Name of the Cholinergic activators
- Bethanechol
- Pilocarpine
| Bethanechol |
| Availability: Tablets: 5 mg, 10 mg, 25 mg, 50 mg |
| Administration: Give drug on empty stomach 1 hour before or 2 hours after a meal to help prevent nausea and vomiting |
| Postoperative and post-partal urine retention and retention caused by neurogenic atony of bladder TABLETS: Adults. 10 to 50 mg t.i.d. or q.i.d. To determine minimum effective dose: 5 to 10 mg repeated every hr until response is obtained or maximum of 50 mg is reached. Subcutaneous injection: Adults. 2.5 to 5 mg t.i.d. or q.i.d. To determine minimum effective dose: 2.5 mg repeated every 15 to 30 min until response is obtained or maximum of four doses is reached. Minimum effective dose may be repeated t.i.d. or q.i.d., p.r.n. |
Mechanism of Action:
Stimulates parasympathetic nervous system, increasing bladder muscle tone and causing contractions, which initiates urination. Also stimulates gastric motility, increasing gastric tone, and may restore peristalsis. Therapeutic Effect: May initiate urination, bladder emptying. Stimulates gastric, intestinal motility.
Indications:
- Treatment of acute postoperative and postpartum nonobstructive urinary retention
- Neurogenic atony of urinary bladder with retention.
- OFF-LABEL: treatment of gastroesophageal reflux.
Cautions & Contraindications:
- Hypersensitivity to drug
- GI or GU tract obstruction
- Hyperthyroidism
- Active or latent asthma
- Bradycardia
- Hypotension
- Atrioventricular conduction defects
- Coronary artery disease
- Seizure disorders
- Parkinsonism
- Peptic ulcer disease
- Use cautiously in sensitivity to cholinergic or their effects and tartrazine (some products)
- Pregnant or breastfeeding patients & children.
Metabolism and half-life:
Poorly absorbed following PO administration. Does not cross blood-brain barrier. Half-life: Unknown.
Drug Interactions:
- Cholinergic drugs: possibly increased effects of bethanechol
- Ganglionic blockers: possibly severe hypotension, usually first manifested by severe adverse GI reactions
- Procainamide, quinidine: possibly decreased effects of bethanechol.
Side- Effects:
- Headache, malaise
- Hypotension with reflex tachycardia, vasomotor response
- Excessive salivation, lacrimation, miosis
- Abdominal cramps, colicky pain, diarrhea, eructation, nausea, vomiting
- Urinary urgency
- Asthma attack, bronchoconstriction
Nursing Considerations
- Assess urine elimination before starting bethanechol therapy.
- Be aware that patient must have functioned urinary sphincter because a sphincter that doesn’t relax when bladder
- Contracts can push urine upward into renal pelvis and cause reflux infection.
- Give oral bethanechol 1 hour before or 2 hours after meals to reduce risk of nausea and vomiting.
- Don’t give bethanechol I.M. or I.V. because of risk of cholinergic overstimulation, which can cause abdominal cramps, bloody diarrhea, hypotension, shock, or sudden cardiac arrest.
- Always keep atropine nearby during subcutaneous administration.
Patient monitoring/evaluation:
- Monitor blood pressure. Be aware that hypertensive patients may experience sudden blood pressure drop.
- Stay alert for orthostatic hypotension, a common adverse effect.
- Monitor fluid intake and output and residual urine volume.
Patient & Family Teaching
- Tell patient that drug is usually effective within 90 minutes of administration.
- Advise patient to take drug on empty stomach 1 hour before or 2 hours after a meal to avoid GI upset.
- Instruct patient to move slowly when sitting up or standing, to avoid dizziness or light-headedness from blood pressure decrease.
- As appropriate, review all other significant and life-threatening adverse reactions and interactions, especially those related to the drugs, tests, and herbs.
| PILOCARPINE |
| Availability: tablet: 5mg, 7.5mg; ophthalmic solution: 0.4%, 1%,1.25%, 2%, 5% |
| Administration & Handling: ophthalmic solution: for topical use only. Avoid touching dispensing bottle to the eye or to any other surface to prevent eye injury or contamination; contact lens wearers: remove lenses before instillation of drops; wait 10 minutes after dose administration before reinserting contact lenses |
| Radiation-induced Xerostomia: 5 mg PO q8hr; may titrate up to 10 mg PO q8hr; not to exceed 30 mg/day. |
| Xerostomia Associated with SjÖgren’s Syndrome: 5 mg PO q6hr |
| Open angle glaucoma or Ocular hypertension intraocular pressure: 1%,2%, or 4% solution: apply 1-2 drops upto q6h; adjust concentration and frequency as necessary to control IOP. |
| Acute Angle – Closure Glaucoma: prior to pilocarpine ophthalmic, treatment with secretory suppressants and hyperosmotic agents may be needed to lower IOP to <50mmHg and relieve iris ischemia. Initial (1% or 2% solution): Instill 1 drop to affected eyes up to 3 times over 30 minutes. If laser iridoplasty or iridomy is used to break the attack, 1 drop of 4% solution should be administered before procedure. Following Iridoplasty ( 1% solution) : 1 drop to affected eyes QID until an iridotomy can be performed. |
| Postoperative Elevated IOP associated with laser surgery: 1%,2%, or 4% solution: Instill 1-2 drops to eyes 15-60 minutes before surgery. If 2 drops administered, instill 5 minutes apart. |
| Miosis Induction: 1%,2%, or 4% solution: instill 1-2 drops into the eyes. If 2 drops administered, instill 5 minutes apart. |
Mechanism of Action
Cholinergic parasympathomimetic with predominant muscarinic action; increases secretion of exocrine glands (sweat, lacrimal, salivary, intestinal, pancreatic glands, and mucous cells of the respiratory tract may be stimulated
Tone and mobility of gallbladder, biliary duct, and urinary tract may be increased
Indications:
- Radiation-induced Xerostomia
- Xerostomia Associated with SjÖgren’s Syndrome
- Open – angle Glaucoma or ocular hypertension
- Acute angle closure Glaucoma
Cautions & Contraindications:
- Uncontrolled asthma
- Anterior eye inflammation
- Any time miosis in undesirable (eg, narrow-angle glaucoma, acute iritis)
- Hypersensitivity
- Caution in patients with significant cardiovascular disease
Metabolism and Half-life:
Half-Life: 0.76-1.35 hr
Onset: 20 min (initial response for xerostomia)
Drug interactions:
Pilocarpine has serious interactions with the following drugs:
Lonafarnib & Tegafur
Side- Effects:
- Sweating
- Headache
- Flushing
- Dizziness
- Chills
- Eye Irritation
- Nausea
- Urinary frequency
- Rhinitis
- Diaphoresis
- Detached Retina
- Decreased Visual Acuity
Nursing Considerations:
- Remove contact lens before administration.
- Apply light finger pressure on lacrimal sac for 2 minutes after instilling to minimize systemic absorption.
- Since pilocarpine may cause systemic cholinergic effects, the medication may induce bronchospasms or bradycardia. Avoid administering pilocarpine in patients with asthma or bradycardia to avoid worsening symptoms.
- Patients should be advised to exercise caution in night driving and other hazardous occupations in poor illumination.
- In addition, miotics may cause accommodative spasm. Patients should be advised not to drive or use machinery if vision is not clear.
Patient and Family Teaching
- Advise the client to use caution with night driving. Additionally, use of this medication can cause hypotension.
- Do not touch dropper tip to any surface, as this may contaminate the contents.
- Caution is advised with night driving and when hazardous activities are undertaken in poor illumination.
- Pilocarpine hydrochloride ophthalmic solution may cause problems when changing focus between near objects and distant objects. Do not drive or use machinery if vision is not clear.
- Contact lens should be removed prior to the instillation of pilocarpine hydrochloride ophthalmic solution. Wait 10 minutes after dosing before reinserting contact lenses.
- If more than one topical ophthalmic medication is being used, the medicines must be administered at least 5 minutes apart.
- To limit exposure to pilocarpine to the eye alone, close eyes gently and apply pressure with finger to the corner of eye by the nose for 2 minutes after instillation of pilocarpine hydrochloride ophthalmic solution.
- If you sweat a lot, drink enough to replace fluids. Do not get dehydrated. Limit alcoholic beverages.
REFERENCES
- Robert Kizior, Keith Hodgson, Saunders Nursing Drug handbook,1st edition 2024, Elsevier Publications. ISBN-9780443116070
- McGraw Hill- Drug Handbook, Seventh Edition, 2013, McGraw Hill Education Publications,9780071799430.
- April Hazard, Cynthia Sanoski, Davi’s Drug Guide for Nurses -Sixteenth Edition 2019, FA Davis Company Publications,9780803669451.
- Jones and Bartlet, Pharmacology for Nurses, Second Edition, 2020, Jones and Bartlet Learning Publications, ISBN 9781284141986.
- Nursebro.com, Search – Nursebro
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