Soap from castor oil: an experiment

Castor oil appears as an ingredient in many older enema recipes and even a few current ones, but people who have tried it will know it is a disappointment. This might seem surprising, as castor oil taken orally can be a startlingly effective laxative. But in fact it only works as a laxative after it has been broken down by pancreatic enzymes in the small intestine. This liberates ricinoleic acid, which is highly irritating to the gut. But in the colon the enzymes are not present, so oil introduced that way remains undigested and inactive, working only as a lubricant.

In some older medical literature the digestion of castor oil (and other oils) is described in terms of saponification, e.g. http://chestofbooks.com/health/materia-medica-drugs/Pharmacology-Therapeutics-Prescription-Writing/index.html from 1918: ‘[Castor] oil is saponified in the small intestine to form glycerin and sodium ricinoleate, a soap which is much more irritant than Castile soap to the intestinal mucous membrane.’ This conception seems to be abandoned today. However, it suggested to me the possibility of making a soap from castor oil (i.e. sodium ricinoleate), and trying it in an enema. Some googling revealed reports on this soap by at least two soapmakers who have made it while studying single-oil soaps. (Most soaps are made from mixtures of oils, which sometimes include a low percentage of castor.)

I made a batch of castor oil soap over Easter, and it was ready to use after a couple of days. 500 grams of castor oil produced a bit over 700 grams of soap, of which close to 25% was water. The weight declined steadily due to evaporation, reaching ~640 g by last Saturday. I decided to use one-eighth of the batch in an enema, reasoning that it would represent approximately a 65 ml dose of castor oil. I cut 80 grams of soap into ~5 g chunks which dissolved quite readily in hot water, then made up the water to 2.5 litres, my usual volume. I injected it slowly at 42–43°C with a double balloon nozzle and a Higginson syringe, one bulbful or ~80 ml every 30–40 seconds, waiting for any cramps or urges to clear before proceeding. Cramping began within five minutes, it took 11 minutes to inject 800 ml, at the end of 20 minutes I had only taken 1200 ml and the cramps were unremitting. I decided this was enough for a first try and expelled. Expulsion was quick and thorough, finished in less than 10 minutes, with no ‘repeats’, but I was left with a bellyache that faded over an hour or so.

I have two soaps that I regularly use for enemas: a liquid Castile soap and a tallow and coconut oil soap sold in flake form as a laundry soap. The latter is a little stronger, and I generally take 125 g in 2.5 litres of water. I gather this is a stronger solution than most people use, but the castor oil soap solution worked much more strongly still. I concluded I should probably use a weaker solution, or at least inject it quicker to get it in before the cramping begins in earnest.

Nine hours later I thought I would use up the rest of the solution. Unlike more familiar solid soaps, the solution had not set on cooling to room temperature. I reheated it to the low 40s C and injected it this time as rapidly as possible, held for five minutes and expelled. Results were similar to the first time, only the bellyache lasted longer, a couple of hours.

Will I do this again? Well, I’ve got at least seven more doses of the soap left (more if I use a weaker solution). I certainly wouldn’t want to use it for every enema, but I can see myself taking it again when I feel like something a bit out of the ordinary.

Actualy the idea that Castor Oil is saponified in the small bowel is still very much alive and well. I have a 1997 book on laxatives that says the same thing. However research has also revealed that the effects of Castor oil are not really the result of irritation produced by Sodium and Potassium Ricinoleate. The mechanism turns out to be a lot more complex.

Look at this report upon the action mechanism of castor oil in the human body:

http://www.mpg.de/5808639/receptor_castor_oil

Yes, I have seen this research, including the original report at http://www.ncbi.nlm.nih.gov/pubmed/22615395 , and that was in fact the reason I said the notion of CO acting through its saponification products had been abandoned. But I didn’t quote it as it wasn’t directly relevant to my post (which was pretty long already). — Be that as it may, the saponification products are pretty powerful in themselves!

I have continued experimenting with this soap—still with the first batch, which has now dried to the point where its moisture content is in equilibrium with the air, so it is no longer losing weight. The 80g I used for the enemas I described in my first post would be equivalent to about 65g of the dried soap. It is very hard and somewhat brittle. And it makes brutally strong enemas, so I have reduced the strength of the solutions I use.

Today I tried 45g of the castor oil soap plus 45g of my usual laundry soap product [made from tallow and coconut oil]. I regularly take 125g of the laundry soap in 2.5 litres of warm water, but this 45g+45g mixture was a good deal stronger than that, and I only took a little more than 2 litres over 15 or so minutes before I called it enough and expelled. Expulsion took about 45 minutes and was complete (no peeing afterwards).

I’m going to try varying proportions of the castor oil and commercial soaps, and when I’ve found a mix that I like I’ll make my own enema soap to that formula. I used to be quite interested in chemistry as a boy, though I never studied it at an advanced level, and I’m enjoying the process of reconnecting with that early interest.

I came across this the other day, showing that I am far from the first to explore the potential of castor oil soap:

‘Castor-Oil Soap

‘By F. M. RIMMINGTON.

‘It is somewhat remarkable that our present English pharmacy has no pure medicinal soap possessing any characteristic property or medicinal activity. The ordinary Castile soap, being that which is commonly used for that ordered by the Pharmacopoeia, can scarcely be considered a satisfactory article when we consider its composition and the mode of its manufacture. Having recently had occasion to direct my attention to this subject, it occurred to me that castor-oil offered some advantages, and would yield a soap possessing qualities very desirable in an article which so frequently formed the medium or adjunct for administering other active remedies. On putting this idea into practice, I found that a soap prepared from this oil has rather marked qualities, but my opportunities do not afford me the means of properly testing its medicinal properties. I believe it will be found that it has sufficient aperient power to relax the bowels when taken consecutively for several days, but I believe its greatest value will be found as an adjunct to other aperients. This at least is the result I have arrived at. It is, of course, well known that the purgative principle of castor-oil has been ascribed by Soubeiran to the existence of a supposed oleo-resin, and that the ricinoleic acid is extremely acrid. I find when the oil is saponified that this acrid principle is either entirely or partially liberated, and does not continue masked as it is in the oil in its natural state, nor neutralized, as might be expected, by the alkali. It is to this fact, I think, we must look for any active property this soap may possess; and here I must leave the matter for the further investigation of the medical and pharmaceutical professions. The physical properties of the soap are in its favor for use in medicine. It has a clean yellowish-white color, is free from smell; it soon becomes dry, hard and is easily powdered; it has no tendency to soften or deliquesce on exposure to the air. In proof spirit it makes a perfectly clear and colorless solution, with only a little sediment. I shall forward a specimen to the Society for the inspection of those who may feel interested.—London Pharm. Journ., February 25, 1871.’

It seems that Mr Rimmington was considering castor oil soap as an oral remedy, but it is far from clear how he conducted his investigations, or what exactly he found (‘I believe it will be found …’, ‘This at least is the result I have arrived at’ [how?], etc.). He is right—or rather, the French pharmacist Soubeiran whom he quotes is right—in implying that ricinoleic acid is very ‘acrid’: it has a much lower pH than other fatty acids. The reference to an ‘oleoresin’, however, is wide of the mark. His description of the soap matches my own, except for the smell: mine smells very distinctly of castor oil. He may have used a more highly refined oil. And I haven’t tried dissolving mine in proof spirit.

Felix Marsh Rimmington was apparently a significant name in British pharmacy. There is a Rimmington’s Pharmacy in Bradford, established by F. M. Rimmington in 1842 and still operating! A company F.M. Rimmington & Son Ltd. was incorporated in 1901 and only recently dissolved, in 2008; but I am doubtful if it could have been founded by the same man who established the pharmacy 59 years earlier.

I have continued experimenting with the batch of castor oil soap I made last Easter, using smaller quantities each time. Previously I have combined it with other hard soaps (sodium soaps), but yesterday I tried adding it to the liquid soap I use for about two out of three enemas. I mixed just 10 grams of the castor oil soap and 80mL of liquid Castile soap with 2.5L of warm water and injected it slowly with a Higginson pump and double balloon nozzle, around one bulbful every 30 seconds. The dull bellyache that seems to be the hallmark of castor oil soap started up after ten minutes or so. By the time the whole 2.5L was in I was having pretty strong cramps and urges. As usual, expulsion was fairly quick, no more than 10 minutes, and complete, with no return trips. This seems like a very viable recipe.

10g of soap would correspond to under 10mL of castor oil, which taken by mouth wouldn’t have a very strong effect at all. However, the oil has to be metabolised, which takes time, and the metabolites (ricinoleic acid and/or sodium and potassium ricinoleate) would make their way to the colon over time in fairly small increments. So it makes sense that the effect in the colon of a less than 10mL oral dose of oil is much weaker than that of dumping 10g of castor oil soap in the colon in the form of an enema.

Some cheap high-quality castor oil can be purchased from https://oilscenter.com/essential-oils, but I honestly think that would be better for you just to get some soap, they offer a wide range of products and I really like to buy from them. Actually, they also sell soap bases but I've never tried to make a soap with it myself.