Tachycardia theophylline

The nurse can give some of these drug (for example, aminophylline or theophylline) IV, either direct IV or as an IV infusion. When giving theophylline or aminophylline IV, the nurse monitors die patient for hypotension, cardiac arrhythmias, and tachycardia. If a bronchodilator is given IV, the nurse administers it through an infusion pump. The nurse checks die IV infusion site at frequent intervals because these patients may be extremely restless, and extravasation can occur. 

Notify the primary health care provider immediately if any of the following signs of theophylline toxicity develop anorexia, nausea, vomiting, diarrhea, confusion, abdominal cramping, headache, restlessness insomnia, tachycardia, arrhythmias or seizures... 

Albuterol is the preferred bronchodilator for treatment of acute exacerbations because of its rapid onset of action. Ipratropium can be added to allow for lower doses of albuterol, thus reducing dose-dependent adverse effects such as tachycardia and tremor. Delivery can be through metered-dose inhaler (MDI) and spacer or nebulizer. The nebulizer route is preferred in patients with severe dyspnea and/or cough that would limit delivery of medication through an MDI with spacer. If response is inadequate, theophylline can be considered however, clinical evidence supporting its use is lacking. 

The most common side effects of theophylline include dyspepsia, nausea, vomiting, diarrhea, headache, dizziness, and tachycardia. Arrhythmias and seizures may occur, especially at toxic concentrations. 

Patients with cardiovascular disease (including hypertension), diabetes (risk of hyperglycemia), pregnancy (uterine contractions), prostatism, and anxiety disorders are among those who should not take ma huang at any dose. Drug-herb interactions occur with MAOIs (hypertensive crisis), phenoth-iazines (tachycardia, hypotension), (3-blockers (hypertension) and theophylline (increased CNS effects). Of course, caffeine and other stimulants have an additive effect. 

CVS Methylxanthines stimulate the heart and increase the force of myocardial contraction. Tachycardia is more common with theophylline. Cardiac output is increased in CHF patients. 

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. 

Adenosine is a nucleoside that occurs naturally throughout the body. Its half-life in the blood is less than 10 seconds. Its mechanism of action involves activation of an inward rectifier K+ current and inhibition of calcium current. The results of these actions are marked hyperpolarization and suppression of calcium-dependent action potentials. When given as a bolus dose, adenosine directly inhibits atrioventricular nodal conduction and increases the atrioventricular nodal refractory period but has lesser effects on the sinoatrial node. Adenosine is currently the drug of choice for prompt conversion of paroxysmal supraventricular tachycardia to sinus rhythm because of its high efficacy (90-95%) and very short duration of action. It is usually given in a bolus dose of 6 mg followed, if necessary, by a dose of 12 mg. An uncommon variant of ventricular tachycardia is adenosine-sensitive. The drug is less effective in the presence of adenosine receptor blockers such as theophylline or caffeine, and its effects are potentiated by adenosine uptake inhibitors such as dipyridamole. 

Cardiovascular toxicity is also frequently encountered in poisoning. Hypotension may be due to depression of cardiac contractility hypovolemia resulting from vomiting, diarrhea, or fluid sequestration peripheral vascular collapse due to blockade of -adrenoceptor-mediated vascular tone or cardiac arrhythmias. Hypothermia or hyperthermia due to exposure as well as the temperature-dysregulating effects of many drugs can also produce hypotension. Lethal arrhythmias such as ventricular tachycardia and fibrillation can occur with overdoses of many cardioactive drugs such as ephedrine, amphetamines, cocaine, tricyclic antidepressants, digitalis, and theophylline. 

Esmolol Theophylline, caffeine, metaproterenol Short-acting 13-blocker reverses Bi-induced tachycardia and (possibly) -induced vasodilation. Infuse 25-50 vg/kg/min IV. 

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. 

DIRECT THEOPHYLLINE Case report of marked tachycardia when dobutamine was given to a patient already taking theophylline Uncertain Carefully titrate the dose of dobutamine in patients taking dobutamine... 

A 20-year-old man is hospitalized after an asthmatic attack precipitated by an upper respiratory infection and fails to respond in the emergency room to two subcutaneously injected doses of epinephrine. The patient has not been taking theophylline-containing medications for the past 6 weeks. He weighs 60 kg and you estimate that his apparent volume of theophylline distribution is 0.45 L/kg. Bronchodilator therapy includes a 5.6-mg/kg loading dose of aminophylline, infused intravenously over 20 min, followed by a maintenance infusion of 0.63 mg/kg per hour (0.50 mg/kg per hour of theophylline). Forty-eight hours later, the patient s respiratory status has improved. However, he has nausea and tachycardia, and his plasma theophylline level is 24 xg/mL. 

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... 

Antagonists at adenosine receptors should inhibit the action of adenosine, and indeed theophylline increases the dose of adenosine needed for conversion of supraventricular tachycardia (49). 

Xanthines have been given to infants at the risk of sudden infant death sjmdrome or idiopathic apnea of prematurity (see monograph on Theophylline). About 50% of 30 infants treated with caffeine (and 12 of 18 infants treated with theophylline) had significant increases in episodes of gastroesophageal reflux (36). The authors stressed that screening for reflux should precede the administration of caffeine (and theophylline) to infants at the risk of sudden infant death syndrome. As expected, the frequency of adverse effects such as tachycardia and gastroesophageal reflux is lower with lower doses of caffeine for example 2.5 mg/kg qds (SEDA-17,1). 

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). 

Theophylline clearance was reduced by levofloxacin plus clarithromycin in a 59-year-old Japanese man, who had stimulation, insomnia, and tachycardia due to theophyl-hne toxicity (39). 

Orciprenaline is somewhat beta2-selective compared with isoprenaline, but is by no means free of cardiac effects (1). Individual susceptibility to these varies, but it would seem that about one individual in 10 will experience tachycardia after usual therapeutic doses. At normal doses (for example 20 mg qds) jitteriness and nervousness are not uncommon, and about one patient in 12 suffers from cramps or numbness in the extremities. Lactic acidosis has been described in one patient as a result of concomitant use of orciprenaline, theophylline, and glucocorticoids. Other susceptibility factors and interactions are as for isoprenaline. 

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. 

Theophylline crosses the placenta, resulting in potentially dangerous serum theophylline concentrations in the neonate (SEDA-5, 3). This is of practical importance, since 1.3% of pregnant women have asthma. Fetal tachycardia has been observed when maternal blood concentration... 

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. 

A 59-year-old Japanese man taking theophylline for emphysema had stimulation, insomnia, and tachycardia owing to theophylline toxicity after he also took levofloxacin and clarithromycin (76). His theophylline clearance returned to normal and his symptoms resolved after withdrawal of levofloxacin, while clarithromycin was continued. 

Levine JH, Michael JR, Guarnieri T. Multifocal atrial tachycardia a toxic effect of theophylline. Lancet 1985 1(8419) 12-14. 

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. 

In acute overdose, peak serum levels > 100 pg ml may be predictive of arrhythmias and seizures. The use of sustained-release formulations and the presence of pharmacobezors in the gut may make it difficult to determine peak serum levels. Sinus tachycardia is the most common cardiac sign of theophylline toxicity. Ventricular and supraventricular tachycardia, ectopic beats, hypotension, and cardiac arrest may occur. Metabolic acidosis, hypokalemia, hypercalcemia, and hyperglycemia may be seen. Tremulousness and agitation frequently occur. Intractable seizures may occur in severe intoxications, probably secondary to adenosine receptor antagonism in the brain. Onset of seizures is a poor prognostic indicator. Persistent vomiting is commonly seen and may interfere with attempts at therapy. 

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