Theophylline tachycardia caused

These cases of interactions of aminophylline with macro-lide antibiotics illustrate that serious, even fatal, adverse effects can occur when possible interactions are not considered. In both cases, experienced physicians prescribed appropriate antimicrobial drugs, but omitted to consider the possibility of interactions with aminophylline, and failed to reduce the dose of aminophyUme or to measure theophylline concentrations. In the first case the development of tachycardia, hypokalemia, acidosis, vomiting, and convulsions can be explained on the basis of theophylline toxicity caused by ciprofloxacin, while in the second the anxiety, tremor, and cardiac arrests could all have resulted from an interaction of aminophylline and erythromycin. These cases add to an extensive literature that emphasizes the potential for interaction between aminophylline and drugs metabolized by CYP1A2. 

Factors that commonly precipitate cardiac arrhythmias include hypoxia, electrolyte disturbances (especially hypokalemia), myocardial ischemia, and certain drugs (Table 34-1). For example, theophylline can cause multifocal atrial tachycardia, while torsades de pointes can arise not only during therapy with action potential-prolonging antiarrhythmics but also with other drugs, including erythromycin (see Chapter 46) pentamidine (see Chapter 40) and some antipsy-chotics, notably thioridazine (see Chapter 18). 

B. Reversal of hypotension and tachycardia caused by excessive beta-adrenergic activity resulting from theophylline or caffeine overdose. 

Side effects are usually associated with the increasing serum concentration of theophylline and includes nausea, vomiting, headache, insomnia, tachypnea, epigastric pain, palpitation, hypotension, irritability. Higher doses can cause persistent vomiting, cardiac arrhythmias, intractable seizures, tachycardia. Other side effects include alopecia, hyperglycemia, inappropriate ADH syndrome, rash. 

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. 

Sympathomimetic syndromes include tachycardia, hypertension, hyperthermia, sweating, mydriasis, hyperreflexia, agitation, delusions, paranoia, seizures and cardiac arrhythmias. These are commonly caused by amphetamine and its derivatives, cocaine, proprietary decongestants, e.g. ephedrine, and theophylline (in the latter case, excluding psychiatric effects). 

Cardiovascular system. Both caffeine and theophylline directly stimulate the myocardium and cause increased cardiac output, tachycardia and sometimes ectopic beats and palpitations. This effect occurs almost at once after i.v. injection and lasts half an hour. Theophylline contributes usefuUy to the relief of acute left ventricular failure. There is peripheral (but not cerebral) vasodilatation due to a direct action of the drugs on the blood vessels, but stimulation of the vasomotor centre tends to counter this. Changes in the blood pressure are therefore somewhat unpredictable, but caffeine 250 mg (single dose) usually causes a transient rise of blood pressure of about 14/10 mmHg in occasional coffee drinkers (but has no additional effect in habitual drinkers) this effect can be used advantageously in patients with autonomic nervous system failure who experience postprandial hypotension (2 cups of coffee with breakfast may suffice for the day). In occasional coffee drinkers 2 cups of coffee (about 160 mg caffeine) per day raise blood pressure by 5/4 mmHg. Increased coronary artery blood flow may occur but increased cardiac work counterbalances this in angina pectoris. 

Elevated theophylline levels may result, possibly causing tachycardia, palpitations, irritability, and tremor... 

Mexiletine reduces the clearance of theophylline, and this combination has been reported to cause ventricular tachycardia (52). A similar interaction tvith caffeine has been reported (53). 

Salbutamol has additive effects with theophylline, which can potentiate the hypokalemic effect (SEDA-17, 164). In 14 healthy volunteers, theophylline increased salbu-tamol-induced hjrpokalemia and in some individuals there was profound hypokalemia (less than 2.5 mmol/1) (35). Combining theophylline with salbutamol increased the tachycardia resulting from the salbutamol infusion. Salbutamol infusion caused a fall in diastolic and a rise in systolic blood pressure, which was not altered by theophylline. 

Ephedra has been closely linked to methamphetamine production. There are movements In many localities to outlaw the herb. There are many drug interactions with Ma huang. )9-BI(K kcrs may enhance the sympathetic effect and cause hypertentiion. MAOIs may interact with ephedra to cause hypertensive cri.si.s. Phcnothiaz.ines might block the or effects of ephedra, causing hypotension and tachycardia. Simultaneous use of theophylline may cau.se GI and CNS effects. In pregnancy, ephedra is absolutely contraindicated (uterine stimulation). Persons with heart disease, hypertension, and diabetes should not take ephedra. 

The rise in heart rate (Fig. 4b) observed within the first minutes of infusion is probably best described as a reflex tachycardia. The same phenomenon has also been observed with the Aj -selective full agonist CGS 21680. The latter compound, however, reached peak values (data not shown) as high as 550 beats per minute (bpm), contrasting to the mean highest value for theophylline-7-riboside of 425 bpm. CPA in the same experimental setup caused a decrease in heart rate to as low as 150 bpm. Thus, theophylline-7-riboside behaved as a partial agonist on parameters that are strictly A, receptor mediated (heart rate) or both A and Aj (mean arterial pressure). In conclusion, theophylline-7-riboside, developed from the antagonist theophylline, may be a useful tool as a partial agonist for adenosine receptors. Its low affinity is a potential drawback, which warrants the development of other compounds for which theophylline-7-riboside may be a lead. 

Concomitant treatment with fluvoxamine may cause a marked elevation in plasma theophylline levels associated with signs of theophylline toxicity, including ventricular tachycardia, anorexia, nausea, and seizures. 

Isoetharine Is dispensed as a solution only for Inhalation administration to treat reversible bronchospasm of asthma. It has fallen Into relative disuse, because with high doses, there Is a significant Incidence of cardiovascular (pi-receptor) adverse effects and It has a low p2-receptor potency compared to newer p2-selectlve agonists. It has a 2- to 4-mlnute onset of action when Inhaled and a duration of action of 3 hours. Isoetharine has adverse effects similar to those of EPI, Including palpitations, tachycardia, nausea and vomiting, dizziness, tremor, and headache. Isoetharine may cause decreased levels of theophylline when coadministered. Cardiovascular effects are a concern when Isoetharine Is taken with other asthma drugs. 

Beta-adrenergic syndrome. Beta-2-mediated vasodilation may cause hypotension. Tachycardia is common. (Examples albuterol, metapro-terenol, theophylline, and caffeine.)... 

A. To control excessive sinus tachycardia or ventricular arrhythmias caused by catecholamine excess (eg, theophylline or caffeine), sympathomimetic drug intoxication (eg, amphetamines, pseudoephedrine, or cocaine), or excessive myocardial sensitivity (eg, chloral hydrate, freons, or chlorinated and other hydrocarbons). 

Unknown. Caffeine alone can cause headache, tachycardia, and jitteriness, and individuals vary in their susceptibility to these effects. The effects of caffeine, theophylline, and theobromine in rats were enhanced by MAOIs. ... 

The manifestations displayed by a patient with HF will vary in severity depending on the patient s current state of health and other chronic illnesses that affect the metabolic demands on the patient. Side effects from some treatments for other conditions could affect the symptoms of HF manifested for example, a patient taking a pulmonary drug such as theophylline might experience tachycardia, which stresses the heart and causes the heart to fail with accompanying symptoms. 

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