Caffeine arrhythmias

Animal studies indicate that trichloroethylene can sensitize the heart to epinephrine-induced arrhythmias. Other chemicals can affect these epinephrine-induced cardiac arrhythmias in animals exposed to trichloroethylene. Phenobarbital treatment, which increases the metabolism of trichloroethylene, has been shown to reduce the trichloroethylene-epinephrine-induced arrhythmias in rabbits (White and Carlson 1979), whereas high concentrations of ethanol, which inhibits trichloroethylene metabolism, have been found to potentiate trichloroethylene-epinephrine-induced arrhythmias in rabbits (White and Carlson 1981). These results indicate that trichloroethylene itself and not a metabolite is responsible for the epinephrine-induced arrhythmias. In addition, caffeine has also been found to increase the incidence of epinephrine-induced arrhythmias in rabbits exposed to trichloroethylene (White and Carlson 1982). 

White JF, Carlson GP. 1982. Epinephrine-induced cardiac arrhythmias in rabbits exposed to trichloroethylene potentiation by caffeine. Fundam Appl Toxicol 2 125-129. 

A cnp of coffee can contain 50-150 mg of caffeine, and cola drinks can have 35-55 mg. Theophiline,l,3-dimethylxanthine, a principal, characteristic alkaloid of tea, and theobromine, 3,7-dimethylxanthine (23.3.19), a principal alkaloid of cocoa, are among a number of methylxanthines. In small doses, caffeine is a relatively weak psychostimulant and is used for increasing awareness as well as for relieving headaches associated with blood flow disorders of the brain. Caffeine has a stimulatory effect on the respiratory and vasomotor centers, and it stimnlates centers of the vagus nerve. It has a direct stimulatory effect on the myocardium, and in large doses can cause tachycardia and arrhythmia. 

At high doses, caffeine can cause arrhythmias, palpitations, and tachycardia. 

Alterations in the serum potassium level are hazardous because they can result in cardiac arrhythmias. Drugs that may cause hyperkalemia despite normal renal function include potassium itself, 13 blockers, digitalis glycosides, potassiumsparing diuretics, and fluoride. Drugs associated with hypokalemia include barium, 13 agonists, caffeine, theophylline, and thiazide and loop diuretics. 

Caffeine CNS stimulant Oral from coffee, tea, other beverages Increased alertness decreased fatigue improved work capacity Sleep disturbances irritability nervousness cardiac arrhythmias See Chapter 26... 

Toxicants may have three effects on pulse rate bradycardia (decreased rate), tachycardia (increased rate), and arrhythmia (irregular pulse). Alcohols may cause either bradycardia or tachycardia. Amphetamines, belladonna alkaloids, cocaine, and tricyclic antidepressants (see imi-primine hydrochloride in Figure 6.12) may cause either tachycardia or arrhythmia. Toxic doses of digitalis may result in bradycardia or arrhythmia. The pulse rate is decreased by toxic exposure to carbamates, organophosphates, local anesthetics, barbiturates, clonidine, muscaric mushroom toxins, and opiates. In addition to the substances mentioned above, those that cause arrhythmia are arsenic, caffeine, belladonna alkaloids, phenothizine, theophylline, and some kinds of solvents. 

Adverse effects Moderate doses of caffeine cause insomnia, anxiety, and agitation. A high dosage is required to show toxicity, which is manifested by emesis and convulsions. The lethal dose is about 10 g for caffeine (about 100 cups of coffee), which induces cardiac arrhythmias death from caffeine is thus highly unlikely. Lethargy, irritability, and headache occur in users who have routinely consumed more than 600 mg of caffeine per day (roughly 6 cups of coffee/day) and then suddenly stop. 

Caffeine (particularly more than five cups a day) increases the risk of insomnia (therefore avoid it in patients on tranquillizers, hypnotics and antidepressants) and may cause arrhythmias in susceptible patients,... 

Purine receptors Adenosine, AMP, ADP and ATP can act extracellularly as hormones or transmitters, too In particular, adenosine receptors that occur in the heart, the brain, and the lung are the targets of theophylline and caffeine. Adenosine itself is being used for the treatment of a special type of cardiac arrhythmia. 

For events in which output of energy is explosive (100 m sprint) stimulants, e.g. amphetamine, bro-mantan, carphendon, cocaine, ephedrine and caffeine (> 12 mg/1 in urine). Death has probably occured in bicycle racing (continuous hard exercise with short periods of sprint) due to h3q>erthermia and cardiac arrhythmia in metabolically stimulated and vaso-constricted subjects exercising maximally under a hot sun. 

Breast-fed infants may become sleepless and irritable if there is high maternal intake. Fetal cardiac arrhythmias have been reported with exceptionally high maternal caffeine intake, e.g. 1.51 cola drinks/day. 

Increased levels of astemizole increased risk of cardiac arrhythmia Increased levels of benzodiazepine Increased levels of theophylline or caffeine... 

Cannon ME, Cooke CT, McCarthy JS. Caffeine-induced cardiac arrhythmia an unrecognised danger of healthfood products. Med J Aust 2001 174(10) 520-1. 

Consuming more than 1,000 mg of caffeine a day increases the risk of experiencing even more severe toxic symptoms, including muscle txvitching, rambling flow of thought and speech, cardiac arrhythmia, periods of inexhaustibility, and psychomotor agitation (American Psychiatric Association, 1987). Other symptoms that have... 

It may be possible for some individuals simply to reduce their dosage of caffeine rather than discontinue it altogether. Others may be particularly sensitive to the drug, and they may not be able to handle even reduced intake of caffeine. Patients with cardiovascular disease, especially arrhythmias, should refrain totally, as should people with prior stroke or transient ischemic attacks. Peptic ulcer patients and those with bipolar mood disorder and schizophrenia should be encouraged to avoid caffeine altogether. 

Some investigations into caffeine-related health issues are inconclusive. Studies have shown no correlation between caffeine intake and increased risk of osteoporosis or increased risk of spontaneous abortion. There is no conclusive evidence linking caffeine intake (as coffee) with bladder, pancreatic, breast, or colon cancer. There is also no conclusive evidence that moderate caffeine intake contributes to heart disease or heart arrhythmias however, one study has shown that relatively high coffee consumption elevates blood levels of homocysteine (an amino acid)—a situation that may contribute to heart attack or Alzheimer s disease. There is continuing con-... 

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