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Myocardial ischemia/reperfusion injury is a serious problem involved in cardiovascular diseases. There data which indicate that some steroids induce cardioprotective effects on myocardial ischemia-reperfusion injury; however their activity and the molecular mechanism involved on myocardial ischemia-reperfusion injury are very confusing. Therefore, in this study some estrogen derivatives (compound 3 to 7) were synthesized with the objective of evaluating its activity on myocardial ischemia/reperfusion injury using an isolated heart model. Additionally, molecular mechanism involved in the activity exerted by the compounds 3 to 7 on perfusion pressure and coronary resistance was evaluated by measuring left ventricular pressure in absence or presence of following compounds; prazosin, metoprolol, indomethacin and nifedipine. The results showed that 7 reduce infarct size compared with the estrone and other estrogen derivatives (compounds 3, 4, 5, and 6). Other results showed that 7 significantly increase the perfusion pressure and coronary resistance in isolated heart in comparison with estrone, 3, 4, 5, and 6. Finally, other data indicate that 7 increased the left ventricular pressure in a dose-dependent manner; however, this phenomenon was significantly inhibited by nifedipine. In conclusion, all these data suggest that 7 exert a cardioprotective effect through calcium channels activation and consequently induce changes in the left ventricular pressure levels. This phenomenon results in decrease of myocardial necrosis after ischemia and reperfusion.
We evaluated the effects on blood pressure (BP) and biochemical parameters of doxazosin GITS (gastrointestinal therapeutic system) as a third-line antihypertensive agent among 10,069 participants in the Anglo-Scandinavian Cardiac Outcomes Trial--Blood Pressure Lowering Arm (ASCOT-BPLA) whose BP remained above 140/90 mm Hg (130/80 mm Hg in those with diabetes mellitus). Among those who received doxazosin, mean age was 63 years (SD 9 years), 79% were male, and 32% had diabetes. Doxazosin was initiated a median of 8 months (interquartile range 3 to 24 months) after randomization and was added to a mean of 2.0 (SD 0.3) other antihypertensive drugs; the mean starting and final doses were 4.1 (SD 0.6) and 7.0 (SD 3.1) mg, respectively. During a median of 12 months (interquartile range 4 to 31 months) of uninterrupted doxazosin treatment, during which other antihypertensive treatments remained unchanged, mean BP fell 11.7/6.9 mm Hg (SD 18.8/9.6 mm Hg, P<0.0001) from 158.7/89.2 mm Hg (SD 18.3/10.6 mm Hg). After the addition of doxazosin, 29.7% of participants achieved target BP. There was no apparent excess of heart failure among doxazosin users. There were associated modest favorable effects on plasma lipid profiles, but a small rise in fasting plasma glucose was observed. Doxazosin was generally well tolerated, with 7.5% of participants discontinuing the drug because of adverse events, most frequently dizziness, fatigue, headache, and edema.
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In this study we examined the effects of the drugs most commonly utilized in the therapy of overactive detrusor, on the volume-induced contractions of rat urinary bladder. Anticholinergics such as propantheline bromide and emepronium bromide, as well as oxybutynin decreased the amplitude of the voiding contractions after intravenous (i.v.) administration in a dose-dependent way. These anticholinergics, on the other hand, generally increased the frequency of the contractions. Nifedipine dose-dependently reduced the amplitude of the contractions. Flavoxate induced a dose-related decrease in the frequency without effects on the amplitude of the peaks. Its main metabolite 3-methylflavone-8-carboxylic acid (MFCA) was inactive after i.v. administration. Terodiline was active on the amplitude and apparently on the frequency of the voiding contractions. The alpha-adrenoceptor antagonist prazosin, as well as indomethacin, inhibited only the frequency of the voiding contractions. All the drugs active in reducing the frequency of the voiding contractions after i.v. administration, proved effective also after intracerebroventricular (i.c.v.) injection. The model of the volume-induced contractions of rat urinary bladder, seems to be a useful tool to evaluate in vivo the effects of a compound on the bladder, allowing the possibility of distinguishing among antimuscarinics and calcium antagonists, which peripherally decrease bladder contractility, and other drugs inducing a decrease in the frequency of the voiding reflex acting on the micturition centre(s) in the central nervous system (CNS).
The rabbit ear microcirculation was analyzed in a chronic unanesthetized model to evaluate alpha adrenergic microvascular control in a thermoregulatory end organ. This model allowed direct measurement of microcirculatory responses without the effects of anesthetics or inflammatory responses induced by acute surgical intervention. The ipsilateral facial artery was catheterized for drug injections into the experimental ear. Microvascular diameter changes following stimulation or blockade of adrenoceptor (AR) subtypes were observed directly through a chronic microvascular chamber implanted in the rabbit ear. Vascular alpha1- and alpha2-ARs appear to be distributed differently across the arterioles and AVAs of the rabbit ear. Both alpha1- and alpha2-ARs appear to contribute to vasoconstriction of AVAs in the conscious rabbit ear. In contrast, alpha1-AR's (vs alpha2-ARs) appear to predominate in adrenergically mediated sympathetic vasoconstriction of arterioles.
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Nine clinical benign prostatic hyperplasia (BPH) patients were treated with oral terazoin monotherapy (2 mg daily) for 12 weeks. Serum lipid levels (total cholesterol, triglyceride, high density lipoprotein, low density lipoprotein, apoproteins) were estimated prior to and every 4 weeks during treatment in 5 patients. International Prostate Symptom Score (IPSS) and pressure-flow study were evaluated before and 12 weeks after treatment in 4 patients. The total cholesterol level decreased from a baseline of 210 +/- 36.6 mg/dl by 6.6% at the 12th week. This result was not significant but suggested a favorable effect of terazosin on diminishing the risk of coronary heart disease. This effect was marked especially in patients with a total cholesterol level over 200 mg/dl. On the other hand, IPSS improved in all cases. The mean change ranged from 19.5 to 10.0 and the mean peak flow rate from 9.0 to 15.7 ml/s. On Shäffer's nomogram, 1 patient showed improvement of obstruction and the other 3 patients were diagnosed as having week detrusor without obstruction. Clinical BPH patients with hyperlipidemia may markedly benefit from terazosin, which is a safe and useful initial treatment for BPH.
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Eleven (44%) out of 25 patients using doxazosin and 10 (40%) out of 25 patients using terazosin showed improvement in both IPSS and Qmax at the end of the 3rd month and continued using the drug. After 3 months of treatment, increase in Qmax (p < 0.001) and decrease in IPSS (p < 0.01) was significant for both doxazosin and terazosin. Nineteen patients, who did not show improvement in any of the parameters, switched the drug. Of the patients who switched the drug, 2 (4%) showed improvement both in IPSS and in Qmax, while 2 (4%) showed improvement only in IPSS but not in Qmax. The remaining 15 (30%) patients did not show improvement in any of the parameters.
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We previously demonstrated that morphine withdrawal induced hyperactivity of noradrenergic pathways innervating the hypothalamic paraventricular nucleus (PVN) in rats, in parallel with an increase in the neurosecretory activity of the hypothalamus-pituitary-adrenocortical (HPA) axis, as evaluated by corticosterone release. These neuroendocrine effects were dependent on stimulation of alpha-adrenoceptors. In the present study, Fos immunostaining was used as a reflection of neuronal activity and combined with immunostaining for tyrosine hydroxylase (TH) for immunohistochemical identification of active neurones during morphine withdrawal. Dependence on morphine was induced by 7-day chronic subcutaneous implantation of six morphine pellets (75 mg). Morphine withdrawal was precipitated by administration of naloxone (5 mg/kg subcutaneously) on day 8. Fos immunoreactivity in the PVN and also in the nucleus tractus solitarius (NTS)-A2 and ventrolateral medulla (VLM)-A1 cell groups, which project to the PVN, increased during morphine withdrawal. Following withdrawal, Fos immunoreactivity was present in most of the TH-positive neurones of the A2 and A1 neurones. In a second study, the effects of administration of adrenoceptor antagonists on withdrawal-induced Fos expression in the PVN were studied. Pre-treatment with alpha1- or alpha2-adrenoceptor antagonists, prazosin (1 mg/kg intraperitoneally) and yohimbine (1 mg/kg intraperitoneally), respectively, 20 min before naloxone administration to morphine-dependent rats markedly reduced Fos expression in the PVN. Similarly, pre-treatment with the beta antagonist, propranolol (3 mg/kg intraperitoneally), significantly prevented withdrawal-induced Fos expression. Collectively, these results suggest the hypothesis that noradrenergic neurones in the brainstem innervating the PVN are active during morphine withdrawal, and that activation of transcriptional responses mediated by Fos in the HPA axis following withdrawal are dependent upon hypothalamic alpha- and beta-adrenoceptors.
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The number of questionnaires completed was 12,457. Of the completed questionnaires, 70% of the participants reported the use of multivitamins, and 21% reported the use of herbal supplements. Ten percent of all men reported the use of prescription medications for LUTS (AUA-SS greater than 15). Of the men reporting the use of prescription medications, 19% were taking finasteride, 17% doxazosin, 20% terazosin, 23% tamsulosin, and 22% other prescription medications. Moreover, the average AUA-SS was greater for the men taking herbs or supplements than for those who did not take herbs or supplements (P <0.001). Nonetheless, the Sexual Health Inventory for Men score did not show a positive correlation between the intake of alternative medications and the severity of erectile dysfunction.
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Terlipressin reduces portal pressure in cirrhotic patients mainly through intense splanchnic vasoconstriction that decrease portal venous inflow. Hepatic blood flow may also be reduced by terlipressin. Prazosin (an alpha1-adrenoceptor antagonist) has also been proposed to decrease portal pressure in cirrhotic patients possibly through a decrease in the intrahepatic vascular resistance. The current study was aimed to evaluate whether a combination of prazosin and terlipressin exerts more beneficial effects than terlipressin alone.
In rat tail artery, short trains of electrical stimuli evoke both ATP-mediated excitatory junction potentials (EJPs) and a slow noradrenaline (NA)-mediated depolarization (NAD). Here we have investigated the contribution of α(1)- and α(2)-adrenoceptors to the NAD. The α(1)-adrenoceptor antagonist, prazosin (0.1μM), and the α(2)-antagonist, rauwolscine (1μM), reduced the amplitude of the NAD and in combination these agents virtually abolished the NAD. The K(ATP) channel blocker, glibenclamide (10μM) abolished the α(2)-adrenoceptor-mediated component of the NAD, indicating that activation of these receptors produces closure of K(ATP) channels. The α(1)-adrenoceptor-mediated component of the NAD was increased in amplitude by glibenclamide. Changes in membrane conductance were monitored by measuring the time constant of decay of EJPs (τEJP). The τEJP was increased during α(1)-adrenoceptor-mediated depolarization, indicating a decrease in membrane conductance; i.e. closure of K(+) channels. Broad-spectrum K(+) channel blockers (tetraethylammonium, 4-aminopyridine, Ba(2+)) and the TASK-1K(+) channel blocker, anandamide (10μM), did not reduce the α(1)-adrenoceptor-mediated NAD. The α(1)-adrenoceptor-mediated NAD was unaffected by the Cl(-) channel blockers, 9-anthracene carboxylic acid (100μM) and niflumic acid (10μM) or by the non-selective cation channel blocker, SKF 96365 (10μM). These findings indicate that the NAD is produced by activation of both α(1)-and α(2)-adrenoceptors. The α(2)-adrenoceptor-mediated component is produced by closure of K(ATP) channels whereas the α(1)-adrenoceptor-mediated component is most likely mediated by closure of another type of K(+) channel.
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The [3H]-verapamil binding activity of rat cardiac sarcolemmal fragments was studied, using membranes harvested from non-perfused, aerobically-perfused and ischaemic hearts. Glass-fibre filters were found to contain specific, high affinity--(KD 38 +/- 3.1 nM) [3H]-verapamil binding sites--making them unsuitable for use in [3H]-verapamil binding studies. Incubation of membranes from non-perfused hearts in a medium containing 150 mM NaCl, 1 mM CaCl2 and 50 mM Tris revealed two populations of [3H]-verapamil binding sites. When centrifugation instead of filtration was used to separate bound and free [3H]-verapamil, high affinity sites with a KD of 0.57 +/- 0.19 microM and a Bmax of 38 +/- 5.2 pmol mg-1 protein, and low affinity sites with a KD of 78 +/- 27.5 microM and a Bmax of 2.9 +/- 1.3 nmol mg-1 protein were detected. However, only low affinity binding sites could be detected in membranes which had been incubated in a cation-free medium containing 50 mM Tris. [3H]-verapamil binding to the low and high affinity sites was saturable, reversible, stereospecific and displaceable by D600 greater than diltiazem greater than Ca2+ but not by nifedipine, nitrendipine, nisoldipine or prazosin. The two populations of binding sites survived aerobic perfusion and 60 min ischaemia at 37 degrees C. Ischaemia reduced the Bmax and KD but selectivity was maintained.
Serial PSA measurements were performed using the Abbott IMx assay over 1 year in 134 men over the age of 55 years participating in the Hytrin Community Assessment Trial (HYCAT). HYCAT is a 1-year, randomized, placebo-controlled, double-blinded study of the alpha1-adrenergic antagonist terazosin. All men had lower urinary tract symptoms and a clinical diagnosis of BPH with an American Urological Association (AUA) symptom index of 13 points or more, an AUA bother score of 8 points or more, and a peak urinary flow rate of less than 15 mL/s. PSA was measured at baseline and at 8, 26, 39, and 52 (end of study) weeks.
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The attenuation in drug-induced reinstatement is likely not due to prazosin-induced suppression of activity. These results suggest alpha1-adrenergic mechanisms contribute to reinstatement in rats and perhaps, to relapse in addicts.
Chlorpromazine, given either subcutaneously (0.375 mg/kg) or unilaterally into the preoptic/anterior hypothalamic area through a chronically implanted cannula (20 micrograms), was found to enhance the hypothermic response to delta-9-tetrahydrocannabinol (THC; 5 mg/kg i.p.) in unrestrained adult male MF1 mice, kept at 22 degrees C. In mg/kg terms, chlorpromazine was no more potent when injected into the preoptic/anterior hypothalamic area than when given subcutaneously. Phentolamine (54 micrograms) had no significant effect on hypothermia induced by THC when injected into the hypothalamus although it did enhance this response when given subcutaneously (15 mg/kg). Hypothermia induced by THC was also enhanced by flupentixol (0.375 mg/kg s.c.), piflutixol (23.4 micrograms/kg s.c.), pentolinium (5 mg/kg s.c.), prazosin (0.1875 mg/kg s.c.) and indoramin (6 mg/kg s.c.) but not by SCH 23390 (6 mg/kg s.c.) or sulpiride (40 mg/kg s.c.). When taken together with the results from a previous study, these data support the hypothesis that chlorpromazine enhances hypothermia induced in mice by THC by antagonizing alpha-adrenoceptors so as to decrease the capacity of the animals to minimise peripheral blood flow by vasoconstriction. The present data also support the hypothesis that flupentixol and piflutixol interacted with THC not by antagonizing dopamine at D1 or D2 receptors but rather by blocking alpha-adrenoceptors.
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We studied the effects of a 30-day potassium (K+)-deficient diet on blood [K+] myocardial adrenergic receptor densities, serum catecholamines, and epinephrine arrhythmogenicity in adult laboratory rats (250 +/- 25 g). Within 3 days of beginning the K+-deficient diet, blood [K+] decreased by 50%. After 5 days, the myocardial alpha-1 density increased (62 +/- 2 vs 148 +/- 16 fmols/mg protein), and the total beta receptor increased (95 +/- 5 vs 273 +/- 49) without significant change in receptor affinity. However, 18-21 days of this diet was necessary to produce an increase in the duration of epinephrine arrhythmias (from 56 +/- 8 to 224 +/- 21 s). While prazosin block of the alpha-1 receptor in hypokalemic rats caused a significant, 42% reduction in arrhythmic duration and propranolol block caused a 62% reduction, both prazosin and propranolol were necessary to return arrhythmia times to normal (44 +/- 0.3 mmols/dL). Total serum catecholamines were reduced after 3 days of the diet (from 482 +/- 37 to 299 +/- 31 pg/ml) and remained depressed throughout the 30 days of the K+ diet. The results of this study indicate that prolonged restriction causes a reduction in serum catecholamines, an increase in myocardial alpha-1 and beta receptors densities, and an increase in epinephrine arrhythmogenicity. All of these changes were reversed within 5 days of initiating a normal dietary K+ intake.
1. The subtypes of alpha 1-adrenoceptor mediating contractions to exogenous noradrenaline (NA) in rat aorta have been examined in both biochemical and functional studies. 2. Incubation of rat aortic membranes with the irreversible alpha 1B-adrenoceptor antagonist, chloroethylclonidine (CEC: 10 microM) did not change the KD of [3H]-prazosin binding in comparison to untreated membranes, but reduced by 88% the total number of binding sites (Bmax). 3. Contractions of rat aortic strips to NA after CEC (50 microM for 30 min) incubation followed by repetitive washing, showed a marked shift in the potency of NA and a partial reduction in the maximum response. The residual contractions to NA after CEC incubation were not affected by prazosin (10 nM). 4. The competitive antagonists prazosin, terazosin, (R)-YM-12617, phentolamine, 5-methylurapidil and spiperone inhibited contractions to NA with estimated pA2 values of 9.85, 8.54, 9.34, 7.71, 7.64 and 8.41, respectively. 5. The affinity of the same antagonists for the alpha 1A- and alpha 1B- adrenoceptors was evaluated by utilizing membranes from rat hippocampus pretreated with CEC, and rat liver, respectively. 5-Methylurapidil and phentolamine were confirmed as selective for the alpha 1A-adrenoceptors, whereas spiperone was alpha 1B-selective. 6. A significant correlation was found between the pA2 values of the alpha 1-adrenoceptor antagonists tested and their affinity for the alpha 1B-adrenoceptor subtype, but not for the alpha 1A-subtype. 7. In conclusion, these findings indicate that in rat aorta most of the contraction is mediated by alpha 1B-adrenoceptors, and that the potency (pA2) of an antagonist in this tissue should be related to its antagonistic effect on this subtype of the alpha 1-adrenoceptor population.
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We attempt to determine whether terazosin is effective therapy for the treatment of prostatism-like symptoms in women.
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Hypertension is a major cause for hypertrophic remodelling of the myocardium. Agonistic autoantibodies to extracellular loops of the alpha(1)-adrenergic receptor (alpha(1)-AR) have been identified in patients with arterial hypertension. However, intracellular reactions elicited by these agonistic antibodies remain elusive. An anti-peptide antibody (anti-alpha(1)) was generated against the second extracellular loop of the alpha(1)-AR that bound to its peptide epitope with high affinity (K (D) approximately 50 nM). We studied anti-alpha(1) effects on intracellular calcium (Ca(i)), a key factor in cellular remodelling, and receptor-mediated cardiac protein phosphorylation. Anti-alpha(1) induced pronounced but transient increases in Ca(i) in CHO cells expressing the human alpha(1)-AR (CHO-alpha(1)) and in neonatal cardiomyocytes. Preincubation experiments failed to demonstrate a tonic effect of anti-alpha(1) on Ca(i). However, preincubation with the antibody attenuated the effect of the alpha(1)-AR antagonist prazosin. In neonatal cardiomyocytes anti-alpha(1) induced a robust phosphorylation of a 15-kDa protein that is involved in alpha(1)-AR signalling. Our data support the notion that elevation of Ca(i) is a general feature of agonistic antibodies' action and constitute an important pathogenic component of hypertension-associated autoantibodies. Furthermore, we suggest that agonistic antibodies to the alpha(1)-AR contribute to hypertrophic remodelling of cardiac myocytes, and that the cardiac 15-kDa protein is a relevant downstream target of their action.
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Acetone extract prepared from the plasma membranes of human erythrocytes contained substances which induced the contraction of the thoracic aortic strip of rabbit in vitro and caused blood pressure elevation in rat upon intravenous injection. The contractile response was inhibited by the alpha 1-adrenergic antagonist prazosin. By HPLC/electrochemical detection as well as radioenzymatic assay, large amounts of norepinephrine (NE) (14 +/- 4 [SE] ng/ml packed cells) and epinephrine (E) (16 +/- 2 ng/ml packed cells) were found in the extract. Using the same amounts as in the extract, we were able to demonstrate additive effect between NE and E. The possibility that erythrocyte membranes may play a role in the regulation of NE and E in circulation is suggested.
To study the vascular adrenergic response in hypertensive and normotensive female rats, with a focus on the influence of oestrogen.
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In the absence of direct head-to-head comparative trials, the role of alfuzosin ER in the management of symptomatic BPH relative to that of other AARAs is unclear. Because the effect size (drug response minus placebo response) of alfuzosin ER is comparable to that of other AARAs, marked differences in efficacy are unlikely. Extrapolating from direct comparative trials between these agents and alfuzosin IR/SR, alfuzosin ER would be expected to have better cardiovascular tolerability (eg, in terms of dizziness and orthostasis) than prazosin, terazosin, or doxazosin, and to have similar tolerability to tamsulosin. However, the existing data do not suggest that alfuzosin ER is likely to represent a significant advance over tamsulosin.
The mean changes from base line in the symptom scores in the placebo, finasteride, terazosin, and combination-therapy groups at one year were decreases of 2.6, 3.2, 6.1, and 6.2 points, respectively (P<0.001 for the comparisons of both terazosin and combination therapy with finasteride and with placebo). The mean changes at one year in the peak urinary-flow rates were increases of 1.4, 1.6, 2.7, and 3.2 ml per second, respectively (P<0.001 for the comparisons of both terazosin and combination therapy with finasteride and with placebo). Finasteride had no more effect on either measure than placebo. In the placebo group, 1.6 percent of the men discontinued the study because of adverse effects, as did 4.8 to 7.8 percent of the men in the other three groups.
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Population-based case-control study.
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The mean (range) stone size was 4.2 (2-10) mm. Ten patients were admitted directly from the ER and 121 were discharged home. Of the 121 discharged patients, 48 (40%) were prescribed MET. In all, 46 patients received tamsulosin 0.4 mg and two received doxazosin 2 mg; no patient was prescribed steroids. The mean size of passed stones was statistically significantly lower than that of stones that did not pass (P < 0.05). Patients prescribed MET had a 23% chance of needing surgery, vs 32% in those not prescribed MET (P < 0.05). Seventy-one (61%) patients were followed up by a urologist, 27 (23%) by a primary-care physician, and eight (7%) had no further follow-up. Ultimately, 31 (23%) patients had a metabolic evaluation and it was abnormal in 29 (95%).
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The evolution of antihypertensive drug use in the Glasgow Blood Pressure Clinic between 1969 and 1986 was determined, from computerized data, by extracting percentages of new patients prescribed different drugs at their first clinic visit. Prescribing of adrenergic neuron blockers and centrally acting drugs (methyldopa and clonidine) was common in the early years but declined rapidly until, after 1975 and 1980, respectively, it remained at 10% or less. Diuretics, mainly thiazides, were prescribed for 20% of patients in 1969 to a peak of 55% in 1980. beta-Blockers were first used during the early 1970s and their use peaked in 1980, when they were prescribed for over 60% of new patients. They remained a first-choice treatment in more than 40% of patients. Calcium channel blockers were first used in 1980 and by 1986 were prescribed for 15% of new patients. Angiotensin-converting enzyme inhibitors were used from 1982 and in 1986 were prescribed for 7% of new patients. These two classes of drugs are more expensive than older drugs. However, because of their low usage, this did not greatly influence treatment costs up to 1986, as beta-blockers and thiazides remained widely used.