Pharmacology of converting enzyme inhibitors: new aspects

Continuous recording of vital signs with a wearable device in pediatric patients undergoing chemotherapy for cancer-an operational feasibility study

PURPOSE

Pediatric patients with cancer are at high risk for severe infections. Infections can trigger changes of vital signs long before clinical symptoms arise. Continuous recording may detect such changes earlier than discrete measurements. We aimed to assess the feasibility of continuous recording of vital signs by a wearable device (WD) in pediatric patients undergoing chemotherapy for cancer.

METHODS

In this prospective, observational single-center study, pediatric patients under chemotherapy wore the Everion® WD for 14 days. The predefined patient-specific goal was heart rate recorded in good quality during ≥18/24 h per day, on ≥7 consecutive days. The predefined criterion to claim feasibility was ≥15/20 patients fulfilling this patient-specific goal.

RESULTS

Twenty patients were included (median age, 6 years; range, 2-16). Six patients aged 3-16 years fulfilled the patient-specific goal. Quality of heart rate recording was good during 3992 of 6576 (61%) hours studied and poor during 300 (5%) hours, and no data was recorded during 2284 (35%) hours. Eighteen of 20 participants indicated that this WD is acceptable to measure vital signs in children under chemotherapy.

CONCLUSION

The predefined feasibility criterion was not fulfilled. This was mainly due to important compliance problems and independent of the WD itself. However, continuous recording of vital signs was possible across a very wide age range in pediatric patients undergoing chemotherapy for cancer. We recommend to study feasibility in the Everion® again, plus in further WDs, applying measures to enhance compliance.

TRIAL REGISTRATION

ClinicalTrials.gov (NCT04134429) on October 22, 2019.

Ramipril. A review of its pharmacological properties and therapeutic efficacy in cardiovascular disorders

Ramipril is a long acting angiotensin converting enzyme (ACE) inhibitor, which exhibits similar pharmacodynamic properties to captopril and enalapril. Like enalapril it is a prodrug, which is hydrolysed after absorption to form the active metabolite ramiprilat which has a long elimination half-life, permitting once daily administration. In hypertensive patients daily doses in the range 2.5 to 20 mg are usually effective in reducing high blood pressure and maintaining satisfactory control during long term treatment. Patients who do not respond adequately to monotherapy with ramipril usually respond with the addition of a diuretic such as hydrochlorothiazide or piretanide. Ramipril 5 to 10 mg once daily shows comparable antihypertensive efficacy to usual therapeutic dosages of captopril, enalapril and atenolol in patients with mild to moderate essential hypertension. Preliminary data indicate that ramipril may be effective in indications such as severe essential hypertension and renal hypertension. It has also displayed beneficial effects in patients with moderate to severe congestive heart failure. Ramipril has been well tolerated and exhibits an adverse effect profile typical of ACE inhibitors as a class. In conclusion, ramipril will likely represent a useful alternative ACE inhibitor for use in patients with hypertension or congestive heart failure.

Development of angiotensin II-sensitive OVLT neurons in SHR and WKY rats

Angiotensin II (AII) sensitivity of neurons in the region of the organum vasculosum laminae terminalis (OVLT) was examined electrophysiologically using in vitro hypothalamic brain slices taken from 4-, 9- and 14-week-old spontaneously hypertensive (SHR) and normotensive Wistar-Kyoto (WKY) rats. Micropressure application of AII, its competitive antagonist saralasin, and L-glutamate revealed that neurons in this region of SHR were significantly more sensitive to AII than cells in age-matched WKY preparations. Neuronal sensitivity to L-glutamate was similar between SHR and WKY rats at all ages. Following electrophysiological study, hypothalamic and cortical brain slices were assayed for 125I-labelled AII binding. AII receptor binding in the hypothalamic slices from SHR was elevated significantly above binding in WKY hypothalamic slices at 4, 9, and 14 weeks of age. In contrast, AII binding in cortical slices taken from SHR and WKY rats was similar. These data suggest that altered neuronal AII-sensitivity is not a consequence of hypertension development in SHR and may contribute to its development.

Contribution of renal angiotensin converting enzyme (ACE) to blood pressure regulation: possible role of brush border ACE

The role of renal angiotensin converting enzyme (ACE) in blood pressure regulation is not well understood. In our studies, both acute and chronic treatment of hypertensive rats SHR and SHRSP with ACE inhibitors Enalapril and SA446 had a blood pressure lowering effect that coincided with an inhibition of renal cortical and aortic ACE, but not plasma ACE. Further, ACE activities in the renal cortex and aorta were found to increase with aging of the SHRSP, therefore concomitantly with hypertension development. In the kidney, brush border membranes (BBM) contained abundant ACE. We found that the activities of ACE in the renal cortex closely correlated to the activities in isolated BBM, in Wistar Kyoto rats and in the SHRSP. Thus, renal cortical ACE activity and blood pressure correlated in cases of ACE inhibition and hypertension development. Since the ACE activity in the renal cortex appeared to reflect the enzyme activity in BBM, the brush border ACE may have to be taken into account, in view of the relationship between renal ACE and blood pressure.

Tissue converting enzyme inhibition and cardiovascular effects of converting enzyme inhibitors

Local renin-angiotensin systems have been described in organ controlling cardiovascular function. Following oral administration of converting enzyme (CE) inhibitors the enzyme was inhibited not only in lung vascular endothelium and blood, but also in the heart, kidney, vascular wall, brain and other organs. Evidence for a contribution of tissue CE inhibition to the cardiovascular actions of CE inhibitors is provided by the antihypertensive effect of brain CE inhibition in spontaneously hypertensive rats, by the concomitant persistence of blood pressure decrease and CE inhibition in vascular wall and kidney after chronic oral CE inhibitor treatment, and by the marked effects of oral CE inhibitor pretreatment on cardiac function in isolated rat hearts. Local inhibition of tissue renin-angiotensin systems may therefore be an important factor involved in the beneficial effects of CE inhibitors in cardiovascular diseases such as arterial hypertension, congestive heart failure, and cardiac arrhythmias.

Enalapril. A review of its pharmacodynamic and pharmacokinetic properties, and therapeutic use in hypertension and congestive heart failure

Enalapril maleate is an orally active angiotensin-converting enzyme inhibitor. It lowers peripheral vascular resistance without causing an increase in heart rate. Enalapril 10 to 40 mg/day administered either once or twice daily is effective in lowering blood pressure in all grades of essential and renovascular hypertension, and shows similar efficacy to usual therapeutic dosages of hydrochlorothiazide, beta-blockers (propranolol, atenolol and metoprolol) and captopril. Most patients achieve adequate blood pressure control on enalapril alone or with hydrochlorothiazide. In patients with severe congestive heart failure resistant to conventional therapy, enalapril improves cardiac performance by a reduction in both preload and afterload, and improves clinical status long term. Enalapril appears to be well tolerated, with few serious adverse effects being reported. It does not induce the bradycardia associated with beta-blockers or the adverse effects of diuretics on some laboratory values. In fact, the hypokalaemic effect of hydrochlorothiazide is attenuated by the addition of enalapril. The incidence of the main (but rare) side effects of hypotension in hypovolaemic patients and reduced renal function in certain patients with renovascular hypertension, which are also seen with captopril, might be reduced by careful dosage titration, discontinuation of diuretics, and monitoring of at-risk patients. Thus, enalapril is a particularly worthwhile addition to the antihypertensive armamentarium, as an alternative for treatment of all grades of essential and renovascular hypertension. It also shows promise in the treatment of congestive heart failure.

Effects of converting enzyme inhibitors: ramipril and enalapril on peptide action and sympathetic neurotransmission in the isolated heart

The role of converting enzyme (CE) in heart function was studied by assessing the inhibition of CE activity in rat heart tissue and in isolated perfused hearts from rat, guinea-pig and rabbit (Langendorff technique). Angiotensin I (ANG I) added to the perfusate reduced coronary flow (FLO) in all species, increased force of contraction (CON) in rats, decreased CON in guinea-pigs and had no effect on CON in rabbits. In contrast, bradykinin (BK) increased FLO in all species, decreased CON in rats, increased CON in guinea-pigs and had no effect on CON in rabbits. The CE inhibitors ramipril (HOE498) 1 mg/kg and enalapril (MK421) 30 mg/kg given orally 1 h prior to killing of the animals inhibited the ANG I effects and potentiated the BK effects but had no effects on the action of ANG II. The same doses of the two CE inhibitors produced up to 24 h inhibition of CE activity measured biochemically in the heart after single oral doses. Electrical sympathetic stimulation of the cardiac nerves (SNS) in isolated rabbit heart resulted in an increase of HR and CON and in an initial decrease and subsequent increase of FLO. The effects of SNS on HR and FLO were significantly reduced following HOE498 (1 mg/kg) pretreatment. The results suggest that local CE is involved in the regulation of peptide effects in the heart, including the ANG II-mediated facilitation of neurotransmission.

Enalapril in essential hypertension

It is now well recognised that the renin-angiotensin system plays a key role in the control of blood pressure not only through circulating angiotensin II but through its interaction with the autonomic and central nervous systems. Angiotensin-converting enzyme (ACE) inhibitors have proved to be effective in lowering blood pressure in different types of hypertension. This study evaluates the antihypertensive effects of enalapril, a new, potent, long acting ACE inhibitor. 50 patients with uncomplicated essential hypertension were included in 4 groups. Group I was used to compare the effects of enalapril and propranolol on blood pressure, renal function, plasma renin activity, aldosterone excretion and plasma lipids in 24 patients after 23 weeks. Group II was used to evaluate long term effects (48 weeks) of these drugs in 13 patients. Group III included 32 patients that received enalapril as monotherapy for 6 to 12 weeks. Group IV was studied to estimate the antihypertensive effect of low doses of hydrochlorothiazide in 18 patients receiving enalapril. The effect on mean blood pressure was similar with enalapril and propranolol (enalapril 117 versus 103 mm Hg and propranolol 115 versus 104 mm Hg); however, the glomerular filtration rate decreased with propranolol (105 versus 87 ml/min; p less than 0.05) and was unaltered with enalapril (102 versus 98 ml/min). Triglycerides rose with propranolol (179 versus 231 mg/dl; p less than 0.05) and did not change with enalapril (157 versus 121 mg/dl). In the long term, antihypertensive effects were similar and no significant side effects were observed. In 14/32 patients blood pressure became normal with enalapril alone. Low doses of hydrochlorothiazide (12.5 to 25 mg) decreased mean blood pressure by 10mm Hg when added to enalapril. The antihypertensive effect of enalapril was similar to that of propranolol; however, the lowering effect on glomerular filtration rate of propranolol did not occur with enalapril. A slight rise in triglycerides occurred only with propranolol. No significant side effects were observed with either propranolol or enalapril. Used as monotherapy, enalapril normalised blood pressure in 44% of cases. Addition of low doses of hydrochlorothiazide significantly increased the antihypertensive effect of enalapril.