GLYRX-PF (Page 3 of 4)


GLYRX-PF is a synthetic anticholinergic agent. It is intended for intramuscular or intravenous administration. Each 1 mL contains 0.2 mg of glycopyrrolate, water for injection, sodium chloride as a tonicity agent, and hydrochloric acid or sodium hydroxide as pH adjusters. GLYRX-PF is preservative free.

Glycopyrrolate is a quaternary ammonium salt with the following chemical name: (RS)-[3-(SR)-Hydroxy-1,1-dimethylpyrrolidinium bromide] a-cyclopentylmandelate The molecular formula is C19 H28 BrNO3 and the molecular weight is 398.33.

Its structural formula is as follows:

(click image for full-size original)

Glycopyrrolate occurs as a white, odorless, crystalline powder. It is soluble in water and alcohol, and practically insoluble in chloroform and ether. It is completely ionized at physiological pH values. GLYRX-PF is a clear, colorless, sterile liquid with a pH of 2.0 – 3.0. The partition coefficient of Glycopyrrolate in n-octanol/water system is 0.304 (log10 P = -1.52) at ambient room temperature (24°C).


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12.1 Mechanism of Action

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.

12.2 Pharmacodynamics

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. For this reason, the occurrence of CNS-related side effects is lower, in comparison to their incidence following administration of anticholinergics which are chemically tertiary amines that can cross this barrier readily. 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.

12.3 Pharmacokinetics

The following pharmacokinetic information and conclusions were obtained from published studies that used nonspecific assay methods.


The mean volume of distribution of glycopyrrolate was estimated to be 0.42 ± 0.22 L/kg.



The in vivo metabolism of glycopyrrolate in humans has not been studied.


The mean clearance and mean t1/2 values were reported to be 0.54 ± 0.14 L/kg/hr and 0.83 ± 0.27 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 post dose and some of the 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.

0-8 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*

Specific Populations

Pediatric Patients:

Following IV administration (5 μg/kg glycopyrrolate) to infants and children, the mean t1/2 values were reported to be between 21.6 and 130.0 minutes and between 19.2 and 99.2 minutes, respectively.

Patients with 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.


13.1 Carcinogenesis, Mutagenesis, and Impairment of Fertility


Long-term studies in animals have not been performed to evaluate carcinogenic potential.


Studies to evaluate the mutagenic potential of glycopyrrolate have not been conducted.

Impairment of Fertility

In reproduction studies in rats, dietary administration of glycopyrrolate resulted in diminished rates of conception in a dose-related manner. Other studies in dogs suggest that this may be due to diminished seminal secretion which is evident at high doses of glycopyrrolate.

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