There are also many drug interactions . Patients must read in detail the enclosed data sheet(s) of the medicine. For example, the azole antifungals such as ketoconazole or itraconazole can be both substrates and inhibitors of the P-glycoprotein , which (among other functions) excretes toxins and drugs into the intestines.  Azole antifungals also are both substrates and inhibitors of the cytochrome P450 family CYP3A4 ,  causing increased concentration when administering, for example, calcium channel blockers , immunosuppressants , chemotherapeutic drugs , benzodiazepines , tricyclic antidepressants , macrolides and SSRIs .
Studies on the salicylic content of foods are sparse and have produced distinctly different results, creating controversy.  Possible causes for the discrepancies include uncontrolled and often unreported factors such as cultivation area, crop species, and harvest methods, as well as inherent issues with the studies such as poor extraction and measurement procedures and limited or low-accuracy equipment. A recent study using best practice measurement methodology significantly reduced intra-sample measurement variability but has not yet been replicated or extended. 
Buying Castor Oil
Any oil that enters your body either orally or through the skin needs to be of the highest quality. Castor oil is no different. Check your local health food store for cold-pressed castor oil.
In his readings, Cayce attributed several actions to castor oil. Most were in one way or another related to the body's lymphatic system. However, he also alluded to the idea that castor oil has a vibrational quality that helps harmonize and promote healing within body cells. Based on statements like these, many people labeled his psychic readings as quackery. As we gain new knowledge about the workings of the human body, however, these explanations don't seem so far fetched.
Dr. Johanna Budwig has related much of the healing properties of flax oil to its unique chemical bonds that vibrate at the same frequency as the wavelengths of sunlight. She feels the essential fatty acids in flax oil have the ability to absorb and store the energy from sunlight. It's possible that the special bonding in castor oil's unique ricinoleic acid works in a somewhat related method.
Regardless of exactly how it works, I think you'll be more than satisfied when you experience the amazing feats that can be accomplished with the simple oil of the castor bean. Centuries ago the castor bean plant was referred to as the "Palma Christe." It was called this because the shape of the plant's leaves were thought to resemble the palm of Christ. Knowing the healing power of this plant, the name may be one of the most accurate descriptions ever.