also where the substance capsaicin (the substance that makes hot peppers hot) binds. TRPV1 is responsible for pain transmission and thermoregulatory actions. When activated, TRPV1 enhances and modulates pain transmission, and also tells the body to cool itself down. However, when TRPV1 is bound to for long periods of time it “shuts down,” preventing it from functioning, thus reducing pain.

So let’s take a step back. We’ve got a lot of things going on. Thanks to AM404–which is introduced by acetaminophen–we have the following things going on:

1. AM404 inhibits FAAH–which metabolizes anandamide–resulting in an increase of anadamide.
2. Anadamide binds to cannabinoid CB1 and CB2, and also activates the TRPV1 receptor. Each of these actions are known to inhibit pain on their own.
3. AM404 also activates the TRPV1 receptor.
4. AM404 also inhibits cyclooxygenase and prostagladins.

All of these processes are working to reduce pain (and fever). So, what does this really matter? By investigating these processes we can create novel analgesic drugs that aim to inhibit FAAH in the same way AM404 does (APAP’s use itself is limited due to its toxicity at higher doses) and giving rise to this exact process. We can also make drugs to target TRPV1, and in fact there are already several in advanced testing phases (both agonists and antagonists are being explored, but I’d personally be interested in a partial agonist–can we activate and overload it without causing the burning sensations?).

Let’s remember, this started by looking closely at the metabolism and mechanism of a drug almost everyone worldwide knows of and has made use of: acetaminophen. First we found out that APAP is most likely a highly selective COX-2 inhibitor, and so that trash about taking Bextra and Vioxx off the market was just that: trash. More importantly–if you’ve managed to follow along–you’ve almost certainly deduced that because acetaminophen introduces AM404, and AM404 causes activations in the endocannabinoid system, and in this fashion acetaminophen acts as a pro-drug for a cannabimimetic metabolite (AM404 itself), this means that Tylenol and Panadol and hugely popular drugs containing acetaminophen are activating the endocannabinoid system–like marijuana–in order to produce it’s primary effect of analgesia. Tylenol’s pain-relieving action involves activation of the endogenous cannabinoid system.

And marijuana is illegal?

In May I met–for the last time–with my pain management physician. He refilled all my medications and told me which physician I’d be seeing until he gets set up somewhere. This was now not a certainty as I’d been led to believe before. Now he may or may not continue his practice elsewhere, and I’m somewhat concerned. I take the scripts and bid him farewell.

Thirty days later it’s time for a refill. I don’t have a treating physician anymore. I call the office and they arrange for a one-time 30 day refill of my medications in exchange for a urine sample. Apparently it was horrible of my previous physician to simply trust me and not require urine analyses (UAs) in the past, and some more stuff about why he’s a bad doctor and I should stay there. I’m told to make an appointment with the new physician. The appointment was 52 days away, and I had scripts for 30 days.

Thirty days later it’s time for a refill. I call up and this time I’m told that I’m not allowed a refill. Why not? Apparently it was “made clear to me” that the previous script was a “one-time thing” (which it wasn’t [made clear to me]). I was supposed to get an appointment before those scripts ran out! Wait, I did make an appointment. It was 52 days away. How am I supposed to get one 30 day script when my appointment was more than 30 days away? Well, according to “the system” my appointment was “just created” (likely because someone modified it or something and it changed the date it was edited) and that means I didn’t make an appointment and it’s my fault. I go in and they decide that, for yet another urine sample, I may obtain 14 days worth of my medication. Except that you can’t fill 14 days of fentanyl patches because they come in boxes of 5 and 14 days would be 7 patches and they can only fill them per box, so they only give me 5. I tell the office this. When my urine comes back “clean” they give me another 30 days.

Not quite thirty days later is finally time for my appointment. I come in for my new physician, the one that’s been writing these scripts, and the first words out of his mouth consist of some FUD about my current treatment being all wrong, and it’s very wrong for someone as young as me to be on “two hardcore narcotics” (he specifically and repeatedly used the word “narcotic” over “opiate” or “opioid”–both of which are more appropriate for medical professionals–because “narcotic” is a scary-sounding word) and instead I should look into permanent back surgery. I argue that I have no surgical options given my condition and that I’ve already had every interventional procedure that I could have. He tells me of an orthopedic surgeon I should immediately go see for a second opinion. As it turns out I know this orthopedic surgeon. He referred me to pain management–to the very office I am currently sitting in. When I tell him this I’m still instructed to “go back” to get new radiographs and with new radiographs, a new opinion on surgery. The surgeon had before told me the only thing he could offer me were spinal fusions. I turned him down given my age, which he agreed with, and he sent me to pain management which he deemed, in his own words, “the only reasonable next step.” Two years later my only reasonable next step is backwards, it seems. The new physician continues to try to alarm me about my current treatment, telling me that my medications are “dangerous and addictive.” I tell him I’ve been on them off and on for four or five years and have yet to have any issues with abuse or addiction, and that every UA he’s ordered on me has come back pristine. He tells me that narcotics build up in the body and always eventually cause addiction and that they’ll make me sleepy and surely I must be intolerably constipated and throws in every other classic opioid side effect, trying to get me to admit that there’s a reason to discontinue the therapy. I tell him no, the only side effect I even notice is constipation and I simply have a fiber bar or two every day and don’t even notice the difference. He’s angry, realizing that I’m actually educated about my condition and the treatment and ties up the appointment by telling me I have until August to find “other options” before he discontinues my medications.

One of the best parts of this whole thing is that when I first got there a resident finishing up her fellowship came in and talked to me first. After she went through everything she agreed with my current treatment and, after asking how it was working, thought I should increase my fentanyl dose (which I’ve been wanting to do for months). When the attending came in and shot down all that with his bullshit, she looked rather put off and disappointed. I don’t know if she was disappointed because he didn’t agree with her and thus she must be wrong, or because he was being so obviously obtuse about my treatment and there was nothing she could do to help me. The best part of this was that his own Fellow disagreed with him and thought my current treatment should stand. I liked her. She was a very nice lady. I’m sad I’ll never see her again.

Currently I’m waiting for some results from various tests I had with my rheumatologist. He’s a very smart physician. While he doesn’t know exactly what’s wrong with me (he suspects an extremely mild non-specific “type” of Ehlers-Danlos Syndrome, but it’s a wild shot) he told me he was positive it wasn’t progressive osteoarthritis, which is what my pain clinic has been telling me for two years. They also tell me it “just happens,” even to males in their early 20s. I’m also expected to see the orthopedic surgeon that originally referred me to the pain clinic in the first place. I’m not totally sure I’m going to do this, because I don’t see the point. I’m not going to have surgery, and the last time I saw him my options were “surgery or pain management.” Guess which one I chose.

Monday I’m going to talk to my primary care physician about what she could do for me if I lose my medications. The Monday after that I’m going to get the results of all my rheumatology tests, and maybe have an answer and even treatment. If all of this fails, come August I’ll have no answers and no pain management. I will have to quit my job, move home to St. Louis, and try desperately not to curl up into a miserable ball of existence, wondering why I should continue to bother to live.

According to various medical texts, the brain is not designed to be in pain for a long period of time. In fact, the nervous system in general is not designed to send “pain signals” for very long at all. As such, when chronic pain happens often times the neurons that send these signals “learn” to get better at sending them, in the way that your brain learns for memories. A common myth is that people exposed to pain frequently have a higher “pain tolerance,” when in fact the opposite is true. The more often you’re exposed to pain, the more adept your nervous system becomes at sending pain signals. If the same neurons send the same signals for long enough, something called neuronal plasticity happens: in laymen’s terms, those neurons physically change themselves to permanently transmit pain. There is no definitive way to tell when something like this has happened to someone, but it’s a good bet that when all interventional procedures such as disconnecting the nerves themselves (rhizotomy) still fail to provide pain relief, you have this situation. This is bad. There is no way to reverse this process. Your body is now in constant pain. In medical terminology:

Under persistent activation nociceptive transmission to the dorsal horn may induce a wind up phenomenon. This induces pathological changes that lower the threshold for pain signals to be transmitted. In addition it may generate nonnociceptive nerve fibers to respond to pain signals. Nonnociceptive nerve fibers may also be able to generate and transmit pain signals. In chronic pain this process is difficult to reverse or eradicate once established.

Being in constant pain is not only–you know, painful–but it also wreaks havoc on your body. People with high-intensity chronic pain have significantly reduced ability to perform attention-demanding tasks. Pain appears to strongly capture the attention of people with chronic pain; tests assessing the ability to attend show poorer performance than pain-free people on all tests demanding attention. The exception is found with tasks that are highly demanding of attention, where performance between the two groups is equivalent. In experimental testing, two-thirds of individuals with chronic pain demonstrate clinically significant impairment of attention independent of age, education, medication and sleep disruption. Individuals with the highest levels of pain showed greatest disruption of memory traces, suggesting that pain diminishes working memory.

Now that I’ve gotten some of that out of the way, I have another story about physical medication side effects. Last week I was at work. I work some two hours from my home. Right before leaving, I went to use the bathroom but found it difficult to urinate. I didn’t really give this much thought because I’ve had a “shy bladder” for close to a decade. It’s always been stressful and difficult for me to give urine samples for job applications or other reasons. I left work and when I got home a few hours later, I was still unable to urinate. This worried me. Since I usually get home late I tried a few more times and went to bed. When I got up in the morning and got to work I found myself still unable to urinate. At this point I was still leaning toward a shy bladder and figured that if I drank enough I could sort of force it out. This is the technique I use to give urine samples. A few hours later I was very much surprised to find that this didn’t work.

After consuming a large amount of fluids I felt as if my bladder were going to burst and I was in quite a large amount of pain and discomfort. I immediately ran to the bathroom where I was still totally unable to urinate. I realized at this point I had an emergency condition on my hands and tried to convince my carpool to start heading home immediately. By the time they had gathered their things I realized there was no way I was going to make it two hours back home, and decided to run to the hospital across the street from work.

Upon walking into the ER I told the triage nurse I hadn’t urinated for 22 hours and I was in severe discomfort. After a quick sign in with a list of medications and allergies I was rushed off to a room where she quickly (and not as horrifyingly painfully as last time) inserted a Foley catheter where she promptly drained close to 950mL of urine (a normal liquor bottle is 750mL). I felt much better. After a discussion with the physician about the possible causes he was leaning toward my pain medication, as opioids are a frequent cause (but individually rare (less than 10%) side effect) of urinary retention. After a urine analysis (I didn’t have trouble giving a sample this time–it came out of a tube), blood work, and a couple of non-contrast abdominal and pelvic CT scans all came back normal I was told the most likely culprit was the “vast amount of narcotic medications” and advised it would be best the catheter stayed in a few days. I was not entirely happy with that verdict. As I limped out of the ER (and when you’re a male with a tube up your penis, you limp) I was picked up by my carpool and taken home. After a few days of being told my PCP wouldn’t take out a catheter in the office and to go to the ER I realized I could either spend five hours at the bottom of the ER triage or I could take it out myself. I cut the injection port and let the balloon deflate and gently removed it without issue. Within a few hours (and since) I have been urinating just fine.

This story is obviously personal and represents a few things. The physician determined my situation was a side effect of my pain medication and so informed me in such a way as to say “maybe you shouldn’t be taking those medications.” Well, doc, I’d love to not take these medications but without them I can’t function due to Intractable Pain. Maybe if I was on Disability or some other form of I-don’t-work income I could try it and see what happens, but I have a job and a family to support with that job. So firstly it represents bias against people on pain medications, once again. This is a psychological (or maybe even social) side effect of pain medications. Friends and family may shy away from you because you’re on “narcotics” or worse, assume you’re an addict because you’re dependent. I’ve written extensively on how these differ, but the laypeople just fail to understand. There have even been episodes of Intervention-style shows on television wherein a chronic pain patient was accused by a weeping family of abusing their medications and being an addict. A lot of times on these shows it’s true: they’re quite obviously addicts; however, more than once I’ve seen a pain patient taking their medications as prescribed and enduring their side effects only to have this taken as “addiction.” What’s worse is that I’ve seen these legitimate patients forced into rehab more than once because of a bias against medication.

We are sick people. We are sick people with a serious disease. We have pain that’s caused by a disease or is a disease in and of itself. We take medication for that disease, and we withstand the side effects of both that medication and that disease. My only problem is that some of those side effects are man-made, and in a reasonable and educated world should be put to rest. Educate yourselves.

When OxyContin® was released, abusers quickly found that crushing the tablet easily defeated the time-release mechanism, causing all of the oxycodone–meant for slow release over 8-12 hours–to be released into the body at once. This caused a surge in abuse of the drug in the late ’90s and well into later decades as well. Zogenix has announced that the release mechanism for its new hydrocodone formulation is the same currently used by Avinza®, a brand-name of controlled-release morphine. Other drugs using the same release mechanism include Ritalin® LA, Focalin® XR and Luvox® CR. The release mechanism is called Spheroidal Oral Drug Absorption System, or SODAS® and is licensed from Elan Drug Technologies. The SODAS® capsules contain tiny extended-release beads that release too much medication if crushed, chewed, snorted, dissolved, or injected, which will likely lead to a sharp increase in abuse of the drug much in the same manner as OxyContin®. However, for those in pain taking their medication as prescribed, it will be a welcomed addition to the pain pharmacopeia.

Under the US Controlled Substances Act, products containing “no more than 15mg of hydrocodone compounded with an NSAID or APAP” are allowed to be treated as Schedule III drugs, but hydrocodone on its own or in amounts more than 15mg are Schedule II, along with morphine, oxycodone, fentanyl, and most other opioids. Due to an additional law, there are currently no hydrocodone-only drugs on the US market today. This drug would change that.

While only in Phase III trials, the drug remains 3-5 years away.

• Zogenix Press Release
• Elan Drug Technologies Press Release

These people are from a secluded farming town in rural Illinois, near the St. Louis Metro East area. They don’t know anything about anything remotely medical. If their back hurts, they take Benedryl and go to sleep (or become alcoholics). These people only see narcotic analgesics when someone’s passing around some Vicodin along with the joint of marijuana. It only exists for people to take and feel good on. As far as these people are concerned, it might as well be beer for all they care. The first couple of guys told me “we all have aches and pains” and another mocked my “poor little back pain.” I gave them the benefit of the doubt and carefully explained what degenerative facet disease (or “facet syndrome”) is and what it does to you, and what foraminal narrowing (or “foraminal stenosis”) is and what it does to you. I explained it to them calmly, and with no anger. What do you suppose I received in response?

You need to see a doctor. You need help. It’s okay to admit you have a drug problem. Someone will help you. The pain can’t be that bad! The pain is from the withdrawal!

That was a summary of a couple of them… well, the nicer ones, and;

You’re just a junkie that doesn’t want to admit it. No pain can be that bad that you have to go and trick these doctors into giving you drugs all the time. You’re probably crushing them and snorting them or shooting them up. Show us some pictures of your arms, you dirty junkie.

that’s a summary of the vast majority of them. Why is this? Why are people more likely to believe you have a massive drug problem than a simple medical condition? In the world of the chronic pain patients we are used to being looked at with suspicion because of the narcotic analgesics we use every day to control our pain. Most of us are used to this prejudice; however, today I discovered another prejudice that I realized I’ve often been the victim of: not believing the intensity of the pain. I mean, it’s a no-brainer, it happens all the time–sometimes almost every day–but you explain it’s a serious medical condition that employs an entire field of study for specialist physicians and other medical professionals and the seriousness of the matter can usually–at that point–be somewhat understood by the general population. However, there’s always that group of people out there that will never believe you. No matter what’s medically wrong with you, there’s no possible way on earth that you could ever have pain that you can’t just get used to, or grin and bear. Like I said: these are tough farm boys, after all. The only time they’ve seen opioids is when someone’s passing around some Vicodin along with the joint of marijuana. It only exists for people to take and feel good on. As far as these people are concerned, it might as well be beer for all they care. They have no idea that heroin–a drug that has been demonized as to be the worst possible thing anyone can take because they’ll end up on the streets as a junkie–is an opioid, just like that Vicodin they use to relax from time to time. In small rural farm towns like this the drugs of choice tend to be alcohol and tobacco. When it comes to illicit drugs things like cocaine and even (or sometimes especially) meth are soft drugs, go ahead and have fun with them. For the most part, these people would never consider doing heroin–despite the fact they’ve all had a narcotic at some time or another.

The only extremely sad part about this particular conversation is that I went to school with most of these people from ages five through fourteen. Some of us were close friends. These people should know me. These people should be able to be entrusted with the knowledge of my medical condition. A few years out of town, and you’re a dirty junkie. This is why we, as a minority group, tend to not tell most people about our medical problems. It’s not a big deal to tell someone you can’t eat that because you’re diabetic and have to shoot insulin after every meal, but it’s a big horrible thing to tell someone you can’t do something because your pain limits your abilities and you have to take narcotic analgesics after every activity. Suddenly it’s no longer just a medical condition, but you’re a drug addict that’s totally faking it. When no one’s watching, you run and dance and play and do backflips, but when someone’s watching you break out the cane just so people will feel sorry for you.

If only.