Transdermal Absorption of Castor Oil

With the current high level of interest in patches to deliver drugs across the skin, the concept of external applications for delivery of medicinal substances is becoming widely accepted. This study evaluated the potential for transdermal absorption of castor oil, a treatment modality recommended by Edgar Cayce. Specific epoxydicarboxylic acids are known to be excreted via the urine when castor oil is administered orally. Comparison of the amounts of these substances in the urine of subjects given oral and transdermal administrations of castor oil may provide evidence of transdermal absorption of castor oil and provide clues to its metabolism in the system. Three volunteers were given castor oil via abdominal hot pack and oral administration. Urine samples were collected before and after the interventions. Oral administration of castor oil resulted in high levels of excretion of the epoxydicarboxylic acids in all the subjects, results similar to a previous study. In contrast, the level of urinary epoxydicarboxylic acids in the external application (abdominal pack) sessions did not vary greatly from the relatively low endogenous levels of these molecules that are normally present. If the castor oil was absorbed through the skin and metabolized in the system, it did not have the effect of significantly increasing the excretion of the specific metabolic byproducts associated with ingestion of castor oil. The implications of these findings are discussed and directions for future research are considered.