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PubMed1989

Pharmacokinetics and antihypertensive effects of low dose clonidine during chronic therapy.

Using a sensitive and specific radioimmunoassay the pharmacokinetic disposition of clonidine was determined in hypertensive patients after a single dose and then after 5, 28 and 56 days of chronic dosing with 75 micrograms bd. Following a single dose of clonidine maximal plasma concentrations of 0.34 +/- 0.06 ng/ml were achieved after 3.6 +/- 1.2 hours. After 5 days of repetitive dosing the maximal concentration was significantly higher, 0.66 +/- 0.06 ng/ml and remained so throughout chronic therapy (P = 0.018). The AUC, Tmax and T1/2 did not differ significantly between the acute dose and the chronic dosing pharmacokinetic studies. Clonidine also produced a significant fall in blood pressure. Supine diastolic blood pressure fell from 106 +/- 5 mmHg predose to 99 +/- 6 mmHg 2 hours after the first dose (P less than 0.05). The corresponding values after cyclopenthiazide alone were 108 +/- 8 and 105 +/- 8 mmHg (P = 0.13). Similar falls in blood pressure were produced during chronic therapy.

Adult↗
PubMed2001

Estimating the relative stability of polymorphs and hydrates from heats of solution and solubility data.

The transition temperature, T(t), of polymorphs is estimated from both their heats of solution and solubilities (or intrinsic dissolution rates) determined at any one temperature (e.g., ambient). At a given temperature, T, the enthalpy difference, DeltaH, between polymorphs, I and II, is equal to the difference between their heats of solution, whereas the free energy difference, DeltaG, can be estimated by the equation, DeltaG = -RTln (c(I)/c(II)) or DeltaG = -RTln (J(I)/J(II)), where c is the solubility and J is the intrinsic dissolution rate. The entropy difference, DeltaS, is evaluated as (DeltaH - DeltaG)/T. Because the heat capacity difference,DeltaC(p) between polymorphs is small enough to be neglected, the transition temperature may be estimated by the equation, T(t) = DeltaH/DeltaS. The thermodynamic stability relationships of the polymorphs (i.e., whether they are enantiotropes or monotropes) are predicted from the value of T(t) and the melting temperature. The T(t) values for auranofin, carbamazepine, chloramphenicol palmitate, cyclopenthiazide, gepirone hydrochloride, lamivudine, MK571, premafloxacin, sulfamerazine, sulfamethoxazole, sulfathiazole, and urapidil, were calculated from reported values of the heats of solution and solubilities (or dissolution rates). The stability relationships deduced from the calculated values of T(t) are in good agreement with those reported using other methods, such as differential scanning calorimetry and interpretation of melting data.

Anti-Infective Agents↗
PubMed1984

Hormones and electrolytes in premenstrual syndrome.

We studied 10 normal and asymptomatic patients with ovulatory cycles and measured serum sodium, potassium, FSH, LH, prolactin, estradiol, progesterone and cortisol. The findings were compared with the levels in 25 patients with ovulatory cycles with premenstrual symptoms (PMS) lasting for 7-14 days prior to the onset of menstrual flow. We found no significant difference in serum sodium and potassium levels between the asymptomatic (control) group and the PMS group, or between the follicular and luteal phases of the menstrual cycle. We found no difference in hormone levels other than an altered estrogen/progesterone ratio in the second half of the luteal phase in seven out of 12 PMS patients with severe symptoms and a higher level of cortisol in the luteal phase in six out of 12 patients with severe PMS symptoms. However, the level of serum cortisol was still within the normal range. There was no significant alteration in the levels of electrolytes or hormones during treatment with Navidrex K (cyclopenthiazide, diuretic) pyridoxine (Vitamin B-6), dydrogesterone ( Duphaston ) alone, or all the three drugs combined.

Adolescent↗
PubMed1992

Diuretic screening in human urine by gas chromatography-mass spectrometry: use of a macroreticular acrylic copolymer for the efficient removal of the coextracted phase-transfer reagent after derivatization by direct extractive alkylation.

A simple and efficient procedure has been developed for the derivatization of diuretic agents in human urine by direct extractive alkylation and their detection by gas chromatography-mass spectrometry. The procedure is an improvement over previous extractive alkylation methods because of the development of a simple clean-up step using a macroreticular acrylic copolymer (SM-7 resin) to remove the coextracted phase-transfer reagent from the organic phase after derivatization. With 1 ml of sample the method gives detection limits in the range 10-50 ng/ml for acetazolamide, probenecid, dichlorphenamide, hydroflumethiazide, furosemide, chlorthalidone, bumetanide, hydrochlorothiazide, quinethazone, bendroflumethiazide, metolazone and cyclopenthiazide.

Acrylic Resins↗
PubMed1987

Liquid chromatographic screening of diuretics in urine.

We describe a liquid chromatographic screening procedure for the detection, in urine, of twelve of the fifteen potassium-depleting diuretics available in Australia. A 2-ml urine sample was acidified with NaH2PO4 (pH 4.1) and extracted with 4 ml ethyl acetate. The sample was cleaned up further by washing with 5 ml Na2HPO4 (pH 7.5). The ethyl acetate was then evaporated to dryness, the residue reconstituted in 100 microliters mobile phase and 5 microliter were injected onto a Merck LiChrosorb RP-18 (5 microns) column. The ultraviolet absorbance of the eluent was monitored at 271 nm for 10 min. The screen was evaluated by giving each of thirty volunteers the lowest recommended dose of one of the diuretics in the study and obtaining urine samples 4, 8 and 24 h after having taken the dose. Twelve diuretics, chlorothiazide, hydrochlorothiazide, quinethazone, chlorthalidone, methyclothiazide, clopamide, frusemide, metolazone, mefruside, bendrofluazide, cyclopenthiazide and bumetanide, were all detectable up to 24 h after a dose. We therefore conclude that the screen would be reliable for the detection of these diuretics in urine.

Chromatography, High Pressure Liquid↗
PubMed1994

Interaction of benzothiadiazides with human serum albumin studied by dialysis and spectroscopic methods.

The interaction of a series of benzothiadiazides with human serum albumin (HSA) was investigated by equilibrium dialysis (ED) and spectroscopic methods including circular dichroism (CD). The primary binding site of benzothiadiazides was designated site II, the diazepam site on the HSA molecule, as indicated by displacement experiments using different site-selective probes. Tyrosine and lysine amino acid residues were probably involved in the binding site of these compounds to HSA. Both electrostatic and hydrophobic interactions were found to play a role in the binding of these compounds to HSA. Among the compounds tested, chlorothiazide had the highest affinity (K1 = 5.5 x 10(4) M-1, K2 = 5.8 x 10(3) M-1). The primary binding affinity of the compounds for HSA was of the order: chlorothiazide > cyclopenthiazide > polythiazide > ethiazide > trichlormethiazide = methyclothiazde > hydrochlorothiazide. Binding was insensitive to the N-B transition of HSA. The binding site is proposed to consist of a cationic site on the surface of the HSA molecular with a hydrophobic crevice to accommodate the aromatic ring of the compounds. Positions 3 and 7 of the benzothiadiazide molecule is thought to affect the binding affinity to HSA.

Benzothiadiazines↗
PubMed2002

Diuretics in the therapy of hypertension.

Antihypertensive monopharmacotherapy with diuretics renders blood pressure (BP) values under control in a large percentage of patients suffering from essential hypertension, and it reduces cardiovascular morbidity and mortality. Diuretics are effective in adult and elderly hypertensive subjects, independently of their race. Treatments with classic (high) doses of antihypertensive diuretics, such as 25 mg hydrochlorothiazide once daily, raise the activity of the RAA system, decrease plasma potassium and magnesium concentrations, and cause untoward changes in carbohydrate metabolism and in the plasma lipid profile. These changes appear to limit the positive response of cardiovascular prognosis to antihypertensive therapy with classic doses of diuretics. Lower doses of diuretics reduce high BP to the sought extent in many patients, and they do not elicit or cause only mild unfavourable neuroendocrine and metabolic changes. When a low dose of an antihypertensive diuretic substance is used as monopharmacotherapy, it may take 12-14 weeks after the initiation of treatment for BP to attain final stable values. The following low-dose oral formulations of diuretics constitute effective once-daily monopharmacotherapies for mild-to-moderate uncomplicated essential hypertension: bendrofluazide 1.25 mg, chlorthalidone 12.5 and 15 mg, cicletanine 50 mg, cyclopenthiazide 0.125 mg, HCTZ 12.5 mg, and torasemide 2.5 and 5 mg. These formulations are safer than classically used high-dose formulations such as hydrochlorothiazide 25 and 50 mg.

Diuretics↗
PubMed2005

Screening procedure for detection of diuretics and uricosurics and/or their metabolites in human urine using gas chromatography-mass spectrometry after extractive methylation.

A gas chromatography-mass spectrometry (GC-MS)-based screening procedure was developed for the detection of diuretics, uricosurics, and/or their metabolites in human urine after extractive methylation. Phase-transfer catalyst remaining in the organic phase was removed by solid-phase extraction on a diol phase. The compounds were separated by GC and identified by MS in the full-scan mode. The possible presence of the following drugs and/or their metabolites could be indicated using mass chromatography with the given ions: m/z 267, 352, 353, 355, 386, and 392 for thiazide diuretics bemetizide, bendroflumethiazide, butizide, chlorothiazide, cyclopenthiazide, cyclothiazide, hydrochlorothiazide, metolazone, polythiazide, and for canrenoic acid and spironolactone; m/z 77, 81, 181, 261, 270, 295, 406, and 438 for loop diuretics bumetanide, ethacrynic acid, furosemide, piretanide, torasemide, as well as the uricosurics benzbromarone, probenecid, and sulfinpyrazone; m/z 84, 85, 111, 112, 135, 161, 249, 253, 289, and 363 for the other diuretics acetazolamide, carzenide, chlorthalidone, clopamide, diclofenamide, etozoline, indapamide, mefruside, tienilic acid, and xipamide. The identity of positive signals in such mass chromatograms was confirmed by comparison of the peaks underlying full mass spectra with reference spectra. This method allowed the detection of the abovementioned drugs and/or their metabolites in human urine samples, except torasemide. The limits of detection ranged from 0.001 to 5 mg/L in the full-scan mode. Recoveries of selected diuretics and uricosurics, representing the different chemical classes, ranged from 46% to 99% with coefficients of variation of less than 21%. After ingestion of the lowest therapeutic doses, furosemide was detectable in urine samples for 67 hours, hydrochlorothiazide for 48 hours, and spironolactone for 52 hours (via its target analyte canrenone). The procedure described here is part of a systematic toxicological analysis procedure for acidic drugs and poisons.

Diuretics↗
PubMed2005

Drug-induced pancreatitis: an update.

BACKGROUND AND AIMS: Many frequently prescribed drugs are suspected to cause acute pancreatitis (AP). The goal of this paper is to bring to light the often occult but real problem of drug-induced pancreatitis (DIP). METHODS: We searched the National Library of Medicine/Pubmed for reported cases of DIP from 1966 to April 30, 2004. Medications implicated in AP are classified based on the strength of evidence into one of three classes of drugs associated with pancreatitis. We reviewed the top 100 prescription medications in the United States for their association with AP. RESULTS: Class I medications (medications implicated in greater than 20 reported cases of acute pancreatitis with at least one documented case following reexposure): didanosine, asparaginase, azathioprine, valproic acid, pentavalent antimonials, pentamidine, mercaptopurine, mesalamine, estrogen preparations, opiates, tetracycline, cytarabine, steroids, trimethoprim/sulfamethoxazole, sulfasalazine, furosemide, and sulindac. Class II medications (medications implicated in more than 10 cases of acute pancreatitis): rifampin, lamivudine, octreotide, carbamazepine, acetaminophen, phenformin, interferon alfa-2b, enalapril, hydrochlorothiazide, cisplatin, erythromycin, and cyclopenthiazide. Class III medications (all medications reported to be associated with pancreatitis). Of the top 100 most frequently prescribed medications in the United States, 44 have been implicated in AP, 14 of them fall into either Class I or II of medications associated with AP. CONCLUSIONS: Among adverse drug reactions, pancreatitis is often-ignored because of the difficulty in implicating a drug as its cause. The physician should have a high index of suspicion for DIP, especially in specific subpopulations such as geriatric patients who may be on multiple medications, HIV+ patients, cancer patients, and patients receiving immunomodulating agents.

Adolescent↗
PubMed1996

Inhibition of thiazide photohemolysis in vitro by antioxidants and a nitrogen atmosphere.

The diuretics acetazolamide, bemetizide, bendroflumethiazide, benzthiazide, benzylhydrochlorothiazide, bumetanide, butizide, chlorazanile, chlorothiazide, chlortalidone, clopamide, cyclopenthiazide, cyclothiazide, diazoxide, etozoline, furosemide, hydrochlorothiazide, hydroflumethiazide, indapamide, mefruside, metolazone, piretanide, polythiazide, trichlormethiazide, and xipamide were screened in vitro for phototoxic effects by means of a photohemolysis test. In all, 19 out of the 25 test substances revealed phototoxic hemolytic properties after irradiation with either solar stimulating irradiation, UVA and/or visible light. Addition of the antioxidants ascorbic acid, alpha-tocopherole or superoxide dismutase significantly inhibited the phototoxic hemolysis, as well as did investigations carried out in a nitrogen rich atmosphere, findings which indicate the involvement of reactive oxygen species in the phototoxic process.

Antioxidants↗
PubMed1987

A search for a model tissue for studying effects of thiazide diuretics.

A search was made for a model tissue of NaCl absorption which would be sensitive to inhibition by diuretics of the thiazide type. A lack of such a model through the years has hampered the analysis of the cellular mechanism of action of this important class of drugs. Using the short-circuit current technique, the urinary bladders of the toads Bufo spinosus and Bufo marinus, and the frog Rana temporaria were investigated regarding the effects of various thiazides. These bladders have NaCl absorptive properties similar to those of the distal renal tubules, and are claimed to be sensitive to the inhibitory effect of thiazides on sodium transport. The short-circuit current (SCC), which is representative of the sodium transport across the epithelium, was reduced by cyclopenthiazide and polythiazide, but only at high concentrations (above 0.1 mM). To rule out the possibility that this was an unspecific effect, attempts were made to block the effect by the 'thiazide blocker' Ex 4877, but without success. This finding, together with the fact that dose-response curves were difficult to obtain, would indicate that these epithelia are not suitable for the stated purpose. Preliminary studies were also conducted on the urinary bladder of the plaice, Pleuronectes platessa, which has a different system of NaCl absorption that is claimed to be rapidly and reversibly inhibited by thiazides. Polythiazide, added to both sides of the bladder, had no effect on SCC.

Animals↗
PubMed1981

Thiazide diuretics inhibit contractions of isolated smooth muscles.

The interaction between thiazide diuretics and contractile responses produced by 5-hydroxytryptamine, acetylcholine, noradrenaline and angiotensin II, has been examined on isolated rat uterus and guinea pig aorta. Hydrochlorothiazide, polythiazide and cyclopenthiazide inhibited the contraction of isolated tissue induced by the spasmogens. These data demonstrated that the tested diuretics possess antagonistic activity on contractions induced by various spasmogens.

Animals↗
PubMed1981

Once daily beta-blocker in hypertension--oxprenolol slow-release.

In a within-patient comparison of conventional oxprenolol administered twice daily with slow-release oxprenolol administered once daily in the treatment of hypertension, twenty patients previously responsive to beta-blockers took each formulation for 4 weeks, after wash-out periods off beta-blocker of 2 weeks' duration. The order of administration of the two forms was randomized, and sixteen patients continued medication with cyclopenthiazide 0.5 mg daily. Blood pressure levels at the end of the 4-week treatment periods were compared with levels at the end of the preceding 2-week wash-out periods. Both formulations lowered blood pressure and pulse rate significantly. There was no difference in their effects on pulse rate or on blood pressure, whether measured by the doctors using standard sphygmomanometers or by the hypertension sister using a random-zero sphygmomanometer. In four patients who measured their own blood pressures at home each morning (before medications), afternoon and night, mean levels were similar with the two formulations. Both formulations were very well tolerated.

Adult↗
PubMed1985

[Decreased renal excretory capacity of uric acid in rats fed a low sodium diet under consecutive administration of thiazide diuretics].

The effect of consecutive treatments with thiazide diuretics on renal handling of uric acid was investigated with clearance experiments using rats. Two weeks of oral administration of trichlormethiazide (2 mg/kg, twice a day) in rats fed an ordinary diet caused no change in the uric acid excretory capacity. However, a week of oral administration of trichlormethiazide (0.1, 0.5 and 2 mg/kg, twice a day) in rats maintained on a purified diet containing low sodium amounts decreased the fractional excretion of uric acid. At 2 mg/kg, the decrease of inulin clearance developed clearly. Similar treatments with hydrochlorothiazide (10 mg/kg) and cyclopenthiazide (0.5 mg/kg) also decreased the inulin clearance and the fractional excretion of uric acid. Administration of the above diuretics during sodium deprivation resulted in a marked rise of the hematocrit and hypokalemia. Purified diet containing low sodium amounts alone did not change the uric acid excretory capacity as compared to the ordinary diet. Trichlormethiazide treatment and continued sodium deprivation caused marked losses of body weight and food intake and promotions of urine output and water intake. Histologically, hyperplasia of the cells and tubular dilatation at macula densa were slightly developed during sodium deprivation. With these severe changes, dilatation of the proximal tubules with flattened and regenerated epithelium was shown by the trichlormethiazide treatment (0.5 mg/kg). From these results, the characteristics of chronic treatment with thiazide diuretics acting on renal uric acid retention could be understood in the rat under sodium deprivation.

Animals↗
PubMed1987

Nicardipine. A review of its pharmacodynamic and pharmacokinetic properties, and therapeutic efficacy, in the treatment of angina pectoris, hypertension and related cardiovascular disorders.

Nicardipine is an antagonist of calcium influx through the slow channel of the cell membrane and has been shown to be an effective and relatively well-tolerated treatment for stable effort angina and rest angina due to coronary artery spasm, and mild to moderate hypertension. Although its exact mechanism of action in these disease states has not been precisely defined, the potent coronary and peripheral arterial dilator properties of nicardipine, with concomitant improvements in oxygen supply/demand and reductions in systemic vascular resistance, are of major importance. Clinical studies have shown that nicardipine appears to be effective in the treatment of chronic stable exercise-induced angina pectoris and possibly in angina at rest due to coronary artery spasm. In the treatment of stable angina, nicardipine has proved to be equally as effective as nifedipine. However, haemodynamic and clinical studies indicate that nicardipine may have a further advantage of not depressing cardiac conduction or left ventricular function, even in patients with compromised cardiac pumping ability. Nicardipine also appears to be useful as initial monotherapy or in combination with other antihypertensive drugs when used in the treatment of mild to moderate hypertension, and may have some advantages over other vasodilators in this regard in that it may not be as frequently associated with fluid retention or weight gain as other similar drugs. In the treatment of hypertension nicardipine has been shown to be as effective as drugs such as hydrochlorothiazide, cyclopenthiazide, propranolol and verapamil in short term studies although confirmation of its long term usefulness in well-designed clinical trials is still required. Similarly, although the use of nicardipine in other disorders such as congestive heart failure and cerebrovascular disease has provided encouraging preliminary results, more studies are needed to clarify its place in their treatment. Side effects appear to be dose related and more frequent within the first few weeks of therapy. Most of these effects are minor and transient in nature and include headache, flushing and peripheral oedema. Thus, there is no doubt that nicardipine provides a suitable alternative to other drugs available for the treatment of angina and hypertension. However, further well-designed comparative clinical trials are needed to clarify its relative place in the long term management of these disorders.

Angina Pectoris↗
PubMed1980

The relevance of hypertension and oedema in pregnancy.

The triad of severe pre-eclampsia is often described as a combination of hypertension, oedema and proteinuria. Hypertension alone arising in the second half of pregnancy however is not associated with any greater perinatal mortality or low birthweight than normotensive primigravidae and it is probable that this hypertension may be either physiological or a manifestation of essential hypertension or, in some cases, a mild form of pre-eclampsia. Oedema also does not necessarily signify abnormality. High weight gain, fluid retention or oedema is associated with a lower incidence of small babies, but with a higher incidence of pre-eclampsia. Considerable amounts of water retention can occur in normal pregnancy, either measured as an increase during pregnancy, or as a fall after delivery. The diuretics cyclopenthiazide, spironolactone and clopamide given prophylactically to high weight gain primigravidae did not prevent the onset of proteinuric pre-eclampsia, but caused the babies to be lighter in weight than those of controls. Sodium potassium and water content of leucocytes from primigravidae with proteinuric pre-eclampsia is the same as in mild pre-eclampsia and normal pregnancy. Although salt and water retention are common features of pre-eclampsia, they do not cause the condition and are not an essential part of it.

Birth Weight↗
PubMed1992

Comparison of antihypertensive and lipid actions of terazosin and atenolol in essential hypertension.

Terazosin is a selective alpha 1-adrenoceptor antagonist; its actions on the serum lipoprotein profile were compared with those of the cardioselective beta-adrenoceptor antagonist atenolol in 40 patients with mild to moderate hypertension. Atenolol and terazosin were titrated over six weeks until blood pressure control (diastolic blood pressure less than 90 mmHg or greater than 10 mmHg fall in blood pressure) or a maximum dose of atenolol 100 mg or terazosin 10 mg had been achieved. Patients not controlled were then prescribed additional diuretic therapy (cyclopenthiazide 0.5 mg and potassium 1200 mg). At each visit blood pressure and adverse events were recorded; plasma lipids were measured at baseline, six and 12 weeks. During titration there was a linear decrease in systolic (-29 mmHg on atenolol and -24 mmHg on terazosin) and diastolic blood pressure (-17 and -12 mmHg) in both groups without subsequent change over the next six weeks; atenolol reduced heart rate (-11 bpm) without change on terazosin. During the initial six weeks the total cholesterol fell in both groups; however, there were significant between-treatment differences in triglyceride responses with a fall on terazosin and a rise on atenolol. Comparing atenolol and terazosin over the total 12 week study (irrespective of thiazide treatment) increased triglyceride levels and reduced cholesterol ratios and HDL were demonstrated on atenolol, contrasting with reduced triglyceride levels and elevated HDL and cholesterol ratios of terazosin.(ABSTRACT TRUNCATED AT 250 WORDS)

Adrenergic alpha-Antagonists↗
PubMed1986

[Mediator concepts and modulation of renal compensatory adaptation].

In the renal compensatory adaptation after the definition and the description of the fundamental phenomena of the functional compensation as well as of the structural adaptation is reported on mediator concepts and on modulations of the renal adaptation processes. Issuing from the central position of the sodium balance a mediator concept on natriuretic hormones (Auriculin and Endoxin) is developed which is supplemented by the renotropin mediator concept. The authors deal with the modulation of the renal compensatory adaptation (e.g. influences of age diet and so on). The pharmacotherapeutic modulation of the renal compensatory adaptation is discussed with regard to the stimulation of the tubulosecretory transport of foreign substances with para-amino hippuric acid as principal substance (including own investigations with cyclopenthiazide [Benesal].

Adaptation, Physiological↗