European Journal of Clinical Pharmacology © by Springer-Verlag 1978
Europ. J. clin. Pharmacol. 14, 95-99 (1978)
Metabolic Effects of Oral Salbutamol in Late Pregnancy N. O. Lunell, J. Wager, B. B. Fredholm, and B. Persson Department of Obstetrics and Gynecology,HuddingeUniversityHospital, Department of Pharmacology,KarolinskaInstitute and Department of Pediatrics, St. G6rans Hospital, KarolinskaInstitute, Stockholm,Sweden
Summary. Ten women in late pregnancy were given an oral dose of salbutamol 4 mg. Heart-rate and blood-pressure were recorded and blood-samples for measurement of cyclic AMP, C-peptide, glucose, lactate, glycerol, non-esterified fatty acids (NEFA) and fl-hydroxybutyrate (3-HB) were collected every 30 min for 120 min. In seven of the women the same experiment was performed without the salbutamol. After salbutamol maternal heart-rate was significantly increased at 30 and 90min, and diastolic blood-pressure was significantly decreased between 30 and 120 min; systolic blood-pressure was unaltered. Plasma cyclic AMP was significantly increased by salbutamol at 30 and 120 min and C-peptide at 60 min. Plasma glucose was significantly elevated 60 min after salbutamol and glycerol after 90 min. Plasma NEFA and 3-HB increased both with and without the drug, with a tendency towards higher levels in the group that received salbutamol. Lactate levels were unchanged after salbutamol and fell when the drug was not given, but the difference was not significant. The results show clear circulatory and metabolic effects of a single clinical dose of salbutamol. Key words: Salbutamol, metabolic effects, cyclic AMP, fl-adrenergic agonist, pregnancy, carbohydrate metabolism, lipid metabolism.
Selective /~-adrenoceptor agonists, such as salbutamol, are widely used to stop or to prevent premature labour. In order to stop premature labour intravenous salbutamol is given in high doses, generally under well-controlled circumstances. For prevention of premature labour oral salbutamol may be
given, often for long periods of time, to ambulant patients. Intravenous salbutamol given to women in the last trimester of pregnancy has caused tachycardia and increased systolic and decreased diastolic bloodpressure (Lunell, et al., 1976; McDewitt et al., 1975). Intravenous salbutamol also produced marked metabolic alternations (Lunell et al., 1977; Thomas et al., 1977; Fredholm et al., 1978); there was a dose dependent elevation of plasma cyclic AMP, insulin, C-peptide, glucose, glycerol, nonesterfied fatty acids (NEFA) and fl-hydroxybutyrate (3-HB) (Lunell et al., 1977; Fredholm et al., 1978). The effect of oral salbutamol has twice been investigated. Taylor and co-workers (1976) found that normal, nonobese men responded with a rapid increase in plasma insulin and a more delayed rise in glucose, NEFA and glycerol following a single oral dose of salbutamol 4 mg. Blouin and co-workers (1976) studied the effect of another fl2-adrenoceptor agonist, ritodrine, on maternal and fetal carbohydrate metabolism. They found that ten weeks of treatment with this drug had no significant effect on insulin levels or on glucose tolerance. There are, however, no data available about the effect of acute administration of oral fi2-adrenoceptor stimulants in late pregnancy. The present study was an investigation of the metabolic and circulatory effect of an oral dose of salbutamol in late gestation.
Material and Methods Patients
Ten women participated in the study, which was approved by the regional Ethical Committee. All 0031-6970/78/0014/0095/$01.00
96
N.O. Lunell et al.: Salbutamol in Late Pregnancy
Table 1
Mother Subject Age
Infant Height (cm)
Prepregn, weight (kg)
Weight Previously gain treated with (kg) salbutamol
Gest. age at testing (days)
Birth weight (g)
Length G e s t . (cm) age (days)
Apgar score 1'5'
Clinical course
50 48 46 48 46 43 46
246
9:9 10:10 9:9 9:10 4:6:10 8:10 9:10
uneventful uneventful tmeventful uneventful uneventful uneventful uneventful
50 50 47 49
266 230 260 254
6:8 10:10 8:10 9:10
uneventful uneventful SFD a uneventful
1. 2. 3. 4. 5.
26 25 18 35 32
167 163 165 173 172
60 59 58 66 60
4.3 8.0 16.0 9.9 16.9
yes yes yes yes yes
221 261 240 240 228
6.
29
160
44
10.0
no
203
Cf3030 Cf3190 Cf2760 93160 92450 92140 92330
7. 8. 9. 10.
22 22 24 23
172 162 167 163
64 70 92 60
9.0 3.5 2.7 14.6
yes yes no yes
244 205 235 201
Cf3810 Cf2920 92230 92630
Zo
"~
293 264 241 259 267
a SFD = small for date
received a single oral dose of salbutamol 4 mg in the morning after fasting overnight. Blood samples were collected and cardiovascular measurements were made as described below. In seven of the women the same experiment was performed without the drug. Clinical details of the women and their newborn infants are given in Table 1. As shown in the table, the women formed a heterogenous group, because four were diabetic (2 of whom were gestational diabetics) and six were not diabetic. Because of premature contractions eight of the women had been treated with oral salbutamol in doses between 2 and 4 mg, 4 to 6 times a day, for a period from 1 to 8 weeks before the study. Two of the women had not previously received salbutamol. All women, except subjects 6, 8 and 9, had a normal weight in relation to heigth. Procedure
An indwelling catheter in one brachial vein was used to obtain blood samples for measurement of cyclic AMP, C-peptide, glucose, lactate, glycerol, NEFA and 3-HB. After blood samples had been collected at - 2 0 min and 0 min, the patient received oral salbutamol 4 mg, and further blood samples were taken at 30, 60, 90 and 120min. Fetal heart rate was continously monitored with a cardiotachometer (Corometrics, USA). Maternal blood-pressure and puls rate were recorded every five minutes. In seven women the same experiment was performed without the drug. For lactic acid determination samples were drawn directly into ice-cooled 0.6 N perchloric acid. Cyclic AMP was determined in blood samples collected into tubes containing EDTA. Blood for the
other parameters was taken into heparin-containing tubes. After centrifugation the plasma or protein free supernatant was stored frozen until assayed. Chemical Determinations
All determinations were done in duplicate. Lactic acid was measured according to Cramp (1968), glucose by a glucose oxidase method (Glox ®, AB Kabi, Stockholm, Sweden), glycerol fluorometrically (Laurell and Tibbling, 1967), 3-HB fluorimetrically (Persson, 1969), C-peptide by radioimmunoassay (Heding, 1975) with reagents obtained from Novo Research Institute (Copenhagen, Denmark). Cyclic AMP was determined essentially according to Brown et al. (1972), using binding protein from bovine adrenal cortex. (3H)-adenosine 3', 5'-cyclic monophosphate (27Ci/mmol) was obtained from the Radiochemical Centre (Amesham, England). The assay mixture contained NaCI 0.1 mol/1 and 0.1% bovine serum albumin to minimize the influence of salts and protein in the samples, and 5mM EDTA to inhibit phosphodiesterase. The samples were measured either undiluted or diluted 1:5 in assay buffer, as the results were identical. Phosphodiesterase treatment (Boehringer, Mannheim, BRD) could remove 92 _+ 6 per cent of the binding activity. Statistical Evaluation
The means (~) and standard error of the mean (s~) was computed conventionally. Statistical hypotheses were tested by the Wilcoxon test for paired or unpaired variates. Covariation was tested by Spearman's non-parametric rank correlation, p < 0.05 was
N. O. Lunell et al.: Salbutamol in Late Pregnancy
97
considered to represent a statistically significant difference. .
8-
Results
Heart rate
Beat s ~ i n
I
Cardiovascular Responses Following oral salbutamol, diastolic blood pressure fell significantly between 30 and 120 min (Fig. 1). The mean maximal decrease was 8 m m H g (11%) from a mean basal value of 74 _+ 3.6 mmHg. Systolic blood pressure was unaltered. Maternal heart rate was increased significantly at 30 and 90 rain by 5 beats/min (6%) from a mean basal value of 80 + 3.5 beats/min (Fig. 1). In the controls there was a decrease in maternal heart rate, probably due to rest.
/
\
&-__I
I
"4_5
-4 d 8mmHg
3'0
6'0
9'0
Diastolic BP "
"
liOmln.
5
Cyclic A.~IP (Fig. 1) A significant increase in cyclic A M P was found 30 and 1 2 0 m i n after salbutamol. The maximal mean increase was 4.9 nmol/1 (28%) from the mean basal value of 17.5 _+ 2.8 nmol/1. Cyclic-AMP in the controls was unchanged.
-8
6
6
3'0
l i 0 mln.
9'0
120 mln.
CAMP
/
\
/
T h e r e was a significant increase in C-peptide 60 rain after salbutamol. The maximal increase was 0.097 nmol/1 (21%) from the mean basal value 0.466 _+ 0.093 nmol/1. In the controls there was a slight but non-significant decrease in C-peptide.
\
/
\I/
/
3'0
Glucose and Lactate (Fig. 2) 0.2"
n mo~/I C-peptid
6'0 .
0.1"
J O"
\
/ /
\\I,
Glycerol, NEFA and 3-HB (Fig. 2) Plasma glycerol increased significantly 90 min after salbutamol. The maximal mean increase was 0.0189 nmol/1 (29%) from the mean basal value of 0.064 _+ 0.003 nmol/1. There was no change in the controls. Plasma N E F A and 3-HB increased both after salbutamol and in the controls. There was a tendency to higher levels after salbutamol than in the controls, but the difference was not significant.
9'0
n m o~1
C-peptide (Fig. 1)
After salbutamol there was an increase in plasma glucose, which was significant at 30 min. T h e mean increase was 0.32 mmol/1 (8%) from the mean basal value of 4.16 _+ 0.27 mmol/1. There was no change in the controls. Plasma lactate did not change after salbutamol, but there was a tendency to a reduction in the controls (probably an effect of the fasting).
6'0
--I
'
Europ. J. clin. Pharmacol. 14, 95-99 (1978)
Metabolic Effects of Oral Salbutamol in Late Pregnancy N. O. Lunell, J. Wager, B. B. Fredholm, and B. Persson Department of Obstetrics and Gynecology,HuddingeUniversityHospital, Department of Pharmacology,KarolinskaInstitute and Department of Pediatrics, St. G6rans Hospital, KarolinskaInstitute, Stockholm,Sweden
Summary. Ten women in late pregnancy were given an oral dose of salbutamol 4 mg. Heart-rate and blood-pressure were recorded and blood-samples for measurement of cyclic AMP, C-peptide, glucose, lactate, glycerol, non-esterified fatty acids (NEFA) and fl-hydroxybutyrate (3-HB) were collected every 30 min for 120 min. In seven of the women the same experiment was performed without the salbutamol. After salbutamol maternal heart-rate was significantly increased at 30 and 90min, and diastolic blood-pressure was significantly decreased between 30 and 120 min; systolic blood-pressure was unaltered. Plasma cyclic AMP was significantly increased by salbutamol at 30 and 120 min and C-peptide at 60 min. Plasma glucose was significantly elevated 60 min after salbutamol and glycerol after 90 min. Plasma NEFA and 3-HB increased both with and without the drug, with a tendency towards higher levels in the group that received salbutamol. Lactate levels were unchanged after salbutamol and fell when the drug was not given, but the difference was not significant. The results show clear circulatory and metabolic effects of a single clinical dose of salbutamol. Key words: Salbutamol, metabolic effects, cyclic AMP, fl-adrenergic agonist, pregnancy, carbohydrate metabolism, lipid metabolism.
Selective /~-adrenoceptor agonists, such as salbutamol, are widely used to stop or to prevent premature labour. In order to stop premature labour intravenous salbutamol is given in high doses, generally under well-controlled circumstances. For prevention of premature labour oral salbutamol may be
given, often for long periods of time, to ambulant patients. Intravenous salbutamol given to women in the last trimester of pregnancy has caused tachycardia and increased systolic and decreased diastolic bloodpressure (Lunell, et al., 1976; McDewitt et al., 1975). Intravenous salbutamol also produced marked metabolic alternations (Lunell et al., 1977; Thomas et al., 1977; Fredholm et al., 1978); there was a dose dependent elevation of plasma cyclic AMP, insulin, C-peptide, glucose, glycerol, nonesterfied fatty acids (NEFA) and fl-hydroxybutyrate (3-HB) (Lunell et al., 1977; Fredholm et al., 1978). The effect of oral salbutamol has twice been investigated. Taylor and co-workers (1976) found that normal, nonobese men responded with a rapid increase in plasma insulin and a more delayed rise in glucose, NEFA and glycerol following a single oral dose of salbutamol 4 mg. Blouin and co-workers (1976) studied the effect of another fl2-adrenoceptor agonist, ritodrine, on maternal and fetal carbohydrate metabolism. They found that ten weeks of treatment with this drug had no significant effect on insulin levels or on glucose tolerance. There are, however, no data available about the effect of acute administration of oral fi2-adrenoceptor stimulants in late pregnancy. The present study was an investigation of the metabolic and circulatory effect of an oral dose of salbutamol in late gestation.
Material and Methods Patients
Ten women participated in the study, which was approved by the regional Ethical Committee. All 0031-6970/78/0014/0095/$01.00
96
N.O. Lunell et al.: Salbutamol in Late Pregnancy
Table 1
Mother Subject Age
Infant Height (cm)
Prepregn, weight (kg)
Weight Previously gain treated with (kg) salbutamol
Gest. age at testing (days)
Birth weight (g)
Length G e s t . (cm) age (days)
Apgar score 1'5'
Clinical course
50 48 46 48 46 43 46
246
9:9 10:10 9:9 9:10 4:6:10 8:10 9:10
uneventful uneventful tmeventful uneventful uneventful uneventful uneventful
50 50 47 49
266 230 260 254
6:8 10:10 8:10 9:10
uneventful uneventful SFD a uneventful
1. 2. 3. 4. 5.
26 25 18 35 32
167 163 165 173 172
60 59 58 66 60
4.3 8.0 16.0 9.9 16.9
yes yes yes yes yes
221 261 240 240 228
6.
29
160
44
10.0
no
203
Cf3030 Cf3190 Cf2760 93160 92450 92140 92330
7. 8. 9. 10.
22 22 24 23
172 162 167 163
64 70 92 60
9.0 3.5 2.7 14.6
yes yes no yes
244 205 235 201
Cf3810 Cf2920 92230 92630
Zo
"~
293 264 241 259 267
a SFD = small for date
received a single oral dose of salbutamol 4 mg in the morning after fasting overnight. Blood samples were collected and cardiovascular measurements were made as described below. In seven of the women the same experiment was performed without the drug. Clinical details of the women and their newborn infants are given in Table 1. As shown in the table, the women formed a heterogenous group, because four were diabetic (2 of whom were gestational diabetics) and six were not diabetic. Because of premature contractions eight of the women had been treated with oral salbutamol in doses between 2 and 4 mg, 4 to 6 times a day, for a period from 1 to 8 weeks before the study. Two of the women had not previously received salbutamol. All women, except subjects 6, 8 and 9, had a normal weight in relation to heigth. Procedure
An indwelling catheter in one brachial vein was used to obtain blood samples for measurement of cyclic AMP, C-peptide, glucose, lactate, glycerol, NEFA and 3-HB. After blood samples had been collected at - 2 0 min and 0 min, the patient received oral salbutamol 4 mg, and further blood samples were taken at 30, 60, 90 and 120min. Fetal heart rate was continously monitored with a cardiotachometer (Corometrics, USA). Maternal blood-pressure and puls rate were recorded every five minutes. In seven women the same experiment was performed without the drug. For lactic acid determination samples were drawn directly into ice-cooled 0.6 N perchloric acid. Cyclic AMP was determined in blood samples collected into tubes containing EDTA. Blood for the
other parameters was taken into heparin-containing tubes. After centrifugation the plasma or protein free supernatant was stored frozen until assayed. Chemical Determinations
All determinations were done in duplicate. Lactic acid was measured according to Cramp (1968), glucose by a glucose oxidase method (Glox ®, AB Kabi, Stockholm, Sweden), glycerol fluorometrically (Laurell and Tibbling, 1967), 3-HB fluorimetrically (Persson, 1969), C-peptide by radioimmunoassay (Heding, 1975) with reagents obtained from Novo Research Institute (Copenhagen, Denmark). Cyclic AMP was determined essentially according to Brown et al. (1972), using binding protein from bovine adrenal cortex. (3H)-adenosine 3', 5'-cyclic monophosphate (27Ci/mmol) was obtained from the Radiochemical Centre (Amesham, England). The assay mixture contained NaCI 0.1 mol/1 and 0.1% bovine serum albumin to minimize the influence of salts and protein in the samples, and 5mM EDTA to inhibit phosphodiesterase. The samples were measured either undiluted or diluted 1:5 in assay buffer, as the results were identical. Phosphodiesterase treatment (Boehringer, Mannheim, BRD) could remove 92 _+ 6 per cent of the binding activity. Statistical Evaluation
The means (~) and standard error of the mean (s~) was computed conventionally. Statistical hypotheses were tested by the Wilcoxon test for paired or unpaired variates. Covariation was tested by Spearman's non-parametric rank correlation, p < 0.05 was
N. O. Lunell et al.: Salbutamol in Late Pregnancy
97
considered to represent a statistically significant difference. .
8-
Results
Heart rate
Beat s ~ i n
I
Cardiovascular Responses Following oral salbutamol, diastolic blood pressure fell significantly between 30 and 120 min (Fig. 1). The mean maximal decrease was 8 m m H g (11%) from a mean basal value of 74 _+ 3.6 mmHg. Systolic blood pressure was unaltered. Maternal heart rate was increased significantly at 30 and 90 rain by 5 beats/min (6%) from a mean basal value of 80 + 3.5 beats/min (Fig. 1). In the controls there was a decrease in maternal heart rate, probably due to rest.
/
\
&-__I
I
"4_5
-4 d 8mmHg
3'0
6'0
9'0
Diastolic BP "
"
liOmln.
5
Cyclic A.~IP (Fig. 1) A significant increase in cyclic A M P was found 30 and 1 2 0 m i n after salbutamol. The maximal mean increase was 4.9 nmol/1 (28%) from the mean basal value of 17.5 _+ 2.8 nmol/1. Cyclic-AMP in the controls was unchanged.
-8
6
6
3'0
l i 0 mln.
9'0
120 mln.
CAMP
/
\
/
T h e r e was a significant increase in C-peptide 60 rain after salbutamol. The maximal increase was 0.097 nmol/1 (21%) from the mean basal value 0.466 _+ 0.093 nmol/1. In the controls there was a slight but non-significant decrease in C-peptide.
\
/
\I/
/
3'0
Glucose and Lactate (Fig. 2) 0.2"
n mo~/I C-peptid
6'0 .
0.1"
J O"
\
/ /
\\I,
Glycerol, NEFA and 3-HB (Fig. 2) Plasma glycerol increased significantly 90 min after salbutamol. The maximal mean increase was 0.0189 nmol/1 (29%) from the mean basal value of 0.064 _+ 0.003 nmol/1. There was no change in the controls. Plasma N E F A and 3-HB increased both after salbutamol and in the controls. There was a tendency to higher levels after salbutamol than in the controls, but the difference was not significant.
9'0
n m o~1
C-peptide (Fig. 1)
After salbutamol there was an increase in plasma glucose, which was significant at 30 min. T h e mean increase was 0.32 mmol/1 (8%) from the mean basal value of 4.16 _+ 0.27 mmol/1. There was no change in the controls. Plasma lactate did not change after salbutamol, but there was a tendency to a reduction in the controls (probably an effect of the fasting).
6'0
--I
'
