Long-term antiarrhythmic therapy. Problem of low drug levels and patient noncompliance

Atrial Fibrillation in Inherited Channelopathies

Atrial fibrillation (AF), the common sustained arrhythmia in clinical practice, has major public health implications due to its associated morbidity and increased mortality. The AF epidemic is due to the burgeoning elderly population and the identification of novel risk factors, for example, genetics. Since the diagnosis of AF has a major impact on the clinical assessment and management of patients with inherited arrhythmia syndromes, improved understanding of the cause and pathogenesis of AF has provided important insights into the underlying pathophysiological mechanisms of this common arrhythmia and identified potential mechanism-based therapies.

Use of antiarrhythmic drug therapy and clinical outcomes in older patients with concomitant atrial fibrillation and coronary artery disease

AIMS

Atrial fibrillation (AF) and coronary artery disease (CAD) are common in older patients. We aimed to describe the use of antiarrhythmic drug (AAD) therapy and clinical outcomes in these patients.

METHODS AND RESULTS

We analysed AAD therapy and outcomes in 1738 older patients (age ≥65) with AF and CAD in the Duke Databank for cardiovascular disease. The primary outcomes were mortality and rehospitalization at 1 and 5 years. Overall, 35% of patients received an AAD at baseline, 43% were female and 85% were white. Prior myocardial infarction (MI, 31%) and heart failure (41%) were common. Amiodarone was the most common AAD (21%), followed by pure Class III agents (sotalol 6.3%, dofetilide 2.2%). Persistence of AAD was low (35% at 1 year). After adjustment, baseline AAD use was not associated with 1-year mortality [adjusted hazard ratio (HR) 1.23, 95% confidence interval (CI) 0.94-1.60] or cardiovascular mortality (adjusted HR 1.27, 95% CI 0.90-1.80). However, AAD use was associated with increased all-cause rehospitalization (adjusted HR 1.20, 95% CI 1.03-1.39) and cardiovascular rehospitalization (adjusted HR 1.20, 95% CI 1.01-1.43) at 1 year. This association did not persist at 5 years; however, these patients were at very high risk of death (55% for those >75 and on AAD) and all-cause rehospitalization (87% for those >75 and on AAD) at 5 years.

CONCLUSIONS

In older patients with AF and CAD, antiarrhythmic therapy was associated with increased rehospitalization at 1 year. Overall, these patients are at high risk of longer-term hospitalization and death. Safer, better-tolerated, and more effective therapies for symptom control in this high-risk population are warranted.

Buccal transport of flecainide and sotalol: effect of a bile salt and ionization state

Patients with infrequent attacks of supraventricular arrhythmia may benefit from self administration of antiarrhythmic drugs on an 'as required' basis. The oral cavity is easily accessible and the potential for rapid absorption exists. The effects of ionization state and sodium glycocholate on the ex vivo transport of sotalol and flecainide across porcine buccal mucosa were studied. The permeated amounts at 3 h (Q) and fluxes (J) of sotalol in an aqueous solution at pH 7.4 and 9.0 were similar. At pH 7.4, in contrast to pH 9.0, the addition of 1.0% (w/v) sodium glycocholate decreased Q and J four and five fold. Flecainide base in propylene glycol resulted in a nine and 12 fold higher Q and J as compared with an aqueous solution of flecainide acetate at pH 5.8. The presence of sodium glycocholate reduced the transport rate of the flecainide base. However, Q and J were increased 110 and 75 fold by adding 1.0% (w/v) sodium glycocholate to a solution of flecainide acetate at pH 5.8. Sodium glycocholate seems to be an effective penetration enhancer for the buccal absorption of the more polar ionized form of flecainide in an aqueous solution. Sodium glycocholate does not seem to improve the transport of sotalol.

Psychiatrists' views of managed care and the future of psychiatry

Managed care aims to insure the health of a population rather than that of an individual. This paper compiles opinions of psychiatrists and others on managed care and lists ways managed care potentially affects psychiatry. Managed care reverses the economic incentives indemnity insurance gave doctors to prolong treatment. It encourages psychiatrists to spend less time on empathic discussion and to use more standardized, less costly treatments. Many psychiatrists feel distressed about how managed care has changed their practices. Capitation care will change it further. Current trends suggest the U. S. will use and train fewer psychiatrists. Psychiatrists will spend less time with individual patients and more time planning and guiding the treatment of severely impaired patients. Many more psychiatrists will likely have unprecedented changes imposed on their careers.

Absorption kinetics of oral sotalol combined with cisapride and sublingual sotalol in healthy subjects

AIMS

To study the absorption kinetics of sotalol following administration of different formulations. A formulation which results in fast absorption might be useful in the episodic treatment of paroxysmal supraventricular tachycardia (SVT), atrial fibrillation (Afib) or atrial flutter (Afl).

METHODS

In an open randomized crossover study seven healthy male volunteers were given an intravenous infusion of 20 mg sotalol, for assessing the absolute bioavailability, an oral solution containing 80 mg sotalol, an oral solution containing both 80 mg sotalol and 20 mg cisapride and an 80 mg sotalol tablet, which was taken sublingually.

RESULTS

The addition of cisapride decreased the time at which maximum serum concentrations were reached (tmax) from 2.79 (1.85-4.34) h to 1.16 (0.68-2.30) h (P=0.009) [95% CI: -2.59, -0.55] and increased the absorption rate constant (ka) from 0.49 (0.31-0.69) h(-1) to 1.26 (0.52-5.61) h(-1) (P=0.017). The absolute bioavailability of sotalol was reduced by cisapride from 1.00+/-0.15 to 0.70+/-0.26 (P=0.006), while maximum serum concentrations of both oral solutions were not significantly different. Compared with the sublingually administered tablet with a median tmax of 2.12 (0.89-3.28) h, the sotalol/cisapride oral solution gave a smaller tmax (p=0.009) [95% CI: -1.64, -0.36]. The ka of the sotalol/cisapride solution was significantly (P=0.010) larger than the ka of 0.56 (0.33-0.75) h(-1) found after sublingual administration of the tablet.

CONCLUSIONS

The sotalol/cisapride oral solution might be suitable for the episodic treatment of SVT, Afib or Afl.

Gaps in cardiovascular medication taking: the tip of the iceberg

OBJECTIVE

To search for major gaps in medication-taking behavior predisposing patients to cardiovascular morbidity and mortality.

DESIGN

Convenience sample; cohort prospectively followed for < or = 5 months.

SETTING

General internal medicine and cardiology clinics in a university medical center.

PATIENTS

From among 893 patients, the authors identified 132 eligible individuals and entered 33 subjects (25%) with chronic cardiovascular conditions, 1-3 chronic oral medications for these conditions, overall regimen of < or = 6 drugs, regular visits at 1-3-month intervals, literacy in English, willingness to use electronic monitors, and physician permission to participate.

OUTCOME MEASURES

Medication compliance rates and patterns by patient self-report, physician estimates, pill count, and electronic monitoring of pill vial opening.

RESULTS

Despite moderately complex regimens (5.4 +/- 0.5 pills daily; range 1-11), most subjects took most medications according to the prescription: median intervals between pill vial openings were 1.00, 0.50, and 0.43 days for once, twice, and three times daily dosing, respectively. Medication-taking gaps of > or = 2 times the prescribed interdosing interval occurred for 48% of the patients. Patients' dosing patterns often produced "uncovered" intervals (mean duration 3.7 days, range 0-25) with doubtful pharmacologic effectiveness. These lapses were underestimated by patients and poorly perceived by their treating physicians, despite familiarity with their care. Baseline sociodemographic, psychosocial, medical system, or clinical characteristics did not predict the patterns or degrees of medication noncompliance.

CONCLUSIONS

Major treatment gaps occur frequently, even in carefully selected ambulatory populations, and generally escape detection. The compliance patterns and gaps may contribute to reported excesses of cardiovascular morbidity and mortality.

Determination of replacement and suppressive doses of thyroxine

Suppression daily doses of thyroxine (T4) were determined and the daily amounts of T4 required to replace T4 were established in 217 hypothyroid patients. Patients with Hashimoto's thyroiditis treated daily with 2-3 micrograms/kg lean body mass or 1-2 micrograms/kg body weight T4 had normal serum thyrotrophin (TSH) concentrations, normal response to TSH-releasing hormone (TRH) and normal systolic time intervals but doses higher than 3 micrograms/kg lean body mass or 2 micrograms/kg body weight decreased serum TSH concentrations, with no response to TRH and systolic time intervals typical of hyperthyroidism. In 13/32 (41%) hypothyroid patients with Graves' disease following 131I and/or surgery, the daily T4 replacement dose was similar to that in Hashimoto's thyroiditis patients but in 12 (38%) patients daily doses of 2-3 micrograms/kg lean body mass or 1-2 micrograms/kg body weight T4 increased serum T4 and suppressed TSH levels, and in six (9%) lower doses were required to control hypothyroidism. The T4 suppression dose for patients with thyroid cancer was more than 3 micrograms/kg lean body mass or 2 micrograms/kg body weight, whereas approximately 30% of non-toxic nodular goitre patients required less than 3 micrograms/kg lean body mass. It is concluded that replacement or suppression doses of T4 should be individually determined and that different criteria should be applied for their calculation depending on the thyroid abnormality.

Measuring drug levels in the office: rationale, possible advantages, and potential problems

New technologies allow plasma levels of several drugs to be measured in the physician's office. Although such assays have the advantage of increased convenience for both physician and patient, they have a number of potential problems as well. Regardless of where plasma assays are performed, the physician must understand the rationale and pitfalls of therapeutic drug monitoring.

Pharmacokinetic implications of lorcainide therapy in patients with normal and depressed cardiac function

The influence of cardiac function as measured by the left ventricular ejection fraction on the pharmacokinetic variables of a new antiarrhythmic drug, lorcainide, was investigated in 20 cardiac patients. Patients were divided into two groups: those with normal (ejection fraction greater than .40) or depressed (ejection fraction less than .40) left ventricular function. The elimination half-life, plasma clearance rates, or volume of distribution of lorcainide were not significantly different in patients with either normal or depressed cardiac function. A decrease in arrhythmia frequency could be correlated to plasma lorcainide concentration in the majority of patients, and it was noted that at least 0.1 mg/L of lorcainide was required for the presence of an antiarrhythmic effect. Three unusual cases are presented to illustrate the importance of measuring plasma drug concentrations and calculating the drug pharmacokinetics and to correlate these to the antiarrhythmic response in order to minimize the risk of plasma drug accumulation and side effects. A review of published data shows a three- to sixfold interpatient variation in the elimination half-life of lorcainide with practical implications in its use as an antiarrhythmic drug.

The impact of transtelephonic documentation of arrhythmia on morbidity and mortality rate in sudden death survivors

A post hospital follow-up system based on predetermined antiarrhythmic strategies and telephone transmitters used to record ECGs was helpful in managing post hospital course and improved survival in patients with a history of out-of-hospital sudden death. All patients underwent therapy guided by serial electrophysiologic testing. Of the 47 patients, 19 used the telephone transmitter system and 28 did not. During follow-up, residual symptomatic and silent ventricular arrhythmia was documented in 78% of patients using telephone transmitters. Ventricular tachycardia was transmitted in six patients--all survived. During an average 15-month follow-up, 1 of 19 patients using the telephone transmitter system died vs 12 deaths among the 28 patients who did not use the system (p less than 0.005). These results were independent of ejection fraction, presence of congestive heart failure, amiodarone therapy, and the outcome on electrophysiologic therapy. Thus, patients with a history of out-of-hospital sudden death, discharged following electrophysiologic guided therapy, require repeated antiarrhythmic dose titration for side effects or residual ventricular arrhythmia. Prompt diagnosis and treatment of potentially fatal arrhythmia is crucial and feasible, especially with regular ECG checks through telephone transmission.

Comparison of sustained-release quinidines given twice daily to patients with ventricular ectopy

To compare the steady-state kinetic profiles and ectopy-suppression rates of two sustained-release forms of quinidine with those of a conventional quinidine preparation, 18 patients with ventricular ectopy were studied in randomized crossover fashion. The drugs were conventional quinidine sulfate 300 mg q6h, sustained-release quinidine sulfate 600 mg q12h, and sustained-release quinidine gluconate 648 mg q12h. Following baseline electrocardiographic ambulatory monitoring, each drug was given for three days, with repeat ambulatory monitoring and serial plasma drug level determinations performed on the third day. There were no washout periods between treatments. Plasma quinidine levels were assayed by both enzyme multiplied immunoassay technique (EMIT) and quinidine-specific high-performance liquid chromatography (HPLC) methods. Using actual steady-state HPLC values, there were no differences in the area under the plasma concentration-time curve (AUC) among the three treatments; the dose-corrected AUC was greater for quinidine gluconate than for the other two preparations. Using EMIT values, mean plasma quinidine levels from the conventional quinidine sulfate regimen were greater during the last five hours of the 12-hour study interval. A consistently strong inverse relationship between EMIT plasma quinidine levels and hourly ectopy rates was present in only one of eight (13%) responders. Diurnal variation of quinidine kinetics was observed after two days of each treatment; trough values at midnight were slightly lower than trough values at noon. Among patients demonstrating at least 70% suppression of premature ventricular contractions (PVCs), there were no differences in ectopy rates or ectopy-suppression rates among treatments. Dosing sustained-release quinidine sulfate 600 mg or quinidine gluconate 648 mg q12h was clinically acceptable in the small number of responders studied.

BW A256C, a chemically novel class 1 antiarrhythmic agent. A comparison of in vitro and in vivo activity with other class 1 antiarrhythmic agents

BW A256C (5(3)-amino-6-(2,3-dichlorophenyl)-2,3(2,5)-dihydro-3(5)-imino-2 -isopropyl-1,2,4-triazine) is a novel class 1 antiarrhythmic agent designed to combine the features of potency with reduced central nervous system penetration. BW A256C reduced the maximum rate of depolarization of guinea-pig ventricle and dog Purkinje fibres in vitro (EC50, 2.2 X 10(-6) M and 1.8 X 10(-6) M, respectively), being significantly more potent than quinidine, lidocaine, disopyramide and flecainide. BW A256C was also more potent than these agents at inhibiting aconitine-induced arrhythmias in anaesthetized rats; however, unlike these agents, BW A256C was devoid of hypotensive activity at antiarrhythmic doses. In anaesthetized dogs, intravenous administration of BW A256C (0.25-1 mg kg-1) caused a dose-dependent suppression of ventricular arrhythmias that occurred on reperfusion of an occluded coronary artery. In conscious dogs, intravenous infusion (total dose, 1.5 mg kg-1) or oral administration of BW A256C (1.25-5 mg kg-1) caused dose-dependent suppression of the ventricular ectopic activity that occurred following 20-24 h of permanent coronary artery ligation. In the conscious dog, BW A256C was approximately 7 times more potent and was also longer acting than flecainide. Administration of BW A256C was not associated with any evidence of peripheral or CNS toxicity. However, plasma levels 3-4 times greater than the antiarrhythmic levels were associated with a proarrhythmic activity.

Long-term use of psoralens and ultraviolet A for psoriasis: evidence for efficacy and cost savings

A 7.3-year prospective study of 1,380 patients with psoriasis who were treated with oral methoxsalen (8-methoxypsoralen) and ultraviolet A photochemotherapy (PUVA) revealed that patients who continued on PUVA therapy used inpatient hospital treatment less than one fourth as often as those who had discontinued treatment. Patients who continued to use PUVA therapy also had less extensive psoriasis than did other patients in this cohort who discontinued PUVA therapy. These findings demonstrate that PUVA is an effective outpatient therapy for severe psoriasis. The potential toxicity of PUVA treatment, which was the primary reason that one third of the study patients were concerned about their prolonged or continued treatment, must be balanced against the therapy's apparent effectiveness and relatively low cost.