Peroral Administration of Vitamin B₆ (Pyridoxine Hydrochloride) in the Treatment of Radiation Sickness

A serious complication of radiation therapy is the frequent occurrence of nausea and vomiting, commonly called radiation sickness. At times this becomes so severe that it necessitates temporary or even permanent cessation of a projected course of therapy.

Since the individual reaction to radiation is variable, one cannot predict which patient will develop radiation sickness. Empirically, the determining factors should be the size of the port, dosage, and region treated, but such is not always the case. The amount of roentgen absorption necessary to produce and maintain radiation sickness has not been determined and is probably not a constant factor. It has been our experience, however, that ill effects seldom follow treatment of peripheral ports, while irradiation of the torso, particularly the abdomen, usually produces some nausea and vomiting. We have not noted any definite relationship between nutritional status and the ability to tolerate radiation therapy.

Many theories have been advanced as to the cause of radiation sickness, and many therapeutic measures have been tried, none of which has proved entirely satisfactory. The vitamin B group has been used extensively, and with not inconsiderable success. The use of vitamin B₆ by Willis et al. (1) in the nausea and vomiting of pregnancy and the uniformly good result obtained by Maxfield, McIlwain, and Robertson (2) from the intravenous administration of this drug in the treatment of radiation sickness prompted our present investigation. The intravenous route of administration, although effective, is cumbersome, time consuming, and less suitable to a large clinic than the peroral route. This paper is a preliminary report on the use of vitamin B₆ (pyridoxine hydrochloride) given per os to a series of 50 patients who developed nausea or vomiting, or both, during radiation therapy, or had had these symptoms during a previous course of treatment. Otherwise the patients were unselected.

After preliminary investigation, it was found that the best results were obtained when 75 to 100 mg. doses were given one half hour before meals, three or four times a day. The larger doses were chosen when treatment was given to the abdomen or chest, the smaller when treatment was directed to the pelvis or peripheral ports, such as the axilla, neck, or groin. If the dose was less than 75 mg., the maximal benefit was not obtained. Occasionally, when the drug was not retained because of vomiting, the oral dose was supplemented by intravenous medication.

Table I shows the results of peroral administration of vitamin B₆ in the 50 cases. Unless otherwise specified, the irradiation factors were: 250 kv., 1.5 mm. copper filter, 50–70 cm. target-skin distance.