Caffeine and sodium benzoate Injection

It is very important that your doctor check your progress closely while you are receiving caffeine and sodium benzoate and to see if it is working properly.

Using large doses of caffeine and sodium benzoate may cause unwanted effects. Tell your doctor right away if you have a headache, anxiety, fast, pounding, or uneven heartbeat, ringing in the ears, or tingling in the hands and feet.

Before you have any medical tests, tell the medical doctor in charge that you are taking caffeine and sodium benzoate. The results of some tests may be affected by caffeine and sodium benzoate.

Do not take other medicines unless they have been discussed with your doctor. This includes prescription or nonprescription (over-the-counter [OTC]) medicines and herbal or vitamin supplements.

Caffeine is pharmacologically similar to the other xanthine drugs, such as theobromine and theophylline; however, these three agents differ in the intensity of their actions on various structures. Caffeine's CNS and skeletal muscle effects are greater than those of the other xanthines. In all other areas, theophylline has greater activity than caffeine, although some studies report that caffeine has greater diuretic effect than theobromine. The increased levels of intracellular cyclic-AMP mediate most of caffeine's pharmacologic actions. Caffeine competitively inhibits phosphodiesterase, the enzyme that degrades cyclic 3'- 5' adenosine monophosphate. Caffeine stimulates all levels of the CNS. Caffeine's cortical effects are milder and of shorter duration than those of the amphetamines. In slightly larger doses, caffeine stimulates medullary vagal, vasomotor and respiratory centers, promoting bradycardia, vasoconstriction, and increased respiratory rate.

Caffeine produces a positive inotropic effect of the myocardium and a positive chronotropic effect at the sinoatrial node, causing transient increases in heart rate, force of contraction, cardiac output and heart work. In doses greater than 250 mg, the centrally mediated vagal effects of caffeine may be masked by increased sinus rates; tachycardia, extrasystoles, or other major ventricular arrhythmias may result.

Caffeine constricts cerebral vasculature. In contrast, the drug directly dilates peripheral blood vessels, decreasing peripheral vascular resistance. The effect of this decrease in peripheral vascular resistance (and possibly that of vagal cardiac stimulation) on blood pressure is offset by increased cardiac output (and possibly stimulation of the medullary vasomotor area). The overall effect of caffeine on heart rate and blood pressure depends on whether CNS or peripheral effects predominate. Therapeutic doses of caffeine increase blood pressure only slightly.

Caffeine stimulates voluntary skeletal muscle, increasing the force of contraction and decreasing muscular fatigue. The drug also stimulates gastric acid secretion from parietal cells. Caffeine increases renal blood flow and glomerular filtration rate and decreases proximal tubular reabsorption of sodium and water, resulting in mild diuresis.

Caffeine stimulates glycogenolysis and lipolysis, but increase in blood glucose and in plasma lipids are insignificant in normal patients. Tolerance may develop to the diuretic, cardiovascular, and CNS effects of caffeine.

Pharmacokinetics

Caffeine is rapidly distributed throughout the body tissues, readily crossing the placenta and blood-brain barrier. Approximately 17% of the drug is bound to plasma proteins. Caffeine has approximately a half-life (T ½) of 3-4 hours in adults. In adults, the drug is rapidly metabolized in the liver to 1-methyluric acid, 1-methylxanthine and 7-methylxanthine. Caffeine and its metabolites are excreted primarily by the kidneys.

None known.

Acute toxicity involving caffeine has been reported rarely. Mild delirium, insomnia, diuresis, dehydration, and fever commonly occur with overdosage. More serious symptoms of overdosage include cardiac arrhythmias and clonic-tonic convulsions. In adults, IV doses of 57 mg/kg of body weight and oral doses of 18.50 grams have been fatal. In one 5-year-old patient, death occurred following oral ingestion of approximately 3 grams of caffeine. Convulsions may be treated with IV administration of diazepam or a barbiturate such as pentobarbital sodium.