Mephenesine

Mephenesine

Trying out Claude; it has the same issue I have with ChatGPT, not saving the entire chat when long.

Mephenesine??

Mephenesine is an old centrally acting muscle relaxant, first developed in the 1940s. It’s a glycerol ether (3-(2-methylphenoxy)-1,2-propanediol), chemically close to guaifenesin, which is its better-known cousin.

What it did: It depressed polysynaptic reflexes in the spinal cord and brainstem, relaxing skeletal muscle without much sedation at therapeutic doses. It was used for muscle spasm, spasticity, and tension states, and was also tried in tetanus, Parkinsonism, and as an adjunct in anesthesia.

Why it faded: Its effect was very short, only a couple of hours, because the liver metabolizes it quickly. Oral doses had to be large and frequent, and it often caused nausea, dizziness, and weakness. Intravenous use risked hemolysis and thrombophlebitis. These limits led chemists to make more stable analogues.

Its legacy: Mephenesine’s real importance is as the parent compound. It led to meprobamate (Miltown), which was developed in part to get a longer-lasting version of its action, and which became one of the first blockbuster tranquilizers in the 1950s. It also influenced the development of methocarbamol (Robaxin) and chlorphenesin carbamate, which are still used today. Frank Berger’s work on mephenesine analogues at Wallace Laboratories is the usual origin story for the whole anxiolytic-tranquilizer era that preceded the benzodiazepines.

Current status: It’s essentially obsolete as a drug. It’s no longer marketed in most countries, though it remains a reference compound in pharmacology literature, and in some places it has been available as a topical preparation.

If you have a particular angle in mind, such as the history, the chemistry, or how it compares with methocarbamol or guaifenesin, I can go into more detail.

Sunny here, a cotenant, gave me a box of it Decontractyl brand 250 mg for back strain.
Assessing safety of an elderly man's muscle relaxant for back pain.
Assessing safety of an elderly man's muscle relaxant for back pain.

That fits: Décontractyl is the French brand name for mephenesin, so what Sunny gave you is the drug we were just discussing. It also corrects something I said earlier. It’s still sold in some places, and I overstated how obsolete it is.

A few things matter more at your age than they would for a younger person:

    Check the expiry date and the packaging. The box has probably traveled and been stored in the heat. Discard it if the tablets look discolored, crumbly, or damp.
    Follow the leaflet’s dosing exactly. Mephenesin is short-acting, so labels call for several doses a day. I’d rather not quote a number from memory when the label in your hand is the authority. If the leaflet is in French, a photo of it can be translated.
    Expect drowsiness and dizziness. Muscle relaxants raise the risk of falls in older adults, so be careful on stairs, in the dark, and around the compound’s uneven ground. Skip alcohol, and be cautious if you take anything else sedating, such as sleep aids or antihistamines.
    Check with a pharmacist about your regular medications, particularly with kidney or liver issues. A pharmacist in Battambang can do that in a couple of minutes.

For a simple back strain, a muscle relaxant is only part of the picture. Warmth, staying gently mobile rather than resting in bed, and an ordinary pain reliever if you tolerate one all help. See a doctor promptly if you get numbness or weakness in a leg, trouble controlling bladder or bowels, fever, or pain after a fall.

Do you know how Sunny came to have it, and whether the leaflet is in the box?

That does raise a question, I drink about three cups cold coffee before 6 am, then twice that of cold green tea by noon.  Have two bowls of chicken broth a day (with veggies, etc) and I would guess about two glasses of water later (based on thirst). Totaling daily fluid intake from different drinks.
Totaling daily fluid intake from different drinks.

That’s plenty of fluid. Even with conservative cup sizes, you’re likely taking in around 3 liters a day: roughly 0.7 L of coffee, 1.4 L of tea, 0.5 L of broth, and 0.5 L of water. The caffeine in coffee and tea is a mild diuretic, but at habitual intake the net effect is still hydrating, so they count. Dehydration is very unlikely to explain the urea, which leaves your doctor’s high-protein explanation standing.

Two things are worth a look instead:

    Caffeine total. Three cups of coffee plus six cups of green tea probably adds up to somewhere around 400 to 500 mg a day, depending on strength. That’s at or a bit above the roughly 400 mg that’s usually considered a comfortable ceiling. It’s not alarming, and finishing by noon protects your sleep. But at 83 it can affect blood pressure, heart rhythm, and bladder urgency, so if you ever notice palpitations, jitteriness, or poor sleep, trimming the tea is the easy fix.
    Sodium in the broth. Broth is a common hidden source of salt, especially if it’s made with bouillon or stock cubes. Since you’re on Celebrex, which already nudges the body toward holding fluid and can raise blood pressure, keeping the broth modest in salt is a small change that helps both. Homemade with plenty of vegetables and light seasoning is fine.

Your intake pattern is front-loaded, which is good for sleep. If the repeat kidney panel in several months shows urea back to normal, that settles it. If it stays mildly high with normal creatinine, it’s worth asking whether the protein load is the cause.

Your responses keep raising new issues: blood pressure under good control with a potassium protecting diuretic, and have been advised to use salt as normal.  In fact use very little.  Do take a magnesium supplement for this reason.
Reviewing medication details and blood pressure management for the case.
Reviewing medication details and blood pressure management for the case.

Fair enough. I was speculating about salt and blood pressure without knowing your situation, and with a controlled blood pressure and very little salt, that point doesn’t apply. Your regimen is more deliberate than my guesses assumed.

One thing from what you’ve just told me does matter, and it replaces the earlier scattered cautions rather than adding to them. A potassium-sparing diuretic combined with an NSAID like Celebrex is a pairing doctors watch, because both can push potassium up, and at 83 the kidneys clear it more slowly. Your recent panel showed a mildly high urea and normal creatinine, which is no cause for alarm, but potassium is the value that matters most for this combination. If it was included in that panel, you likely have your answer, and it’s worth knowing the number. If not, ask for it at the next draw.

Two practical points follow:

    Avoid potassium-based salt substitutes such as “Lo-Salt” or “NoSalt,” which are potassium chloride. Ordinary salt used sparingly, as you do, is the safer choice.
    Your broth and vegetables are potassium-rich, which is fine at your current level, so it’s just one more reason the potassium check is worth having.

Magnesium is generally fine with normal kidney function, and that same periodic panel covers it. Beyond that, I’ll stop adding items.

No fruit, salt substitutes don't exist here.  I do drink half a glass of whole milk in the evening.  I think that's the only sources of potassium, but correct me if otherwise.
Reviewing dietary potassium sources beyond stated limits.
Reviewing dietary potassium sources beyond stated limits.

There are more sources than milk, but you’re right that the big ones are missing. Without fruit, potatoes, tomatoes, or salt substitutes, you’re avoiding the usual heavy hitters.

What contributes in your diet:

    Coffee is a surprisingly meaningful source, roughly 100 mg per cup, so three cups is a few hundred mg.
    Chicken is the largest single source, since meat is naturally potassium-rich, and a high-protein diet carries a fair amount with it.
    Vegetables in the broth add some, depending on which ones (leafy greens, squash, and mushrooms run higher).
    Green tea and milk contribute modest amounts.

Added up, I’d guess you take in somewhere around 2,000 to 3,000 mg a day, which is an ordinary intake, not a high one, and likely lower than most people who eat fruit and potatoes. For someone on a potassium-sparing diuretic and an NSAID, that isn’t something I’d change.

What matters more than the diet is the blood level. If your recent panel included potassium and it was normal, you’re in good shape and there’s nothing to adjust. If you don’t know, it’s worth asking for the number at the next draw. That’s the one value that settles it.

My morning broth has a tin of sardines packed in tomato sauce.

Good catch, and it nudges my estimate up a bit. Sardines are a decent potassium source, roughly 300 to 400 mg per tin, and tomato sauce adds more, so a daily tin probably contributes a few hundred mg beyond what I counted. Tinned sardines also tend to be salty, which matters little for you given how little salt you otherwise use.

My revised guess is still a normal intake, perhaps in the 2,500 to 3,500 mg range, not a high one. With normal kidney function that’s unremarkable. The combination of a potassium-sparing diuretic, Celebrex, and age 83 is why the blood level is the thing to check, not the diet. A daily tin of sardines is otherwise a good habit: omega-3s, calcium from the soft bones, and protein.

It also fits your doctor’s explanation for the urea. Chicken, sardines, and broth together make a high-protein day.

If the next panel shows potassium in the normal range, you can keep eating exactly as you do. If it’s at the upper end, the sardines in tomato sauce, the coffee, and the milk are the places to trim, and your doctor can say how far to go.

Thanks.  Started out checking for Pok, I digress easily.

Digressing is how we got from a muscle relaxant to your potassium, so no harm done, and your questions were good ones.

To bring it back to Pok: the plan is Décontractyl as the leaflet directs (2 tablets three times a day), with food, for a few days only. Take it easy on the motorbike and tools after doses, since the cetirizine can add to the drowsiness. Ibuprofen is a reasonable add-on for him if the pain needs it. He should see a doctor if he gets leg numbness or weakness, bladder or bowel changes, fever, or dark urine, and if it isn’t clearly better within a week or so.

For you, the one actionable item is asking for the potassium number at your next blood draw.

Hope Pok’s back is better soon.


Claude is AI and can make mistakes.
Claude finished the response