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Glycopyrrolate, like other anticholinergic (antimuscarinic) agents, inhibits the action of acetylcholine on structures innervated by postganglionic cholinergic nerves and on smooth muscles that respond to acetylcholine but lack cholinergic innervation. These peripheral cholinergic receptors are present in the autonomic effector cells of smooth muscle, cardiac muscle, the sinoatrial node, the atrioventricular node, exocrine glands and, to a limited degree, in the autonomic ganglia. Thus, it diminishes the volume and free acidity of gastric secretions and controls excessive pharyngeal, tracheal, and bronchial secretions.
Glycopyrrolate antagonizes muscarinic symptoms (e.g., bronchorrhea, bronchospasm, bradycardia, and intestinal hypermotility) induced by cholinergic drugs such as the anticholinesterases.
The highly polar quaternary ammonium group of glycopyrrolate limits its passage across lipid membranes, such as the blood-brain barrier, in contrast to atropine sulfate and scopolamine hydrobromide, which are highly non-polar tertiary amines which penetrate lipid barriers easily.
With intravenous injection, the onset of action is generally evident within one minute. Following intramuscular administration, the onset of action is noted in 15 to 30 minutes, with peak effects occurring within approximately 30 to 45 minutes. The vagal blocking effects persist for 2 to 3 hours and the antisialagogue effects persist up to 7 hours, periods longer than for atropine.
The following pharmacokinetic information and conclusions were obtained from published studies that used nonspecific assay methods.
Distribution: The mean volume of distribution of glycopyrrolate was estimated to be 0.42 ± 0.22L/kg.
Metabolism: The in vivo metabolism of glycopyrrolate in humans has not been studied.
Excretion: The mean clearance and mean T1/2 values were reported to be 0.54 ± 0.14 L/kg/hr and 0.83 ± 0.13 hr, respectively post IV administration. After IV administration of a 0.2 mg radiolabeled glycopyrrolate, 85% of dose recovered was recovered in urine 48 hours postdose and some of radioactivity was also recovered in bile. After IM administration of glycopyrrolate to adults, the mean T1/2 value is reported to be between 0.55 to 1.25 hrs. Over 80% of IM dose administered was recovered in urine and the bile as unchanged drug and half the IM dose is excreted within 3 hrs. The following table summarizes the mean and standard deviation of pharmacokinetic parameters from a study.
(µg/L • hr)
|(6 µg/kg IV)||0.83±0.27||0.42±0.22||0.54±0.14||-||-||8.64±1.49**|
|(8 µg/kg IM)||-||-||-||27.48±6.12||3.47±1.48||6.64±2.33**|
| *0-12 hr
Gender: Gender differences in pharmacokinetics of glycopyrrolate have not been investigated
Renal Impairment: In one study glycopyrrolate was administered IV in uremic patients undergoing renal transplantation. The mean elimination half-life was significantly longer (46.8 minutes) than in healthy patients (18.6 minutes). The mean area-under-the-concentration-time curve (10.6 hr-µg/L), mean plasma clearance (0.43 L/hr/kg), and mean 3-hour urine excretion (0.7%) for glycopyrrolate were also significantly different than those of controls (3.73 hr-µg/L, 1.14 L/hr/kg, and 50%, respectively). These results suggest that the elimination of glycopyrrolate is severely impaired in patients with renal failure.
Hepatic Impairment: Pharmacokinetic information in patients with hepatic impairment is unavailable.
Pediatrics: Following IV administration (5 µg/kg glycopyrrolate) to infants and children, the mean T ½ values were reported to be between 21.6 and 130.0 minutes and between 19.2 and 99.2 minutes, respectively.
Last reviewed on RxList: 12/12/2007
This monograph has been modified to include the generic and brand name in many instances.
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