Pindolol: a review of its pharmacology, pharmacokinetics, clinical uses, and adverse effects

Indole-containing pharmaceuticals: targets, pharmacological activities, and SAR studies

Indole is a prestigious heterocyclic skeleton widely found in both naturally-occurring and biologically-active compounds. Pharmaceutical agents containing an indole skeleton in their framework possess a wide range of pharmacological properties, including antiviral, antitumor, analgesic, and other therapeutic activities, and many indole-containing drugs have been proven to have excellent pharmacokinetic and pharmacological effects. Over the past few decades, the FDA has approved over 40 indole-containing drugs for the treatment of various clinical conditions, and the development of indole-related drugs has attracted significant attention from medicinal chemists. This review aims to provide an overview of all the approved drugs that contain an indole nucleus, focusing on their targets, pharmacological activities, and SAR studies.

[Pharmacokinetic risk factors of beta-blockers overdose in the elderly: Case report and pharmacology approach]

Beta-blockers are widely prescribed in elderly patients and may induce severe adverse drug reactions. We report a case of bisoprolol-induced bradycardia in an elderly patient with impaired renal function and use of cytochrome P450 inhibitors. A literature review has been performed in order to analyze pharmacokinetic risk factors of beta-blockers overdosing in geriatrics. Various mechanisms can result in decreased elimination of beta-blockers. These mechanisms vary according to the beta-blocker agent and may be combined in some individuals, especially elderly patients. This can lead to unexpected overexposure. Knowledge about drug interactions and pharmacokinetic elimination pathways is important for preventing overexposure and adverse drug reactions when using beta-blockers.

Accelerating response to antidepressant treatment in depression: a review and clinical suggestions

OBJECTIVE

The primary objective of this article is to review the literature regarding the speed of response to antidepressant drugs and potential strategies to accelerate the antidepressant response in new antidepressant-free patients with depression. Based on these data, we try to propose both an effective and safe antidepressant treatment strategy to alleviate depressive symptoms at the earliest opportunity.

DATA SOURCES

Data were identified by searches of Medline (1966 to September 2009) and references from relevant articles and books. Search terms included depression, antidepressant, predictor, response, onset, acceleration, and augmentation. As our focus was on the acute phase treatment of depression, articles relevant to treatment-resistant depression were excluded. Only articles written in English or Japanese were consulted.

DATA SELECTION

Studies, reviews, and books pertaining to the treatment of depression with a special regard to accelerating therapeutic effects were selected.

DATA SYNTHESIS

Most of the available treatment guidelines for major depressive disorders recommend the continuous use of antidepressants for 4 to 8 weeks based on the idea of a delayed onset of response to these drugs. Contrary to this conventional belief, the recent data indicate that antidepressants start to exert their effects within 2 weeks and early non-response could predict a subsequent unfavorable outcome.

CONCLUSIONS

These findings suggest the need of revisiting the timing of an antidepressant switch for early non-responders, whereby switching could be commenced in as early as 2 weeks.

Application of liquid chromatography-tandem mass spectrometry method for the analysis of new nonselective beta-adrenergic blocker 1-(1-H-indol-4-yloxy)-3-{[2-(2-methoxy phenoxy)ethylo]amino}propan-2-ol (2F109) in rat plasma

A sensitive and specific liquid chromatography electrospray ionization-tandem mass spectrometry method for the enantioselective determination of the novel beta-adrenolytic compound, 1-(1-H-indol-4-yloxy)-3-{[2-(2-methoxyphenoxy)ethylo]amino} propan-2-ol, in rat plasma has been developed and validated. Chromatography was performed on a reversed-phase Chiralcel OD-RH analytical column (150x4.6 mm, 5 microm, Daicel Chemical Industries, Tokyo, Japan) with isocratic elution using a mobile phase containing acetonitrile and water with 0.01% formic acid. Detection was achieved by an Applied Biosystems MDS Sciex (Concord, Ontario, Canada) API 2000 triple quadrupole mass spectrometer. Electrospray ionization (ESI) was used for ion production. The limit of detection in the MRM mode was found to be 1.25 ng/ml. The limit of quantification of both enantiomers was 2.5 ng/ml. The precision and accuracy for both intra- and inter-day determination of 2F109 enantiomers ranged from 2.6 to 12% and from 89.1 to 107.1%. This analytical method allowed us to carry out pharmacokinetic studies in rats. Our findings demonstrate that 2F109 shows stereoselective disposition in rat plasma after i.v. administration. The terminal half-lives of (+)-(R)-2F109 and (-)-(S)-2F109 were 33.5 and 42.6 min, respectively. The AUC0-inf of (+)-(R)-2F109 exceeded that of (-)-(S)-2F109.

Open trial of pindolol in the treatment of fibromyalgia

BACKGROUND

Evidence suggests that fibromyalgia is related to both chronic sympathetic hyperactivity and decreased levels of serotonin.

OBJECTIVE

To examine the efficacy of pindolol, a mixed serotonin (5-HT)(1A) presynaptic autoreceptor/beta-adrenergic receptor antagonist, in the treatment of fibromyalgia.

METHODS

An open trial was conducted using 20 female patients who met the American College of Rheumatology criteria for fibromyalgia. Treatment was initiated with pindolol 7.5 mg/day and titrated to a maximum dose of 15 mg/day for a total of 90 days. Primary outcome measures were tender point analysis and the Fibromyalgia Impact Questionnaire (FIQ). Anxiety and depression were measured with the Hamilton Depression and Anxiety Scales and Beck Depression Inventory.

RESULTS

There was significant improvement in primary outcome measures, including Tender Point Count (mean +/- SD, 16.3 +/- 2.2 vs 12.3 +/- 5.0; F = 8.9; p < 0.001), Tender Point Score (24.4 +/- 5.7 vs 17.5 +/- 9.4; F = 7.8; p < 0.001), and FIQ (45.3 +/- 10.8 vs 35.0 +/- 15.0; F = 5.6; p < 0.005). The depression and anxiety scores did not change significantly among women who completed the study, while the impact on cardiovascular parameters was clinically insignificant.

CONCLUSIONS

While the current results are encouraging, further studies are needed to determine whether pindolol might be effective in the treatment of fibromyalgia. Limitations of this study include small group size and lack of placebo control.

Measurement and cardiovascular relevance of partial agonist activity (PAA) involving beta 1- and beta 2-adrenoceptors

In the normal heart the ratio of beta 1/beta 2-receptors in both atria and ventricles is about 75:25; in the failing heart the ratio is about 60:40. Stimulation of either beta 1- or beta 2-receptors results in a positive chronotropic and inotropic response. In the periphery, with the exception of lipolysis, renin release, control of intraocular pressure and intestinal relaxation, beta 2-related activity predominates. The nature of the beta 2-receptor is being unravelled and it has now been cloned. The beta-receptor antagonist is 'anchored' via disulfide bonding. Subsequent events involve the regulatory protein guanine nucleotide which couples the receptor to adenylate cyclase. beta-receptor density may by up- or down-regulated. beta-stimulation down-regulates (uncouples and internalizes or sequestrates) and beta-antagonism up-regulates beta-receptor numbers, but the functional implications of such changes are not always clear. A partial agonist occupies a receptor site and competitively inhibits the full agonist (e.g. noradrenaline). A partial agonist differs from a full agonist in that maximal response of a tissue is less. When background sympathetic activity is absent or very low a partial agonist will act as an agonist, e.g. increase heart rate, but when background tone is high the partial agonist will behave functionally as an antagonist, e.g. decrease heart rate. In animals partial agonist activity (PAA) can be assessed in many ways. In the catecholamine-depleted (reserpine or syrosingopine), vagotomized or pithed, intact animal beta-activity can be assessed via changes in heart rate, cardiac contractility and atrioventricular conduction. Isolated organs can also be used such as atria, papillary muscle, tracheal, mesenteric artery and uterine preparations. The choice of animal is important as marked species differences in response can occur. In man assessing PAA is difficult due to the presence of an intact sympathetic system: the problem can be overcome by autonomic blockade of constrictor and vagal reflexes with prazosin, clonidine and atropine but leaving the beta-receptor mediated responses unimpaired. beta 1- and beta 2-selective PAA can also be gauged via an increased sleeping heart rate (basal sympathetic tone) in the presence and absence of a beta 1- and beta 2-selective antagonist. beta 1-selective PAA can also cause an increase in resting systolic blood pressure, beta 2-selective PAA may be further assessed by a fall in DBP, increased blood flow, fall in peripheral resistance or increased finger tremor.(ABSTRACT TRUNCATED AT 400 WORDS)

Stereoselective renal clearance of pindolol in humans

In this study, pindolol, a beta-adrenoceptor blocking agent marketed as a racemic mixture, was used as a model compound to investigate stereoselective renal clearance of organic cations in human beings. Six normal subjects received an oral dose of 20 mg racemic pindolol. Heart rate and blood pressure were measured throughout the study. A stereospecific high performance liquid chromatographic procedure was used to quantitate the concentrations of d- and l-pindolol in plasma and urine. Renal clearance and other pharmacokinetic parameters of both enantiomers were calculated and compared. The renal clearance of l-pindolol was greater than that of d-pindolol in all subjects. The renal clearance (mean +/- SD) was 240 +/- 55 ml/min for l-pindolol and 200 +/- 51 ml/min for d-pindolol (P less than 0.01). Since stereoselective binding to plasma proteins was not observed, differences in renal clearance between d- and l-pindolol were caused by either stereoselective renal transport, or stereoselective renal metabolism. The area under the plasma concentration-time curve, the amount of drug excreted, and the half-life of l-pindolol were greater than those of d-pindolol, which suggests that pindolol was also eliminated stereoselectively by nonrenal routes. The slopes of the resting heart rate vs. the plasma concentration of l-pindolol were significantly less than zero and were significantly correlated to the pretreatment heart rate, which supports the hypothesis that intrinsic sympathetic tone largely determines the effect of pindolol on the resting heart rate. The observation that pindolol is eliminated stereoselectively by the kidney may have clinical implications for other racemic drugs that are renally eliminated.