Pharmacokinetics and metabolism of salbutamol in premature labour.

Abstract

1 The pharmacokinetics of salbutamol and its sulphate conjugate were examined during intravenous and steady‐state oral administration in nine patients receiving the drug for the prevention or treatment of premature labour. 2 Uterine contractions were inhibited by plasma salbutamol concentrations in the range 8‐33 ng ml‐1 in six of the seven patients who were receiving intravenous drug. 3 By comparison with our previous study in a control group of healthy males and nonpregnant females, the total clearance of salbutamol in premature labour (501; s.d. 185 ml min‐1) was similar to that in the control group (480; s.d. 123 ml min‐1). Renal salbutamol clearance (208; s.d. 51 ml min‐1), however, was significantly less than that in the control group (283; s.d. 51 ml min‐1). 4 The systemic availability (n = 3), urinary recovery of unchanged oral salbutamol and area under the plasma curve during the oral dosage interval (n = 5) were all only slightly lower (10‐20%) than control values, suggesting slightly lower oral absorption. 5 Formation and elimination of the sulphate conjugate were similar to those observed in control subjects suggesting that first‐ pass sulphation in the gut wall is unchanged in pregnancy. Overall there were only minor differences in salbutamol pharmacokinetics between control subjects and patients in premature labour.

Pregnancy‐related pharmacokinetic changes

“…There are limited data available on the effects of pregnancy on oral bioavailability. However, small alterations have been reported for multiple drugs, such as artesunate (23% decrease), salbutamol (10–20% decrease), and metformin (14% increase), whereas others demonstrate no change (e.g., cephradine, propranolol, sotalol, and ampicillin).…”

Determination of the relative bioavailability of salbutamol to the lung following inhalation [see comments]

“…Measurement of the ester sulphate conjugate Urine samples were extracted before and after hydrolysis with HCl using a method based on that of Hutchings (1986). Hydrochloric acid 0.1 M was used to prevent elution of salbutamol from the solid phase columns.…”

Nano-Vesicles of Salbutamol Sulphate in Metered Dose Inhalers: Formulation, Characterization and in Vitro Evaluation

“…Also, Anti-asthmatic drugs have high potential to induce toxic side effects after parenteral administration; stimulation of beta receptors, occur in the body. This effect results in cardiac stimulation by receptors and peripheral vasodilatation and hypotension [11]. The aforementioned facts directed our interest to design a new nano-based SS MDI according to the USP guidelines to reduce the uptake of SS by β1…”