Efficacy, end points and eventualities: sumatriptan/naproxen versus butalbital/paracetamol/caffeine in the treatment of migraine.
Lisinopril (LIS) is a lysine analog of enalaprilat, the active metabolite of enalapril, an angiotensin-converting enzyme inhibitor (ACEI). Unlike enalapril, the precursor of enalaprilat, LIS is not a prodrug but has equal ACEI efficacy and potency and a slightly longer duration of action after oral administration. Short-term (12 weeks) and long-term (24 weeks) blood pressure control has been studied with LIS, hydrochlorothiazide (HCTZ), and LIS + HCTZ when given once a day. Drug treatment had three phases: (i) 2-4 weeks of single-blind placebo washout; (ii) 12 weeks of double-blind comparison therapy with LIS 20, 40, and 80 mg vs. HCTZ 12.5, 25, and 50 mg, vs. LIS + HCTZ 20 + 12.5, 40 + 25, and 80 + 50 mg; (iii) 13-24 weeks single-blind LIS vs. LIS + HCTZ. Starting double-blind therapy at the lowest dose, all three groups doubled the dose at weeks 4 and 8 if BP was not controlled with sitting diastolic BP (SDBP) less than 90 mm Hg. At the end of 12 weeks of double-blind therapy, uncontrolled HCTZ-only and LIS-only treatment groups were advanced to combination LIS + HCTZ therapy but uncontrolled LIS + HCTZ patients were dropped. Mean BP reductions (systolic/diastolic, mm Hg) for all three groups after 12 weeks of double-blind comparison therapy were: (i) LIS (n = 162), -16.6/-12.5; (ii) HCTZ (n = 155), -10.4/-6.8; (iii) LIS + HCTZ (n = 74), -23.9/-18.2 with p less than 0.01 for all groups compared to baseline.(ABSTRACT TRUNCATED AT 250 WORDS)
Intracoronary enalaprilat improves coronary microvascular function and protects myocardium from procedure-related injury in patients with coronary artery disease undergoing PCI. Larger studies are warranted to investigate whether these effects of enalaprilat could result into a significant clinical benefit.
The proteolytic degradation of the enkephalin-containing heptapeptide Tyr-Gly-Gly-Phe-Met-Arg-Phe (YGGFMRF) was investigated by incubating the peptide with synaptic membranes from mouse whole brain and characterizing the formed products. The degradation products were derivatized with 4-dimethylaminoazobenzene-4'-isothiocyanate and then analyzed by high pressure liquid chromatography and by amino-terminal analysis. The incubation of YGGFMRF with synaptic membranes yielded YGGFM and RF as the degradation products. The angiotensin-converting enzyme (ACE) inhibitors, MK-422 and captopril, potently inhibited the formation of YGGFM and RF with IC50 values of 8 nM and 95 nM, respectively. The "enkephalinase A" inhibitor, thiorphan, weakly inhibited this dipeptidyl carboxypeptidase activity with an IC50 greater than 1 microM. YGGFMRF, MK-422, captopril, and thiorphan all produced a dose-dependent analgesic response in the mouse hot plate test when administered intracerebroventricularly. However, when subanalgesic doses of inhibitors were co-administered with a subanalgesic dose of YGGFMRF, only the ACE inhibitors, MK-422 and captopril, potentiated the analgesic response of the peptide. These data provide in vitro and in vivo evidence that ACE is the primary enzyme involved in the proteolytic degradation of YGGFMRF in the mouse brain.
We investigated the role of nitric oxide (NO) in the control of myocardial O2 consumption in Fischer 344 rats. In Fischer rats at 4, 14, and 23 mo of age, we examined cardiac function using echocardiography, the regulation of cardiac O2 consumption in vitro, endothelial NO synthase (eNOS) protein levels, and potential mechanisms that regulate superoxide. Aging was associated with a reduced ejection fraction [from 75 +/- 2% at 4 mo to 66 +/- 3% (P < 0.05) at 23 mo] and an increased cardiac diastolic volume [from 0.60 +/- 0.04 to 1.00 +/- 0.10 ml (P < 0.01)] and heart weight (from 0.70 +/- 0.02 to 0.90 +/- 0.02 g). The NO-mediated control of cardiac O2 consumption by bradykinin or enalaprilat was not different between 4 mo (36 +/- 2 or 34 +/- 3%) and 14 mo (29 +/- 1 or 25 +/- 3%) but markedly (P < 0.05) reduced in 23-mo-old Fischer rats (15 +/- 3 or 7 +/- 2%). The response to the NO donor S-nitroso-N-acetyl penicillamine was not different across groups (35%, 35%, and 44%). Interestingly, the eNOS protein level was not different at 4, 14, and 23 mo. The addition of tempol (1 mmol/l) to the tissue bath eliminated the depression in the control of cardiac O2 consumption by bradykinin (25 +/- 3%) or enalaprilat (28 +/- 3%) in 23-mo-old Fischer rats. We next examined the levels of enzymes involved in the production and breakdown of superoxide. The expression of Mn SOD, Cu/Zn SOD, extracellular SOD, and p67phox, however, did not differ between 4- and 23-mo-old rats. Importantly, there was a marked increase in gp91phox, and apocynin restored the defect in NO-dependent control of cardiac O2 consumption at 23 mo to that seen in 4-mo-old rats, identifying the role of NADPH oxidase. Thus increased biological activity of superoxide and not decreases in the enzyme that produces NO are responsible for the altered control of cardiac O2 consumption by NO in 23-mo-old Fischer rats. Increased oxidant stress in aging, by decreasing NO bioavailability, may contribute not only to changes in myocardial function but also to altered regulation of vascular tone and the progression of cardiac or vascular disease.