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Biomedical subjects

C S Sweet

Publications and source records attributed to C S Sweet.

At least 19 recordsLinked to original sources
PubMed1998

Three candidate genes and angiotensin-converting enzyme inhibitor-related cough: a pharmacogenetic analysis.

Unexplained, persistent cough limits the use of angiotensin-converting enzyme (ACE) inhibitors in a significant number of patients. It has been speculated that occurrence of this adverse effect is genetically predetermined; in particular, variants of the genes encoding ACE, chymase, and B2-bradykinin receptor have been implicated. To investigate this question, we determined genotypes for common polymorphisms for these three genes in subjects with a history of ACE inhibitor-related cough. Specificity of the adverse effect was confirmed by a blinded, double-crossover design protocol in which subjects were rechallenged with either lisinopril or placebo. In 99 case subjects and 70 control subjects (who failed to develop cough on rechallenge with ACE inhibitor) thus selected, frequencies for the ACE D and I alleles were 0.56 and 0.44 (cases) and 0.56 and 0.44 (controls), respectively; frequencies for chymase A and B alleles (absence/presence of BstXI site) were 0.56 and 0.44 (cases) and 0.46 and 0.54 (controls), respectively; frequencies for B2-bradykinin receptor + and - alleles (presence/absence of a 21 to 29 nonanucleotide sequence) were 0.52 and 0.48 (cases) and 0.53 and 0.47 (controls), respectively. All observed genotype frequencies were in Hardy-Weinberg equilibrium. There was no evidence for association between genotype at either gene examined and cough (adjusted for gender and age). Our data indicate that common genetic variants of ACE, chymase, and B2-bradykinin receptor do not explain the occurrence of ACE inhibitor-related cough.

Angiotensin-Converting Enzyme Inhibitors↗
PubMed1997

Comparative antihypertensive effects of losartan 50 mg and losartan 50 mg titrated to 100 mg in patients with essential hypertension.

The antihypertensive activity of losartan potassium (losartan, Cozaar), an angiotensin II receptor antagonist, was evaluated in a parallel 12-week, double-blind, placebo-controlled trial in hypertensive patients with mild-to-moderate hypertension. After a 4-week, single-blind, placebo lead-in period, which included monitoring of baseline variables, 366 patients with a group mean sitting diastolic blood pressure of 101 +/- 5 (s.d.) mmHg were assigned randomly to one of three treatment groups: placebo, losartan 50 mg, or losartan 50 mg with the option to titrate to 100 mg after the first 6 weeks if the target sitting diastolic blood pressure (< 90 mmHg) was not reached. To assess the potential blood pressure response associated with the act of titration, patients in the placebo and losartan 50 mg treatment groups with a sitting diastolic blood pressure of > or = 90 mmHg at week 6 were mock titrated (changed to a new tablet containing the same study medication and dose). Sitting diastolic blood pressure was also evaluated at the end of the trial during a 1-week off-drug period to assess for rebound hypertension. At week 6, patients in the active-drug-treatment arms experienced significantly greater peak (6 h post-dose) and trough (24 h post-dose) reduction in systolic and diastolic sitting blood pressures compared with placebo (p < or = 0.01). Based on trough blood pressures at week 12, active drug (both arms) was more effective than placebo in lowering sitting diastolic blood pressure, with a very small additional benefit associated with increasing the dose of losartan to 100 mg in patients who did not reach the target blood pressure after the first 6 weeks on losartan 50 mg. There was no evidence of rebound hypertension during 1 week after withdrawal of losartan. The correlation between baseline plasma renin activity and reduction in peak and trough blood pressure at week 12, although statistically significant, was generally poor in the active treatment groups. In this trial, losartan was efficacious and well tolerated, and was similar to placebo with regard to adverse-experience profile. Adverse experiences that could reasonably be related to excessive lowering of blood pressure were not common and there was no evidence of rebound hypertension.

Antihypertensive Agents↗
PubMed1996

Losartan and low-dose hydrochlorothiazide in patients with essential hypertension. A double-blind, placebo-controlled trial of concomitant administration compared with individual components.

BACKGROUND: Angiotensin II acts at the cellular level through specific angiotensin II subtype I, AT-1 receptors. Losartan is the first of a new class of antihypertensive agents that specifically block angiotensin II at AT-1 receptors. By acting on complementary and different pharmacologic mechanisms, the concomitant use of low doses of hydrochlorothiazide with losartan may offer an additive antihypertensive activity with fewer adverse experiences. METHODS: This double-blind study evaluated losartan concomitantly administered with hydrochlorothiazide as initial therapy in 703 patients with essential hypertension. RESULTS: The greatest reduction in blood pressure was observed in the 50 mg of losartan potassium and 12.5 mg of hydrochlorothiazide group (17.2 mm Hg in sitting systolic blood pressure and 13.2 mm Hg in sitting diastolic blood pressure [P < or = .001]), and the effects of the two components appeared to be additive. Seventy-eight percent of the patients treated with 50 mg of losartan potassium and 12.5 mg of hydrochlorothiazide had an excellent or good antihypertensive response (sitting diastolic blood pressure < 90 mm Hg or > or = 90 mm Hg with a reduction of 10 mm Hg or more). Peak (6 hours after dosing) and trough placebo-adjusted ratios for the losartan-hydrochlorothiazide groups ranged from 62% to 85%, indicating that there was a smooth reduction in sitting diastolic blood pressure that was sustained over 24 hours. The most common clinical adverse experiences (> or = 4%) that occurred with an incidence slightly greater than that reported by the placebo-treated patients were headache, asthenia or fatigue, dizziness, sinusitis, and upper respiratory infection. CONCLUSION: The concomitant administration of losartan potassium, 50 mg, with 12.5 mg of hydrochlorothiazide once daily produced an additive reduction in trough sitting systolic and diastolic blood pressure and was well tolerated.

Adult↗
PubMed1996

An inpatient trial of the safety and efficacy of losartan compared with placebo and enalapril in patients with essential hypertension.

The antihypertensive activity and safety of losartan, a specific and selective antagonist of angiotensin II (subtype 1) receptors, was evaluated in 100 inpatients with mild to moderate essential hypertension. After a 2-week, single-blind, out patient placebo lead-in period, the last 2 days of which included inpatient monitoring of baseline blood pressure, the patients were assigned randomly to receive once-daily doses of either placebo; 50, 100, or 150 mg losartan; or 10 mg enalapril. Patients were treated double blind for 5 days, followed by a day for the study of drug withdrawal. Beginning with the first dose, the three doses of losartan and enalapril significantly decreased peak and trough systolic and diastolic blood pressures compared with placebo (p < or = 0.05). The area under the blood pressure curve was analyzed as an assessment of total blood pressure change throughout the day. On day 1, total blood pressure reduction with losartan (50-150 mg) was slightly less than with enalapril. By day 5 of double-blind treatment, the reduction in blood pressure in these groups was similar, suggesting that losartan has a slower onset of action than enalapril. No rebound hypertension was observed after study-drug discontinuation. Losartan was well tolerated in this trial, with an adverse event profile similar to placebo and enalapril.

Adult↗
PubMed1996

Comparative effects of combination drug therapy regimens commencing with either losartan potassium, an angiotensin II receptor antagonist, or enalapril maleate for the treatment of severe hypertension.

OBJECTIVE: To compare the efficacy and safety of a regimen of losartan potassium (losartan) and a regimen of enalapril maleate (enalapril) in a randomized trial of patients with severe hypertension in which the initial treatments were blinded. DESIGN AND METHODS: Seventy-five patients, 23-74 years of age, with sitting diastolic blood pressure of 115-130mmHg, were enrolled in a 12-site multicenter study. The primary efficacy parameters were the change in trough systolic and diastolic blood pressure, as well as response to treatment in terms of categories of hypertensive response. RESULTS: A gradual reduction in mean sitting diastolic blood pressure was observed in all patients treated from week 1 to 12 (10-29mmHg for the losartan regimen and 14-32 mmHg for the enalapril regimen). At week 4, a substantial number of patients remained on monotherapy at either the initial dose or double the dose of losartan (52%) or enalapril (72%). The blood pressure curves for each treatment were parallel over time. The enalapril-based regimen elicited a statistically significantly greater reduction in blood pressure than the losartan-based regimen, although the mean differences in the blood pressure response between the two treatment groups was small. Based on sitting diastolic blood pressure < 90 mmHg or a reduction in blood pressure of at least 10 mmHg, 98% of the patients assigned to the losartan regimen and 100% of the patients assigned to the enalapril regimen had a satisfactory response with a regimen of one to three antihypertensive drugs. Headache was the most common adverse experience in both treatment groups (occurring in 22% of patients assigned to the losartan regimen and 20% of patients assigned to the enalapril regimen). CONCLUSIONS: In this study, the losartan-based regimen effectively lowered blood pressure, was generally well tolerated, and was generally similar to the enalapril-based regimen in the treatment of patients with severe hypertension.

Adult↗
PubMed1996

Controlled trial of losartan given concomitantly with different doses of hydrochlorothiazide in hypertensive patients.

The purpose of this trial was to evaluate the antihypertensive efficacy of the concomitant administration of selected doses of hydrochlorothiazide (HCTZ) on a background of losartan potassium (losartan) 50 mg, a selective angiotensin II receptor antagonist. Patients with essential hypertension ( > or = 95 mmHg inclusion criteria) with a mean sitting diastolic blood pressure (SiDBP) of 105 +/- 0.4 (S.E.) mmHg entered a 4-week, single-blind monotherapy period of losartan 50 mg once daily. At the end of the monotherapy period, patients whose blood pressure was adequately controlled were discontinued. Patients whose blood pressure was partially controlled based on a SiDBP > 92 mmHg entered a 12 week double-blind period and were randomly assigned to either receive placebo (n = 80), HCTZ 6.25 mg (n = 80), HCTZ 12.5 mg (n = 72) or HCTZ 25 mg (n = 80) in addition to losartan 50 mg. During the losartan monotherapy period, there was a 4 mmHg fall in SiDBP with a further fall of 5 mmHg after 12 weeks of double-blind therapy in the losartan/placebo control group. Based on the between group differences in BP change from the end of the losartan monotherapy period (baseline) to end of 12 weeks of double-blind, the concomitant administration of a very low dose of HCTZ (6.25 mg) with losartan did not significantly decrease SiDBP compared with the fall in blood pressure in the losartan/placebo control group (diff. between groups = -2 (95% C.I.[-4.1, +0.9] mmHg)). However, the concomitant administration of HCTZ 12.5 or 25 mg with losartan 50 mg resulted in significantly different (p < or = 0.05) reductions in diastolic blood pressure compared to the losartan/placebo group (diff. between groups = -4 (95% C.I. [-6.3, -1.1] mmHg) for 12.5mg combination group; -6 (95% C.I. [-8.3, -3.3]) mmHg for the HCTZ 25 mg combination group). The proportions of patients treated with losartan plus HCTZ 12.5 mg or 25 mg that achieved a trough SiDBP < 88 mmHg or a trough SiDBP > or = 88 mmHg but with a decrease of at least 5 mmHg were 71% and 83%, respectively. The percentage of clinical adverse experiences that were considered drug-related as assessed by the investigator were generally similar across all treatment groups. There were no reports of orthostatic hypotension in any of the treatment groups. Changes in serum glucose, potassium and uric acid were not appreciably different amongst the treatment groups. In summary, in patients with predominantly moderate to severe essential hypertension, the addition of HCTZ 12.5 mg or 25 mg to losartan 50 mg produced effective control of blood pressure in a substantial majority of patients who only partially responded to losartan monotherapy. There were no differences amongst the treatment groups with respect to drug-related adverse experiences in this trial.

Adult↗
PubMed1995

Safety and tolerability of losartan potassium, an angiotensin II receptor antagonist, compared with hydrochlorothiazide, atenolol, felodipine ER, and angiotensin-converting enzyme inhibitors for the treatment of systemic hypertension.

This report presents data on the safety and tolerability of losartan potassium (losartan), a selective antagonist of the angiotensin II AT-1 receptor, in approximately 2,900 hypertensive patients treated in double-blind clinical trials. In these studies, headache (14.1%), upper respiratory infection (6.5%), dizziness (14.1%), asthenia/fatigue (3.8%), and cough (3.1%) were the clinical adverse experiences most often reported in patients treated with losartan. These adverse experiences were also frequently reported in patients receiving placebo: 17.2%, 5.6%, 2.4%, 3.9%, and 2.6%, respectively. Dry cough as an adverse event was reported in 8.8% of patients treated with angiotensin-converting enzyme inhibitors, and in 3.1% and 2.6% of patients treated with losartan or placebo, respectively. Only dizziness was considered "drug-related" more often in losartan-treated (2.4%) than placebo-treated (1.3%) patients. In controlled clinical trials, losartan was better tolerated than other antihypertensive agents as determined by the incidence of patients reporting any drug-related adverse experiences. Rates of discontinuation due to clinical adverse experiences in patients who received losartan monotherapy or losartan+hydrochlorothiazide were 2.3% and 2.8%, respectively, compared with placebo (3.7%). No laboratory adverse experiences were unexpected or of clinical importance. First-dose hypotension rarely occurred with losartan or with losartan plus hydrochlorothiazide, and withdrawal effects such as rebound hypertension were not observed in clinical trials. There were no clinically important differences in the clinical or laboratory safety profiles in the demographic subgroups for age, gender, or race. In controlled clinical trials, losartan demonstrated an excellent tolerability profile.

Adult↗
PubMed1995

Efficacy and tolerability of losartan potassium and atenolol in patients with mild to moderate essential hypertension.

The objective of this study was to compare the antihypertensive efficacy and tolerability of losartan potassium (losartan) and atenolol in patients with mild-to-moderate essential hypertension. This was a multinational, prospective, randomized, 12-week double-blind parallel study with a follow-up of 4 to 10 days posttreatment to assess any adverse effects of abrupt therapy withdrawal. Two hundred two patients were randomized (2:1) to treatment with losartan or atenolol, 50 mg once daily. Patients were titrated after 6 weeks to 100 mg once daily if their blood pressure was uncontrolled (sitting diastolic blood pressure > or = 90 mm Hg). Trough sitting diastolic blood pressure reductions at weeks 6 and 12 were similar in both the losartan (-9.2 mm Hg and -8.3 mm Hg) and atenolol (-10.8 mm Hg and -10.1 mm Hg) groups and a similar percentage of patients responded to each drug. Both agents were generally well tolerated, although eight patients (two patients taking losartan, and six taking atenolol) were withdrawn because of clinical adverse events (P < or = .05). Reduction in pulse rate from baseline averaged 10 beats/min in the atenolol group with no pulse rate reduction observed in the losartan group (P < .01). No evidence of rebound hypertension was observed in either group. In conclusion, losartan was as efficacious as atenolol in blood pressure reduction, and was at least as well tolerated.

Adult↗
PubMed1995

Haemodynamic and renal responses to oral losartan potassium during salt depletion or salt repletion in normal human volunteers.

We examined the haemodynamic and renal response to oral losartan potassium (100 mg) during activation of the renin system in humans. Eight healthy volunteers followed a low-salt (40 mmol sodium) diet for 4 days on four occasions 2 weeks apart. Double-blind salt depletion was achieved by 3-day administration of frusemide (40 mg twice daily, b.i.d.) with placebo salt replacement, salt repletion by placebo frusemide (b.i.d.), and active salt replacement (100 mmol/day). On day 4, subjects received randomised double-blind placebo or losartan. Prestudy salt depletion was associated with nonsignificant decreases in serum sodium (138 +/- 2 mM), potassium (3.5 +/- 0.2 mM) and increased urea (6.5 +/- 1.1 mM), and creatinine (91 +/- 6 microM) as compared with screening. Prestudy (day 3) 24-h urinary volume was similar during deplete preparation (placebo 1.707 +/- 0.81 L, losartan 1.509 +/- 0.626 L) or deplete preparation (placebo 1.726 +/- 0.5 L, losartan 1.764 +/- 0.52 L), but sodium excretion was greater during replete preparation. Salt replete supine blood pressure (BP) profiles showed little effect of losartan (mean maximal supine BP -9 +/- 6 mm Hg) as compared with placebo (-1 +/- 4 mm Hg), with a similar relative result for erect BP. After salt depletion, losartan caused a greater response in both supine (-24 +/- 9) and erect (-33 +/- 15) BP than did placebo (supine -12 +/- 5, erect -14 +/- 9). In this protocol after salt depletion, losartan caused a transient increase in urea and creatinine (143 +/- 40 microML) 8 h after dosing as compared with placebo (105 +/- 13 microM).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1995

A randomized, placebo-controlled, double-blind, parallel study of various doses of losartan potassium compared with enalapril maleate in patients with essential hypertension.

The efficacy and safety of various doses of losartan potassium, a specific and selective angiotensin II receptor antagonist, were compared with those of placebo and enalapril maleate 20 mg in patients with mild to moderate essential hypertension in a randomized, double-blind, parallel study. We randomly allocated 576 patients at the end of a 4-week placebo baseline period to 8 weeks of once-daily double-blind treatment with losartan potassium 10, 25, 50, 100, or 150 mg, enalapril maleate 20 mg, or placebo. After 8 weeks of treatment, mean reductions from baseline in supine systolic/diastolic pressure 24 hours after dosing (trough) for losartan potassium 10, 25, 50, 100, and 150 mg, enalapril maleate 20 mg, and placebo were 7.6/7.9, 7.8/6.8, 13.0/10.1, 8.9/9.9, 10.5/9.7, 14.7/11.2, and 3.8/5.6 mm Hg, respectively. Compared with mean changes in supine diastolic pressure in the placebo group, losartan potassium 50 to 150 mg and enalapril maleate 20 mg produced clinically important and statistically significant reductions (P < or = .01) in blood pressure. At 24 hours after dosing, the blood pressure changes obtained with losartan potassium 50 mg were essentially identical to those obtained with enalapril maleate 20 mg. While there was a dose-related effect with losartan potassium from 10 to 50 mg at peak (6 hours after dosing), doses of 10 and 25 mg were not consistently different from placebo 24 hours after dosing. To assess the once-daily effect of losartan potassium, trough-to-peak ratios of the mean changes in supine diastolic pressure after 8 weeks of treatment were calculated.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1995

Effects of losartan on a background of hydrochlorothiazide in patients with hypertension.

The purpose of this multicenter trial was to compare the antihypertensive efficacy and safety of losartan potassium (losartan), a selective angiotensin II receptor antagonist, when added to hydrochlorothiazide in hypertensive patients whose blood pressure was not adequately controlled by 25 mg hydrochlorothiazide monotherapy. After a 4-week monotherapy period of 25 mg hydrochlorothiazide, 304 patients with trough (22 to 26 hours postdose) sitting diastolic pressure between 93 and 120 mm Hg were maintained on 25 mg hydrochlorothiazide and randomized double-blind into treatment arms consisting of either 25, 50, or 100 mg losartan or placebo once daily for 12 weeks. The reductions in sitting diastolic pressure for patients treated with 25, 50, or 100 mg losartan concomitantly administered with 25 mg hydrochlorothiazide were significantly greater (P < or = .05) than the reductions observed in the 25 mg hydrochlorothiazide plus placebo group beginning 1 week after randomization. The antihypertensive response in all groups was greater at week 3 than week 1, with some additional decrease in blood pressure in some groups at later times. Sitting systolic pressures were also significantly reduced in each group over time. Standing blood pressures at week 12 were similar to sitting blood pressures. A dose-response relationship to losartan was observed in this patient population. The percentages of the total drug-related clinical adverse experiences as assessed by the investigator were generally similar in the 25, 50, and 100 mg losartan plus 25 mg hydrochlorothiazide groups (10.3%, 24.4%, and 20.0%, respectively) compared with the placebo plus 25 mg hydrochlorothiazide group (24.7%).(ABSTRACT TRUNCATED AT 250 WORDS)

Angiotensin II↗
PubMed1995

Randomised, double-blind, parallel study of the anti-hypertensive efficacy and safety of losartan potassium compared with felodipine ER in elderly patients with mild to moderate hypertension.

This study investigated the anti-hypertensive efficacy and tolerability of once-daily losartan potassium (50 mg titrated to 100 mg), an angiotensin II receptor antagonist, compared with once daily felodipine extended release (ER) (5 mg titrated to 10 mg), a calcium channel blocker, after 12 weeks of therapy in elderly hypertensive patients. Following a 4-week, single-blind, placebo baseline period, qualifying patients were randomly allocated to 12 weeks of double-blind treatment with losartan potassium or felodipine ER. After 6 weeks, patients with a 24 h post-dose sitting diastolic blood pressure > or = 90 mm Hg had their dose doubled for the remaining 6 weeks. At 6 weeks, there was a greater BP response for felodipine ER than losartan potassium in elderly patients with mild to moderate hypertension. However, after 12 weeks of therapy, losartan potassium reduced BP as effectively as felodipine ER with no differences in mean BP reduction or anti-hypertensive response category between treatment groups. In this study, both treatments were well tolerated; felodipine ER was associated with a numerically higher incidence of headache and oedema while the incidence of asthenia was numerically higher in losartan-treated patients.

Aged↗
PubMed1995

Losartan potassium as initial therapy in patients with severe hypertension.

This 12-week, open-label study was conducted to gain experience with losartan potassium, an angiotensin II receptor antagonist, in patients with severe hypertension. Patients were either untreated or withdrawn from current therapy for at least 48 h before initiation of losartan 50 mg once daily. Patients were titrated to 100 mg as needed to achieve a goal of sitting diastolic blood pressure (SiDBP) 90 or 95 mm Hg. Hydrochlorothiazide (12.5 mg once daily titrated to 25 mg) was added and followed by either a dihydropyridine calcium channel blocker (CCB) and/or atenolol, if BP was not controlled. A total of 179 patients with a pretreatment mean baseline BP of 172 +/- 17/112 +/- 18 mm Hg enrolled in the trial and BP was recorded 24 h after dosing at baseline and weeks 2, 4, 8 and the final week (10-12 weeks). The mean reductions in SiDBP from baseline were 7.3, 9.3, 15.9 and 18.9 mm Hg, respectively, and these changes from baseline were statistically significant, P < 0.001. At the end of the trial, 22% of patients remained on losartan monotherapy, 30% required the addition of hydrochlorothiazide (HCTZ) and 31% required both HCTZ and a CCB; 11% required HCTZ and atenolol while 4% required HCTZ, a CCB and atenolol; 2% of patients were on regimens not specified by the protocol. SiDBP < 90 mm Hg was achieved in 68 patients by the final visit; 24% of these patients were treated with losartan monotherapy (50 or 100 mg), 41% achieved control with the addition of HCTZ (12.5 or 25 mg) and 24% required triple therapy which included losartan, HCTZ and a CCB. As assessed by the investigator, 25% of the patients in the study had drug-related clinical adverse experiences. Headache was the most frequently reported clinical adverse event (26% of patients). No clinically significant changes in laboratory parameters were observed. It is concluded that losartan potassium can be used as initial therapy for patients with severe hypertension and can be administered concurrently with hydrochlorothiazide, calcium channel blockers and atenolol.

Adolescent↗
PubMed1994

Pharmacodynamic activity of intravenous E-3174, an angiotensin II antagonist, in patients with essential hypertension.

Losartan potassium (DuP 753), an orally active angiotensin II receptor antagonist, is metabolized to a more potent active metabolite, E-3174, which contributes to losartan's long duration of action. The acute pharmacodynamic actions of intravenous (i.v.) E-3174 (20 mg infused over 4 h) were compared to placebo (vehicle) in two groups of patients with essential hypertension. Patients with supine diastolic blood pressure (SuDBP) of 100 to 120 mm Hg entered a 2-day inpatient phase and received vehicle on day 1. Patients with SuDBP > or = 95 mm Hg were randomized to double-blind treatment the next day. E-3174 significantly (P < .05) reduced SuDBP compared to placebo, beginning at approximately 100 min after the start of the infusion, with a maximum hypotensive effect at 8 h. Supine systolic blood pressure was also reduced by E-3174. Supine and standing heart rates did not differ between treatments. Mean E-3174 plasma levels were 324.6 ng/mL at 20 min and approximately 1000 ng/mL at the end of the 4-h infusion; during this time there was a modest decrease in blood pressure. Following the infusion, the relationship between plasma E-3174 levels and SuDBP was confounded by much larger decreases in blood pressure, which occurred as plasma drug concentrations declined. Urinary excretions of sodium, potassium, or chloride were not significantly altered by E-3174 nor was the fractional excretion of uric acid significantly different between groups. There were no drug-related or serious adverse experiences and no patient discontinued treatment due to an adverse experience.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1994

Losartan in heart failure: preclinical experiences and initial clinical outcomes.

Losartan potassium (Cozaar) is an angiotensin II receptor antagonist (AT1 selective) which has undergone extensive clinical trials for the treatment of hypertension. This literature survey will review some of the pre-clinical findings with losartan in models of heart failure, and where appropriate, we will compare the haemodynamic findings in animals with similar studies completed in patients. The major conclusion from these trials is that losartan has clear haemodynamic benefits in patients in heart failure and that the drug appears to be well tolerated, with a low incidence of adverse experiences related to impaired renal function.

Angiotensin II↗
PubMed1993

Dose-ranging study of the angiotensin type I receptor antagonist losartan (DuP753/MK954), in salt-deplete normal man.

In a dose-ranging study, the angiotensin type I receptor antagonist losartan (DuP753/MK954) was administered orally to normal volunteers in whom the renin-angiotensin system (RAS) had been activated by a low sodium diet (40 mmol) and frusemide (40 mg twice daily) for 3 days before study. On the fourth day, subjects (n = 12) received placebo and three active doses (5, 10, 25, 50, or 100 mg) in a randomized, double-blind, three-panel, dose-ranging design. On the study day, 24-h urinary sodium excretion was approximately 10-20 mmol Na, with an increase in renin and aldosterone levels at baseline. Dose-dependent decreases in supine and erect blood pressures (BP) were statistically significant for 50 and 100 mg and were associated with a modest increase in supine heart rate (HR) at the higher dose. The peak BP decreases observed suggested that the highest dose studied (100 mg) was not necessarily the maximal response. Active treatments caused no increase in the sodium loss on the study day. Renin was significantly increased by doses > 10 mg in a dose-dependent fashion but there was little change in plasma aldosterone profile. Increase in renin was evident at doses (10 mg) below those significantly affecting overall BP (50 mg). Adverse symptoms were uncommon and limited to postural lightheadedness which was largely dose related. Our results indicate a BP and plasma renin dose-response relation for the orally active angiotensin II (AII) receptor blocker losartan in normotensive subjects with an activated RAS.

Adult↗
PubMed1993

How well have animal studies with losartan predicted responses in humans?

AIM: To compare the biological activity of losartan as seen in several animal studies with results from similar clinical studies in hypertensive patients or normal volunteers. RESULTS: With regard to oral bioavailability and estimates of oral angiotensin II blocking activity, the animal models were reasonably good predictors of the human response. Although formation of the major losartan metabolite E 3174 differs according to species, both animal and human studies suggest an association between plasma drug levels and angiotensin II blockade. The finding that losartan demonstrated increased sensitivity during salt depletion in animals was confirmed in humans. Possible beneficial effects on renal function await further detailed clinical trials. CONCLUSIONS: Losartan has been shown to lower blood pressure in patients with essential hypertension. However, cross-species comparisons are difficult because, unlike humans, animal models of hypertension follow clearly defined hypertensive mechanisms. Differing profiles of E 3174 metabolite formation also make cross-species comparisons difficult.

Angiotensin Receptor Antagonists↗