GLYCERIN
| GLYCERIN (gli'ser-in) Fleet Babylax, Glycerol, Osmoglyn GLYCERIN ANHYDROUS Ophthalgan Classifications: fluid and electrolyte agent; hyperosmotic laxative; antiglaucoma; Therapeutic:hyperosmotic laxative; antiglaucoma Pregnancy Category: C |
Availability
50% oral solution; suppositories; 4 mL/applicator, ophthalmic solution
Action
When administered orally, glycerin raises plasma osmotic pressure by withdrawing fluid from extravascular spaces; lowers ocular tension by decreasing volume of intraocular fluid. May also reduce CSF pressure. Topical application to eye reduces edema by hydroscopic effect. Glycerin suppositories apparently work by causing dehydration of exposed tissue, which produces an irritant effect, and by absorbing water from tissues, thus creating more bowel mass. Both actions stimulate peristalsis in the large bowel.
Therapeutic Effect
Reduces intraocular pressure by lowering intraocular fluid. Relieves constipation by absorption of water and stimulation of peristalsis.
Uses
Orally to reduce elevated intraocular pressure (IOP) before or after surgery in patients with acute narrow-angle glaucoma, retinal detachment, or cataract and to reduce elevated CSF pressure. Sterile glycerin (anhydrous) is used topically to reduce superficial corneal edema resulting from trauma, surgery, or disease and to facilitate ophthalmoscopic examination. Used rectally (suppository or enema) to relieve constipation.
Unlabeled Uses
To reduce mortality due to strokes in older adults.
Contraindications
Diabetic ketoacidosis; moderate or severe renal impairment (Clcr <50 mL/min), renal failure; pregnancy (category C); lactation.
Cautious Use
Cardiac disease, mild renal impairment; hepatic disease; diabetes mellitus; thyroid disease; dehydrated or older adult patients.
Route & Dosage
| Decrease IOP Adult/Child: PO 1–1.8 g/kg 1–1.5 h before ocular surgery, may repeat q5h Constipation Adult/Child (≥6 y): PR Insert 1 suppository or 5–15 mL of enema high into rectum and retain for 15 min Child (<6 y): PR Insert 1 infant suppository or 2–5 mL of enema high into rectum and retain for 15 min Neonate: PR 0.5 mL of rectal solution (enema) Reduction of Corneal Edema Adult: Topical 1–2 drops instilled into eye q3–4h |
Administration
Oral- Pour commercially available flavored solution over crushed ice, then sip through a straw. Lemon or lime juice and NS (if allowed) may be added to unflavored solution for palatability.
- Prevent or relieve headache (from cerebral dehydration) by having patient lie down during and after administration of drug.
- Ensure that suppository is inserted beyond rectal sphincter.
Adverse Effects (≥1%)
CNS: Headache, dizziness, disorientation. CV: Irregular heartbeat. GI: Nausea, vomiting, thirst, diarrhea, abdominal cramps, rectal discomfort, hyperemia of rectal mucosa. Metabolic: Hyperglycemia, glycosuria, dehydration, hyperosmolar nonketotic coma.Pharmacokinetics
Absorption: Readily absorbed from GI tract after oral administration; rectal preparations are poorly absorbed. Onset: 10 min PO. Peak: 30 min–2 h. Duration: 4–8 h. Metabolism: 80% metabolized in liver; 10–20% metabolized in kidneys to CO2 and water or utilized in glucose or glycogen synthesis. Elimination: 7–14% excreted unchanged in urine. Half-Life: 30–40 min.Nursing Implications
Assessment & Drug Effects
- Consult physician regarding fluid intake in patients receiving drug for elevated IOP. Although hypotonic fluids will relieve thirst and headache caused by the dehydrating action of glycerin, these fluids may nullify its osmotic effect.
- Monitor glycemic control in diabetics. Drug may cause hyperglycemia (see Appendix F).
Patient & Family Education
- Evacuation usually comes 15–30 min after administration of glycerin rectal suppository or enema.
- Note: Slight hyperglycemia and glycosuria may occur with PO use; adjustment in antidiabetic medication dosage may be required.
Common adverse effects in italic, life-threatening effects underlined; generic names in bold; classifications in SMALL CAPS; 
Canadian drug name; 
Prototype drug