Prophylactic oral betamimetics for reducing preterm birth in women with a twin pregnancy

BACKGROUND

Twin pregnancies are associated with a high risk of neonatal mortality and morbidity due to an increased rate of preterm birth. Betamimetics can decrease contraction frequency or delay preterm birth in singleton pregnancies by 24 to 48 hours. The efficacy of oral betamimetics in women with a twin pregnancy is unproven.

OBJECTIVES

To assess the effectiveness of prophylactic oral betamimetics for the prevention of preterm labour and birth for women with twin pregnancies.

SEARCH METHODS

We searched the Cochrane Pregnancy and Childbirth Group Trials Register (21 September 2015), MEDLINE (January 1966 to 31 July 2015), EMBASE (January 1985 to 31 July 2015) and reference lists of retrieved studies.

SELECTION CRITERIA

Randomised controlled trials in twin pregnancies comparing oral betamimetics with placebo or any intervention with the specific aim of preventing preterm birth. Quasi-randomised controlled trials, cluster-randomised trials and cross-over trials were not eligible for inclusion.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed trials for inclusion and risk of bias, extracted data and checked them for accuracy. Two authors assessed the quality of the evidence using the GRADE approach.

MAIN RESULTS

Overall, the quality of evidence is low for the primary outcomes. All of the included trials had small numbers of participants and few events. Preterm birth, the most important primary outcome, had wide confidence intervals crossing the line of no effect.Six trials (374 twin pregnancies) were included, but only five trials (344 twin pregnancies) contributed data. All trials compared oral betamimetics with placebo.Betamimetics reduced the incidence of preterm labour (two trials, 194 twin pregnancies, risk ratio (RR) 0.37; 95% confidence interval (CI) 0.17 to 0.78; low quality evidence). However, betamimetics did not reduce prelabour rupture of membranes (one trial, 144 twin pregnancies, RR 1.42; 95% CI 0.42 to 4.82; low quality evidence), preterm birth less than 37 weeks' gestation (four trials, 276 twin pregnancies, RR 0.85; 95% CI 0.65 to 1.10; low quality evidence), or less than 34 weeks' gestation (one trial, 144 twin pregnancies, RR 0.47; 95% CI 0.15 to 1.50; low quality evidence). Mean neonatal birthweight in the betamimetic group was significantly higher than in the placebo group (three trials, 478 neonates, mean difference 111.22 g; 95% CI 22.21 to 200.24). Nevertheless, there was no evidence of an effect of betamimetics in reduction of low birthweight (two trials, 366 neonates, average RR 1.19; 95% CI 0.77 to 1.85, random-effects), or small-for-gestational age neonates (two trials, 178 neonates, average RR 0.90; 95% CI 0.41 to 1.99, random-effects). Two trials showed that betamimetics significantly reduced the incidence of respiratory distress syndrome (388 neonates, RR 0.30; 95% CI 0.12 to 0.77), but the difference was not significant when the analysis was adjusted to account for the non-independence of twins (194 twins, RR 0.35; 95% CI 0.11 to 1.16). Three trials showed no evidence of an effect of betamimetics in reducing neonatal mortality, either with the unadjusted analysis, assuming twins are completely independent of each other (452 neonates, average RR 0.90; 95% CI 0.15 to 5.37, random-effects), or in the adjusted analysis, assuming non-independence of twins (226 twins, average RR 0.74; 95% CI 0.23 to 2.38, random-effects). A maternal death was reported in one trial without a significant difference between the groups (144 women, RR 2.84; 95% CI 0.12 to 68.57).

AUTHORS' CONCLUSIONS

There is insufficient evidence to support or refute the use of prophylactic oral betamimetics for preventing preterm birth in women with a twin pregnancy.

Prophylactic oral betamimetics for reducing preterm birth in women with a twin pregnancy

BACKGROUND

Twin pregnancies are associated with a high risk of neonatal mortality and morbidity due to an increased rate of preterm birth. Betamimetics can decrease contraction frequency or delay preterm birth in singleton pregnancies by 24 to 48 hours. The efficacy of oral betamimetics in women with a twin pregnancy is unproven.

OBJECTIVES

To assess the effectiveness of prophylactic oral betamimetics for the prevention of preterm labour and birth for women with twin pregnancies.

SEARCH METHODS

We searched the Cochrane Pregnancy and Childbirth Group Trials Register (31 January 2012), the Central Register of Controlled Trials (The Cochrane Library 2012, Issue 2), MEDLINE (January 1966 to 1 February 2012) and EMBASE (January 1985 to 1 February 2012).

SELECTION CRITERIA

Randomised controlled trials in twin pregnancies comparing oral betamimetics with placebo or any intervention with the specific aim of preventing preterm birth. Quasi-randomised controlled trials, cluster-randomised trials and cross-over trials were not included.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed trials for inclusion and trial quality. Two review authors extracted data. Data were checked for accuracy.

MAIN RESULTS

Six trials (374 twin pregnancies) were included, but only five trials (344 twin pregnancies) contributed data. All trials compared oral betamimetics with placebo.Betamimetics reduced the incidence of preterm labour (one trial, 50 twin pregnancies, risk ratio (RR) 0.40; 95% confidence interval (CI) 0.19 to 0.86). However, betamimetics did not reduce preterm birth less than 37 weeks' gestation (four trials, 276 twin pregnancies, RR 0.85; 95% CI 0.65 to 1.10) or less than 34 weeks' gestation (one trial, 144 twin pregnancies, RR 0.47; 95% CI 0.15 to 1.50). Mean neonatal birthweight in the betamimetic group was significantly higher than in the placebo group (three trials, 478 neonates, mean difference 111.22 g; 95% CI 22.2 to 200.2). Nevertheless, there was no evidence of an effect of betamimetics in reduction of low birthweight (two trials, 366 neonates, average RR 1.19; 95% CI 0.77 to 1.85, random-effects) or small-for-gestational age neonates (two trials, 178 neonates, RR 0.92; 95% CI 0.52 to 1.65). Two trials (388 neonates) showed that betamimetics significantly reduced the incidence of respiratory distress syndrome but the difference was not significant when the analysis was adjusted for correlation of babies from twins. Three trials (452 neonates) showed no evidence of an effect of betamimetics in reducing neonatal mortality (RR 0.80; 95% CI 0.35 to 1.82).

AUTHORS' CONCLUSIONS

There is insufficient evidence to support or refute the use of prophylactic oral betamimetics for preventing preterm birth in women with a twin pregnancy.

Isoxsuprine hydrochloride in the horse: a review

Isoxsuprine hydrochloride has been suggested for use in horses for treatment of navicular syndrome and laminitis. The drug has been shown to be a beta-adrenoreceptor antagonist with beta-adrenoreceptor agonistic properties, with both characteristics contributing to vasodilation and uterine relaxation. In addition, the drug is capable of decreasing blood viscosity and platelet aggregation. Studies have shown i.v. isoxsuprine to have a plasma half-life of <3 h with a large apparent volume of distribution. Cardiovascular effects resolve rapidly following i.v. administration, but are absent with oral dosing. Oral bioavailability is 2.2% with a high first pass effect. Isoxsuprine has an apparent affinity for melanin that may contribute to extended renal excretion. Clinical trials appear to support the use of isoxsuprine for treatment of navicular disease. However, poor bioavailability, lack of cardiovascular effects following oral administration, superficial support in clinical trials, and new evidence regarding the pathogenesis of navicular syndrome indicate that the use of isoxsuprine for treatment of navicular syndrome or laminitis is questionable at best.

Therapeutic effects of high-dose isoxsuprine in the management of mixed-type impotence

OBJECTIVES

To determine the effectiveness and safety of high-dose isoxsuprine for the treatment of mixed-type erectile dysfunction.

METHODS

Forty-four patients who had vasculogenic impotence diagnosed on the basis of their sexual history, physical examination, laboratory analysis, polysomnographic recording of nocturnal erections, and dynamic color Doppler sonography of the cavernosal arteries were entered into a randomized, double-blind, placebo-controlled, crossover comparison of a placebo with high-dose isoxsuprine hydrochloride (60 mg/day orally). The treatment consisted of two 30-day courses. After a 14-day washout period, the patients who initially received the placebo for 30 days switched to isoxsuprine hydrochloride for 30 days and vice versa. Erectile function, ejaculation, interest in sex, and physical examination findings were investigated before treatment and at the end of each drug period.

RESULTS

Thirty-six patients (82%) completed the entire treatment schedule. Positive clinical results (complete and partial responses) were obtained in 6 men (16.6%) at the end of the isoxsuprine phase and in 7 men (19.4%) after the placebo period. The statistical analysis disclosed no significant difference when isoxsuprine was compared with placebo (P >0.05). Significant drug-related adverse effects occurred in the isoxsuprine group and treatment was discontinued in 2 patients.

CONCLUSIONS

Isoxsuprine is no better than placebo as a first-line treatment for mixed-type erectile dysfunction.

Direct MS-MS identification of isoxsuprine-glucuronide in post-administration equine urine

Isoxsuprine is routinely recovered from enzymatically-hydrolyzed, post-administration urine samples as parent isoxsuprine in equine forensic science. However, the specific identity of the material in horse urine from which isoxsuprine is recovered has never been established, although it has long been assumed to be a glucuronide conjugate (or conjugates) of isoxsuprine. Using ESI/MS/MS positive mode as an analytical tool, urine samples collected 4-8 h after isoxsuprine administration yielded a major peak at m/z 554 that was absent from control samples and resisted fragmentation to daughter ions. Titration of this material with increasing concentrations of sodium acetate yielded m/z peaks consistent with the presence of monosodium and disodium isoxsuprine-glucuronide complexes, suggesting that the starting material was a dipotassium-isoxsuprine-glucuronide complex. Electrospray ionization mass spectrometry negative mode disclosed the presence of a m/z 476 peak that declined following enzymatic hydrolysis and resulted in the concomitant appearance of peaks at m/z 300 and 175. The resulting peaks were consistent with the presence of isoxsuprine (m/z 300) and a glucuronic acid residue (m/z 175). Examination of the daughter ion spectrum of this putative isoxsuprine-glucuronide m/z 476 peak showed overlap of many peaks with those of similar spectra of authentic morphine-3- and morphine-6-glucuronides, suggesting they were derived from glucuronic acid conjugation. These data suggest that isoxsuprine occurs in post-administration urine samples as an isoxsuprine-glucuronide conjugate and also, under some circumstances, as an isoxsuprine-glucuronide-dipotassium complex.

Affinity of isoxsuprine for adrenoreceptors in equine digital artery and implications for vasodilatory action

We used isolated equine digital arteries to study the vasodilatory mechanism of isoxsuprine, and fowl caecum preparations to investigate the affinity of the drug for beta-adrenoceptors. Isoxsuprine is a potent vasodilator of arterial smooth muscle that has been precontracted by an alpha-adrenoceptor agonist such as noradrenaline (log EC50 = -6.33 [-5.98; -6.68]). The present study indicates that its effect is due to alpha-adrenoceptor blockade since: (1) after a long lasting exposure to cumulative doses of isoxsuprine the vasoconstricting action of noradrenaline cannot be restored; (2) isoxsuprine does not promote relaxation on preparations precontracted by PGF2alpha; (3) isoxsuprine shifts the dose-response curve of noradrenaline to the right; and (4) its affinity (pK(B) = 6.90 [6.60; 7.20]) in this experiment is comparable to that in noradrenaline-precontracted preparations and is 14 times lower than that of the selective alpha1-adrenergic antagonist prazosin [pK(B) = 8.04 (7.40; 8.68]). The affinity of isoxsuprine for beta-adrenoceptors was 100 times lower than that of isoprenaline when tested on fowl caecum. This preparation has a large beta-adrenoceptor and negligible alpha-adrenoceptor population concerned with the control of smooth muscle motility. Our data suggest that the alpha-mediated effect of isoxsuprine on horse arterial smooth muscle is due to higher affinity of the drug for alpha- than beta-adrenoceptors rather than low concentration or functionality of beta-sites at this site. According to these data, pure beta2-agonists seem to be more profitable tools to determine vasodilation of the arterial bed in horses legs.

The effect of oral isoxsuprine and pentoxifylline on digital and laminar blood flow in healthy horses

OBJECTIVE

To quantitate blood flow in the palmar digital artery and dorsal laminae of the hoof in standing, unmedicated, nonsedated horses, and in horses treated with oral isoxsuprine, oral pentoxifylline, and intravenous acetylpromazine as a positive control.

STUDY DESIGN

Experimental study; treatments administered in a random cross-over design.

ANIMALS

A total of 6 healthy horses selected with at least one nonpigmented forelimb hoof wall and determined to be free of laminitis.

METHODS

All horses were instrumented with a flow probe placed around one palmar digital artery under general anesthesia and a laser doppler flow probe placed within a hole in the dorsal hoof wall to measure digital blood flow and laminar perfusion respectively. Baseline readings of palmar digital blood flow and laminar perfusion were recorded before and between treatments. Horses were randomly assigned to one of two groups and treated with either isoxsuprine (1.2 mg/kg, orally twice daily for 10 days) or pentoxifylline (4.4 mg/kg, orally every 8 hours for 10 days) in a random cross-over design. Digital blood flow (DBF) and laminar perfusion (LP) were measured on days 2, 5, 7, and 10 of treatment. Horses also received acetylpromazine as a positive control (0.066 mg/kg, intravenously) during the washout period, and measurements were taken every 15 minutes until measurements returned to baseline readings. Data were analyzed by using repeated measures ANOVA.

RESULTS

Digital blood flow (11.2 to 97.7 mL/min) and laminar perfusion (1.0 to 11.1 Capillary Perfusion Units) differed between horses. No statistically significant increases in DBF or LP were detected over the 10 day treatment period with either isoxsuprine or pentoxifylline. Acepromazine resulted in a significant increase (P = .0007) in DBF for approximately 75 minutes beginning 15 minutes after treatment. A mild but insignificant increase in LP was identified after acetylpromazine treatment.

CONCLUSION

Neither isoxsuprine nor pentoxifylline increased blood flow to the digit or dorsal laminae in healthy horses. Acepromazine caused an increased blood flow to the digit. Based on the results of this study acetylpromazine potentially would have a greater effect on improving digital blood flow than oral isoxsuprine or pentoxifylline when treating ischemic conditions of the foot in horses.

Absence of detectable pharmacological effects after oral administration of isoxsuprine

Isoxsuprine is reported to be a peripheral vasodilator used in human and veterinary medicine to treat ischaemic vascular disease. In horses, it is generally administered orally to treat navicular disease and other lower limb problems. To define the scope and duration of its pharmacological responses after oral administration, 6 horses were dosed with isoxsuprine HCl (1.2 mg/kg bwt) q. 12 h for 8 days and then tested to assess the duration and extent of pharmacological actions. There was no significant difference between isoxsuprine and control treatment values for heart rate, spontaneous activity, sweat production, anal muscle tone, core and skin temperatures, and cutaneous blood flow. The lack of pharmacological effect following oral administration was in sharp contrast to the marked response following i.v. dosing reported in earlier experiments.

[Isoxsuprine in hypertension during pregnancy]

The objective of this paper is to demonstrate that isoxsuprine is an effective, quick hypotensive of easy management in the hypertension of pregnancy that does not have adverse effects on the mother-fetus binomial. This study was carried out at the Obstetric Intensive Care Unit at the Gyneco-Obstretrics Hospital in the Centro Médico Nacional La Raza of the IMSS. Fifty patients were chosen and managed according to the protocol management of the hospital; they had a diagnosis of severe toxemia or preeclampsia in patients with 24 weeks or more of pregnancy, with hypertension, edema, convulsions and/or coma state or without concomitant or previous pathological states. All of the patients received isoxsuprine (50 mg in 250 ml of DW5%). We evaluated the hypotensive effect of isoxsuprine according to the time and average dose administered, and its effect on the mother and fetus heart frequency according to the basal values. We valued the APGAR score at minute one and minute five, seconds after the delivery. We analyzed according to the degrees of toxemia and at the end of the obstetric event. We demonstrated a significant decrease in the arterial tension after administration fifteen minutes later with a dose of nine drops (0.29 mcg/min) average and demonstrated at the same time that there are no adverse effects on the mother fetus binomial. Isoxsuprine is an affective, quick and economical hypotensive of easy management that has no adverse effects on mother-fetus glycemia, obstetric bleeding and APGAR score.

Character and duration of pharmacological effects of intravenous isoxsuprine

Isoxsuprine is a therapeutic medication used to treat navicular disease and other lower limb problems in horses and is one of the more frequently detected therapeutic agents in racing horses. In a crossover study, horses were administered isoxsuprine i.v. to determine the character and duration of its pharmacological effects. Isoxsuprine significantly increased heart rate 5-150 min following injection. Unrestrained activity following isoxsuprine treatment was significantly greater than control activity for 105 min after treatment. There was an apparent, although statistically nonsignificant, increased cutaneous blood flow resulting in visible water vapour and sweat production 5-60 min after administration. Initially, there was no difference in skin temperature between control and isoxsuprine treatment values; however, skin temperature decreased below control values 45-120 min after injection. Concurrently, there was a significant decrease in rectal temperature reflecting a decrease in body core temperature. Using infrared thermography, a significant decrease in superficial skin temperature of the front legs occurred 30-240 min after treatment. Isoxsuprine also reduced smooth muscle tone, which was apparent by decreased tone of the internal anal sphincter 10-180 min after treatment. It was concluded that the measurable pharmacological effects of i.v. isoxsuprine are short lived, since none of the above responses were apparent 4 h or more after i.v. administration.

The effect of spironolactone on the rat uterus

Our experimental study showed that in a dose related manner SP has successful inhibitory effect on the rat uterine horn, and also on the smooth muscle organs; ileum and trachea. We guess that SP can be used in well regulated dosed with least side effects to arrest preterm labor on human being in the future. Up to date there is no manuscript about contraction inhibitory effect of SP on the uterus. We hope this study will be of scientific help.

Prolonged presence of isoxsuprine in equine serum after oral administration

1. Isoxsuprine [1-(4-hydroxyphenyl)-2-(1-methyl-2-phenoxyethylamino)-1- propanol] serum concentrations after single- and multiple-dose administration to horse were investigated using immunoenzymatic ELISA, HPLC-UV and thermospray HPLC-MS methods. 2. Using HPLC-MS, isoxsuprine was detected up to 72 h after a single administration (1.2 mg/kg by gastric probe) and up to 96 h after the end of serial administration (1.2 mg/kg every 12 h for 7 days). 3. ELISA detected the drug up to 96 h after a single dose and up to 6 days after the end of prolonged administration. 4. Isoxsuprine is present in horse serum almost totally in conjugated form very likely as glucuronide. 5. It is concluded the administration of this drug must be suspended much earlier than previously presumed if race horse antidoping tests for the drug are to be negative.

Screening and confirmatory analysis of beta-agonists, beta-antagonists and their metabolites in horse urine by capillary gas chromatography-mass spectrometry

A method for the screening and confirmatory analysis of beta-agonists and -antagonists in equine urine is described. Following initial enzymic hydrolysis, the basic drugs and metabolites are extracted using Clean Screen DAU or Bond Elut Certify cartridges, and analysed as their trimethylsilyl ether or 2-(dimethyl) silamorpholine derivatives by capillary gas chromatography-mass spectrometry. The method proved to be very sensitive and selective for basic drugs. After administration of therapeutic doses of propranolol, metoprolol, timolol, isoxsuprine and clenbuterol to thoroughbred horses, the parent compound/metabolites could be detected in urine for upto 14-120 h depending on the drug.

The evaluation of isoxsuprine hydrochloride for the treatment of navicular disease: a double blind study

A randomised double-blind clinical trial of 28 horses was undertaken to evaluate the efficacy of isoxsuprine hydrochloride at four different doses:- 0.0 mg/kg bodyweight (bwt) (placebo), 0.6 mg/kg bwt, 1.2 mg/kg bwt and 1.8 mg/kg bwt for treatment of navicular disease. The results showed that horses treated with isoxsuprine hydrochloride (N = 22) responded significantly with respect to clinical assessment score (P less than 0.01) when compared with the control group (N = 6). Furthermore, there were no dose-related differences in the responses of the horses treated with increasing levels of isoxsuprine. No correlation was found between radiological evidence of the extent of navicular disease and severity of lameness or response to treatment.

Cardiovascular and pharmacokinetic effects of isoxsuprine in the horse

Isoxsuprine (0.6 mg/kg) administered IV to 6 standing horses produced substantial, transient decreases in systemic blood pressure, systemic vascular resistance, and stroke volume. It also produced substantial, transient increases in heart rate, cardiac output, and purposeful movement. Plasma concentrations of isoxsuprine peaked soon after the drug was administered IV and then decreased over a 12-hour period in a biexponential manner, with distribution and elimination half-lives of 14 minutes and 2.67 hours, respectively. Total body clearance and steady-state volume of distribution were calculated to be 53.8 ml/min/kg and 10.5 L/kg, respectively. When a recommended therapeutic dosage regimen (0.6 mg/kg 2 times a day, per os) was used in 4 of these horses, changes were not detected. Isoxsuprine was not detected in plasma after the drug was given orally. We conclude that 0.6 mg of isoxsuprine/kg given orally every 12 hours is not likely to produce cardiovascular changes in the resting horse and that this is probably because plasma concentrations are not high enough to do so.

Treatment of premature labor in insulin-dependent diabetic women

This retrospective study was designed to analyze the safety and efficacy of beta-sympathomimetic agents used to treat premature labor in insulin-dependent diabetic women. The study evaluated 12 insulin-dependent diabetic women who experienced 15 pregnancies complicated by premature labor. A group of 30 insulin-dependent diabetic women who delivered at term served as matched controls. Treatment consisted of parenteral and oral administration of beta-sympathomimetic drugs (ritodrine and isoxsuprine). Premature labor was diagnosed, and tocolytic treatment was initiated at a mean gestational age of 31.5 +/- 0.9 weeks. The mean gestational age at the time of delivery was 35.8 +/- 0.5 weeks. Delivery was delayed in the study group by a mean of 30.5 +/- 6.6 days. No fetal or infant deaths occurred in the study group, and there was no difference between the two groups in the incidence of neonatal morbidity. No maternal complications occurred. There were no significant differences in hemoglobin A1 levels between the two groups at any period of gestation. Thus, beta-sympathomimetic drugs may be used safely to treat premature labor in patients with insulin-dependent diabetes, provided they are administered under strictly controlled clinical settings.

Pharmacologic action of isoxsuprine in cutaneous and myocutaneous flaps

The therapeutic effects of isoxsuprine on skin capillary blood flow and viability were studied in arterial buttock flaps, latissimus dorsi myocutaneous flaps, and random skin flaps in pigs. It was observed that parenteral isoxsuprine increased capillary blood flow to the skin of arterial buttock flaps and the skin and muscle of latissimus dorsi myocutaneous flaps in a dose-response manner, with a maximum vascular effect observed at 1.0 mg/kg. However, this maximum effective dose of isoxsuprine did not have any significant effect on skin viability in the cutaneous and myocutaneous flaps compared with the control. Examination of the distribution of capillary blood flow within the flaps at varying distances from the pedicle revealed that isoxsuprine did not increase capillary blood flow or perfusion distance in the distal portion of the skin of arterial buttock flaps, latissimus dorsi myocutaneous flaps, and random skin flaps. The increased capillary blood flow as a result of isoxsuprine treatment was limited only to the arterial portion of the arterial buttock flaps and latissimus dorsi flaps. Therefore, it is concluded that isoxsuprine alone is not effective in augmentation of skin viability in cutaneous and myocutaneous flaps. The pharmacologic action of isoxsuprine on the vasculature in the skin and muscle of flaps was also discussed.

Effects of intra-amniotic isoxsuprine on amino acid placental transfer in rats

Direct administration of isoxsuprine to the rat fetus increases placental transfer of 35S-methionine and this increase is statistically significant on day 17 as compared with intraperitoneal administration and controls (p less than 0.01; p less than 0.05). In contrast, no statistically significant differences were found between the groups on day 16.

Drug treatment and flap survival

Some investigators found that isoxsuprine, propranolol, or heparin would increase skin-flap survival in loose-skinned animals. We evaluated the effects of these three drugs in the pig, an animal with skin circulation similar to that of humans. Four hundred ventrally based skin flaps that have a proximal axial portion and a distal random portion were made on the flanks of 40 pigs. There were eight study groups: control, isoxsuprine preoperatively and postoperatively, propranolol preoperatively and postoperatively, isoxsuprine postoperatively only, propranolol postoperatively only, heparin, single-stage surgical delay, and two-stage surgical delay. Flap survival was improved by the two-stage surgical delay when compared with the control flaps, flaps from pigs receiving a drug, or flaps from pigs having a single-stage surgical delay (p less than 0.001). When compared with the control flaps, neither isoxsuprine, propranolol, heparin, nor single-stage surgical delay significantly increased flap survival.

Pulmonary edema associated with isoxsuprine therapy

A 0.5% incidence of pulmonary edema was observed when the records of 1,407 patients treated with parenteral isoxsuprine over a 7-year interval were reviewed. Drug infusion rates were within the normal range in the seven affected patients. Discontinuation of therapy, oxygenation, and the administration of diuretics with or without digoxin were successful in reversing the process in all cases. Anemia, multiple gestation, and excessive intravenous fluids were identified as possible risk factors.

Augmentation of surviving flap area by intraarterial vasodilators administered through implantable pumps

Using the implantable Infusaid Model 300 pump, several vasodilators (prostaglandin E1, isoxsuprine, bradykinin, trimethaphan, and reserpine) were infused intraarterially into an abdominal island flap in the rabbit. All produced a large increase in flap surviving area over saline controls at forty-eight hours, measuring as high as a 2.8-fold increase in random portions of the flap with prostaglandin E1. The agents possessed differing modes of action but had the common property of vasodilatation. The results raise questions concerning the possible physiological role of endogenous prostaglandins in the surgical delay phenomenon. The Infusaid pump was a valuable tool in the study and was well tolerated by the animals.

Studies on isoxsuprine hydrochloride for the treatment of navicular disease

A peripheral vasodilating agent, isoxsuprine hydrochloride, administered as an oral paste, was evaluated to determine its efficacy for the treatment of navicular disease. In a clinical trial, 13 horses with navicular disease were treated at a dose rate of 0.6 mg/kg body weight (bwt) twice daily for periods of six to 14 weeks. Twelve of the horses became completely sound while being treated, although two required a 50 per cent increase in dose. Nine of the horses have remained sound two to 10 months after ceasing therapy. In a controlled randomised double blind clinical trial, 16 horses with navicular disease were assigned to treatment with either a placebo paste or isoxsuprine paste for three weeks and then re-examined. All the horses treated with isoxsuprine showed improvement in gait, with seven of eight horses becoming sound, whereas only two horses treated with a placebo paste showed slight improvement. This difference in response was highly significant (P less than 0.001). To evaluate any physiological and biochemical effects of isoxsuprine, it was administered to five Standardbred geldings at dose rates of 0.6 mg/kg bwt and 1.2 mg/kg bwt. Complete blood counts, routine plasma biochemical parameters, cardinal signs and blood pressure measurements were performed up to 24 h after a single dose. No significant change in any of these parameters was found. To assess the peripheral vasodilatory action of isoxsuprine, infra-red thermography of the lower limb was performed before and up to 8 h after administration to horses. This revealed a significant increase in distal limb temperature which occurred from 90 to 480 mins after isoxsuprine administration. The maximum mean increase in distal limb temperature was 3.1 degrees C and this occurred 4 h after administration of the drug.

Pulmonary edema occurring after isoxsuprine and dexamethasone treatment for preterm labor: Case report

A case of maternal pulmonary edema occurring in a patient in the 32nd week of gestation is presented. This was our first case of pulmonary edema seen during a period of five years' usage of isoxsuprine in the treatment of premature labor. The patient presented was 28 years old, gravida 2, para 1, admitted to the maternity ward with premature uterine contractions. Her past history eliminate cardiac or pulmonary disease. Isoxsuprine therapy was begun with initial dose of 0.04 mg/min. and increased to 0.32 mg/min., the total dose administered was 560 mg during 48 hours. During this period she was given in dexamethasone 24 mg. Fluid balance on the first day of the treatment was +1.7 liters and on the second day +5.2 liters. Forty-eight hours from the commencement of the treatment, the patient experienced shortness of breath and chest pain. Physical examination disclosed wet rales over both lungs, sinus tachycardia and tachypnea. Laboratory examination disclosed hypopotassemia of 3 mEq/liter, hypoxemia (PO2 of 80 torr on 0.5 FiO2 face mask) with mild hyperventilation 28 torr PCO2 with normal ph 7.43. Recognition of the early signs of pulmonary edema enable swift clinical diagnosis and steps to be taken to prevent disasterous condition due to progressive hypoxemia. The prompt treatment in this complication includes discontinuation of isoxsuprine and fluid administration, placement of the patient in an erect position, intravenous furosemid 40 mg, oxygen supplement by face mask and 25 mg of meperidine. The patient's condition dramatically improved though the lung fields became completely clear from wet rales only eight hours from the start of dyspneic attack.(ABSTRACT TRUNCATED AT 250 WORDS)

Sublingual and oral isoxsuprine in patients with Raynaud's phenomenon

Oral and sublingual isoxsuprine 20 mg were compared with placebo in double blind randomised cross over trial in 7 patients with Raynaud's phenomenon. Skin thermography, plethysmography of the finger tips and direct temperature measurements showed that sublingual isoxsuprine was slightly but consistently superior to the oral form and to placebo; no significant difference was observed between the latter two treatments. It is concluded that sublingual administration of isoxsuprine has advantages over their routes of administration, and that thermography is a suitable technique for qualitative, but less appropriate for quantitative, measurement of drug effects in patients with Raynaud's phenomenon.

Experience with isoxsuprine in the treatment of sickle cell crisis: a proposed mechanism of action

An accidental clinical observation triggered this investigation into the possible beneficial effects of isoxsuprine in the treatment of painful sickle cell crisis. Twenty-four patients were studied with a total of 34 episodes of painful crisis. As they had all been previously treated by us we knew the duration of their crisis under conventional treatment, so that the two regimens with and without isoxsuprine could be compared. Isoxsuprine was administered in 3 successive steps: (1) as an IM injection (5-10 mg), (2) as a rapid IV infusion (1 mg/minute), and (3) as a slow, continuous IV infusion, (0.1-0.3 mg/minute). The results from this study suggest that isoxsuprine exerts in fact a remarkable action in sickle cell crisis by bringing about prompt relief in approximately 80% of the cases within 5 hours, and in 40% of the cases within 2 hours. There were only 2 cases of absolute failure. The hospitalization time was remarkably reduced and the use of narcotics was minimized. Side effects (tachycardia, palpitations, somnolence) have been observed mainly in cases where relatively high doses of isoxsuprine had to be administered IV.

Effects of isoxsuprine on maternal and fetal acid-base balance and circulation

Prematurity is a large contributing factor to neonatal morbidity. An obstetric alternative to premature labor is administration of isoxsuprine, an effective inhibitor of uterine contractions. Six crossbred unanesthetized pregnant ewes were used to determine the effects on fetal and maternal cardiovascular and acid-base status of 10 maternal intravenous infusions of 30 mg isoxsuprine over 30 minutes (1 mg/min). Isoxsuprine caused slight maternal hypotension and a transient acidosis, both of which returned to baseline values within 60 minutes. Maternal tachycardia persisted throughout the experiment. A slight decrease in the oxygen percent saturation of the hemoglobin and the calculated O2 content was observed after the infusion. There was no significant change in uterine blood flow. Maternal lactate concentration transiently increased at 60 minutes only. In the fetus, isoxsuprine caused transient hypotension and tachycardia. Fetal arterial PCO2, calculated bicarbonate concentration, and O2 content all decreased slightly at 45 minutes only. Fetal hyperglycemia was observed after the infusion throughout the experiment. All other fetal values returned to baseline levels within 60 minutes. It is suggested that 30 mg isoxsuprine can cause tolerable maternal and fetal metabolic and physiologic effects when administered intravenously to the unanesthetized pregnant ewe.

Isoxsuprine infusion in the rat: alterations in maternal, fetal and neonatal glucose homeostasis

To determine the mechanism of alteration in glucose homeostasis associated with maternal isoxsuprine administration, isoxsuprine or 0.04 M saline was administered intravenously for 3 hours to term pregnant and age-matched virgin rats. Isoxsuprine infusion significantly increased plasma glucose and insulin concentrations and decreased hepatic glycogen stores in both. Compared to rat pups of saline infused mothers, pups of isoxsuprine infused mothers had significantly elevated plasma glucose concentrations for the first 4 hours of life and plasma insulin concentrations for the first two. Plasma glucose concentrations for the offspring of isoxsuprine treated mothers then decreased significantly and remained so until 16 hours of age. Hepatic glycogen concentrations were significantly less in rat pups of isoxsuprine treated mothers at birth and for the first 4 hours of life. In a limited number of studies, isoxsuprine was present at birth in substantial quantities (80-85% of maternal levels) in the plasma of rat pups of isoxsuprine infused mothers. These data suggest that maternal isoxsuprine therapy mobilizes hepatic glycogen and results in maternal hyperlgycemia. Maternal isoxsuprine infusion may directly deplete fetal hepatic glycogen and result in transient fetal and neonatal hyperglycemia. the in utero depletion of glycogen and possibly, the early stimulation of insulin production may be responsible for the later significant decreases in plasma glucose in the offspring of isoxsuprine treated mothers.

A study of the treatment time necessary for the vasodilator drug isoxsuprine to prevent necrosis in a skin flap

These results show that administration of isoxsuprine at least 13 days prior to flap elevation and continuance at least 7 days postoperatively does lead to completre survival of the abdominal neurovascular island skin flap in the rat.

Isoxsuprine infusion to the pregnant rabbit and its effect on fetal lung surfactant

Rabbit does, pregnant on the 28th day, were infused with isoxsuprine 2.5 mg/kg body weight/h in 50 ml 5% glucose, or with glucose only. The isoxsuprine caused maternal heart rate to increase and blood pressure, mean and diastolic, to decrease. The volume of fetal pulmonary fluid (FPF) and the wet lung weight/body weight ratio were significantly lowered by isoxsuprine. Lecithin/sphingomyelin ratio of FPF in isoxsuprine-infused animals was higher, compared with controls, not infused. Minimal surface tension of FPF, evaluated with pulsating bubble, was significantly lower in treated fetuses. Histologic examination of the fetal lungs after fixation with potassium dichromate and mercuric chloride showed that in isoxsuprine-treated litters FPF contained more granular and sudanophilic material. The results offer further evidence that isoxsuprine causes dehydration of fetal lungs and a release of pulmonary surfactant.

Effects of intravenous isoxsuprine and ritodrine, with and without concomitant dexamethasone, on fetoplacental and pituitary hormones and cyclic adenosine monophosphate during late pregnancy

Beta sympathomimetic drugs are used to inhibit preterm labor and glucocorticoids to accelerate fetal pulmonary maturation. A study was designed to investigate the hormonal effects of intravenous infusion of isoxsuprine 150 to 200 mcg. per minute or ritodrine 100 to 150 mcg. per minute in a series of 28 women at 28 to 40 weeks' gestation, with and without concomitant dexamethasone therapy. Serial serum samples taken before and during the six hours of infusion were assayed for cyclic adenosine-3,5-monophosphate (AMP), estradiol, estriol, progesterone, human placental lactogen (hPL), thyrotropin (TSH), follicle-stimulating hormone (FSH), and human growth hormone (gGH). Ritodrine was more potent than isoxsuprine in increasing the circulating levels of cyclic AMP. The levels of placental steroid hormones decreased slightly, as did the ratio of progesterone to estradiol. Human placental lactogen and pituitary hormones showed no consistent changes. Simultaneous administration of dexamethasone did not modify these results.

[Influence of isoxsuprine HCl on blood viscosity]

A decrease of blood viscosity is a working principle in the therapy of severe disorders of arterial blood flow. Isoxsuprine-HCl was found effective in lowering the blood viscosity when given intravenously in a dose of 30 mg over 60 min. This effect derives probably from a decrease of the tendency to aggregate and an increase of the flexibility of red blood cells. 30 min after termination of the infusion this effect has its maximum and 60 min later still is significantly raised.

The use of isoxsuprine in essential dysmenorrhea. A controlled clinical study

The "uterus-specific" beta-adrenoceptor stimulator isoxsuprine was used for the treatment of primary dysmenorrhea in a double-blind controlled clinical study. No significant beneficial effect of the drug was evident.

Treatment of imminent premature labour

In this study, 194 imminent premature deliveries were treated. The pregnancies were in the 28th to 36th week. Uterine contractions were demonstrable in all patients and amniotic membranes were intact. All patients were treated with bedrest. Two betasympathomimetics were used in a double-blind study: Nyldrin hydrochloride (43 cases) and Isoxuprine hydrochloride (60 cases). A placebo was given to 41 patients, and ethyl alcohol to 50 patients. Intravenous and intramuscular treatment given in the hospital was continued with oral administration at home, and follow-up examinations were repeated at short intervals. Taking a minimum birth weight of 2500 g as the criteria of successful treatment, the success rate in the placebo group was 71%, in the Nylidrin hydrochloride group 86%, the Isoxuprine hydrochloride group 75% and the alcohol group 70%. When premature delivery was postponed 7 days, the pregnancy advanced., to the 37th week or later in 73, 77, 62 and 56% in their respective groups. The beta-sympathomimetics, especially the Nylidrin hydrochloride, were in every respect more efficient than placebo or alcohol. The therapeutic effect of alcohol was no better than that obtained with placebo. From the fetal point of view, the drugs used in the present study showed no adverse-effects.

Isoxsuprine as an oral vasodilator

The effect of isoxsuprine, administered orally as a single 20-mg tablet, was compared with that of a placebo in a double-blind crossover study in 12 volunteers with and in 12 without peripheral vascular disease. Isoxsuprine failed to increase blood flow in the calf, foot or hand, and did not alter blood pressure or heart rate significantly. Claudication time was not prolonged after taking the drug. This study does not support the value of oral administration of isoxsuprine as a peripheral vasodilator.