B
Benazepril Hydrochloride
ben-ay′zeh-pril hye-droe-klor′ide
Trade and other names: Lotensin (human preparation) and Fortekor, Benazecare (veterinary preparation)
Functional classification: Vasodilator, angiotensin-converting enzyme (ACE) inhibitor
Pharmacology and Mechanism of Action
ACE inhibitor. Inhibits conversion of angiotensin I to angiotensin II. Angiotensin II is a potent vasoconstrictor and will also stimulate sympathetic stimulation, renal hypertension, and synthesis of aldosterone. The inhibition of aldosterone will decrease sodium and water retention. Benazepril, like other ACE inhibitors, will produce vasodilation and decrease aldosterone-induced congestion. ACE inhibitors also contribute to vasodilation by increasing concentrations of some vasodilating kinins and prostaglandins. Unlike enalapril, benazepril has a dual mode of elimination through the kidneys and liver. Duration of ACE-inhibiting action is 16-24 hours, despite a short plasma half-life, because of high-affinity binding to ACE.
Indications and Clinical Uses
Benazepril, like other ACE inhibitors, is used to treat hypertension and CHF. Evidence shows that it may decrease the likelihood of developing cardiomyopathy in some dogs, but other studies failed to show this benefit. For treatment of occult mitral valve disease in dogs, there has not been a benefit of therapy. It may benefit some cats in heart failure or with systemic hypertension; however, some cats with hypertension may not respond, and ACE inhibitors are not considered a primary treatment for hypertension in cats. Benazepril has limited antihypertensive effects in cats with naturally occurring renal disease but may be effective in slowing the progression of renal failure. In studies in which it has been used in cats with renal insufficiency, it was associated with a small reduction in systemic hypertension, reduced glomerular filtration pressure, decreased glomerular hypertension, reduction in urine protein loss, and an increase in glomerular filtration rate (GFR), but no overall benefits on survival. In dogs it produces similar benefits to animals with renal disease (decreased proteinuria, increased GFR, and lower blood pressure), but it does not increase survival.
Precautionary Information
Adverse Reactions and Side Effects
Benazepril has been well-tolerated in dogs and cats with chronic renal failure. However, benazepril may cause azotemia in some patients; carefully monitor renal parameters after initiation of treatment, particularly in patients receiving high doses of diuretics.
Contraindications and Precautions
Discontinue ACE inhibitors in pregnant animals. ACE inhibitors cross the placenta and have caused fetal malformations and death of the fetus.
Instructions for Use
Dose is based on approved use in dogs in Europe and Canada. Monitor renal function and electrolytes 3-7 days after initiating therapy and periodically thereafter. In studies in cats there was no benefit to doses higher than 0.5-1 mg/kg/day.
Patient Monitoring and Laboratory Tests
Monitor patients carefully to avoid hypotension. With all ACE inhibitors, monitor electrolytes and renal function 3-7 days after initiating therapy and periodically thereafter.
Stability and Storage
Store in a tightly sealed container, protected from light, and at room temperature. Stability of compounded formulations has not been evaluated.
Betamethasone
bay-tah-meth′ah-sone
Trade and other names: Celestone, betamethasone acetate, and betamethasone benzoate
Pharmacology and Mechanism of Action
Potent, long-acting corticosteroid. Anti-inflammatory and immunosuppressive effects are approximately 30 times more than cortisol. Anti-inflammatory effects are complex but primarily occur via inhibition of inflammatory cells and suppression of expression of inflammatory mediators.
Indications and Clinical Uses
Betamethasone is used for treatment of inflammatory and immune-mediated disease. It is used for similar indications as prednisolone and dexamethasone.
Precautionary Information
Adverse Reactions and Side Effects
Side effects from corticosteroids are many and include polyphagia, polydipsia/polyuria, and hypothalamic-pituitary-adrenal (HPA) axis suppression. Adverse effects include GI ulceration, hepatopathy, increased risk of diabetes, hyperlipidemia, decreased thyroid hormone, decreased protein synthesis, delayed wound healing, and immunosuppression. Secondary infections can occur as a result of immunosuppression and include demodex, toxoplasmosis, fungal infections, and UTIs. In horses, additional adverse effects may include risk of laminitis.
Contraindications and Precautions
Use cautiously in patients prone to ulcers or infection or in animals in which wound healing is necessary. Use cautiously in diabetic animals, animals with renal failure, or pregnant animals.
Instructions for Use
Betamethasone is used for similar indications as dexamethasone because of similar potency and duration of effect. Topical forms of betamethasone also are available.
Formulations
Betamethasone is available in 600-mcg (0.6-mg) tablets and 3 mg/mL sodium phosphate injection.
Stability and Storage
Store in a tightly sealed container, protected from light, and at room temperature. Stability of compounded formulations has not been evaluated.
Bethanechol Chloride
Pharmacology and Mechanism of Action
Muscarinic, cholinergic agonist. Parasympathomimetic. Bethanechol stimulates gastric and intestinal motility. It also stimulates contraction of urinary bladder via muscarinic receptor activation. Bethanechol, like other carbamoyl esters, resists hydrolysis by acetylcholinesterase to produce a more sustained response. The onset of action is usually 10 minutes after injection and 30-60 minutes after oral administration. Duration of effect is 4-6 hours.
Indications and Clinical Uses
Bethanechol is used in small animals to increase contraction of urinary bladder. In large animals it may increase gastrointestinal motility, but the efficacy for treating GI stasis problems is questionable.
Precautionary Information
Adverse Reactions and Side Effects
High doses of cholinergic agonists will increase motility of GI tract and cause abdominal discomfort and diarrhea. Bethanechol can cause circulatory depression in sensitive animals.
Instructions for Use
Administer injection SQ only. Doses are derived from extrapolation of human doses or via empiricism. There are no well-controlled efficacy studies available for veterinary species.
Bethanechol is no longer available from commercial sources, but some veterinary compounding pharmacists may be able to supply veterinarians.
Formulations
Bethanechol is available in 5-, 10-, 25-, and 50-mg tablets and 5-mg/mL injection. (Commercial preparations are no longer available but are available through some compounding pharmacies.)
Stability and Storage
Store in a tightly sealed container at room temperature. Compounded oral suspensions prepared from tablets are not stable.
Bisacodyl
Pharmacology and Mechanism of Action
Laxative/cathartic. Bisacodyl acts via local stimulation of GI motility, most likely by irritation of bowel.
Indications and Clinical Uses
Bisacodyl is used as a laxative or for procedures in which bowel evacuation is necessary. It may be used with polyethylene glycol electrolyte solution (e.g., Golytely) to cleanse the bowel prior to endoscopy or surgical procedures.
Precautionary Information
Adverse Reactions and Side Effects
Abdominal discomfort. Fluid and electrolyte loss. Avoid chronic use.
Instructions for Use
Bisacodyl is available as an OTC tablet. Doses are derived from extrapolation of human doses or via empiricism. There are no well-controlled efficacy studies available for veterinary species. Onset of action is approximately 1 hour after administration.
Stability and Storage
Store in a tightly sealed container, protected from light, and at room temperature. Stability of compounded formulations has not been evaluated.
Bismuth Subsalicylate
Pharmacology and Mechanism of Action
Antidiarrheal agent and GI protectant. Precise mechanism of action is unknown, but antiprostaglandin action of salicylate component may be beneficial for enteritis. The bismuth component is efficacious for treating infections caused by spirochete bacteria (Helicobacter pylori gastritis). Bismuth subsalicylate in Pepto-Bismol contains five sources of salicylate, which are absorbed systemically after oral administration. Bismuth subsalicylate also may be found in other antidiarrhea preparations, such as kaolin-pectin formulations (e.g., Kaopectate).
Indications and Clinical Uses
Bismuth subsalicylate is used for symptomatic treatment of diarrhea in small and large animals. Efficacy has not been established for animals. However, in people it has been shown effective for treating or preventing diarrhea caused by enterotoxigenic Escherichia coli (ETEC).
Precautionary Information
Adverse Reactions and Side Effects
Adverse effects are uncommon. Owners should be warned that bismuth will discolor stools black.
Contraindications and Precautions
Salicylate component is absorbed systemically, and overuse should be avoided in animals that cannot tolerate salicylates (such as cats and animals allergic to aspirin).
Instructions for Use
Bismuth subsalicylate is available as an OTC product. Doses are derived from extrapolation of human doses or via empiricism. There are no well-controlled efficacy studies available for veterinary species.
Formulations
Bismuth subsalicylate is available in oral suspension in 262 mg/15 mL or 525 mg/mL in extra-strength formulation and 262-mg tablets. Two tablespoons (30 mL) contain 270-mg salicylate.
Stability and Storage
Store in a tightly sealed container, protected from light, and at room temperature. Stability of compounded formulations has not been evaluated.
Bisoprolol fumarate
Pharmacology and Mechanism of Action
Bisoprolol is a synthetic beta1-selective beta-adrenergic receptor blocker with a low affinity for beta2-receptors in bronchial smooth muscle, blood vessels, and fat cells and no intrinsic sympathomimetic activity. Typical cardioselective effects include lower heart rate, decreased cardiac output, and inhibition of renin release by kidneys. At higher doses it will lose beta1 selectivity and also inhibit some beta2 receptors to affect bronchial and vascular smooth muscle. Clearance in dogs is balanced (60% metabolized by the liver and 40% excreted unchanged), distinguishing bisoprolol from lipophilic beta blockers such as carvedilol and metoprolol and hydrophilic beta blockers like atenolol. In dogs, bisoprolol has high and consistent oral absorption (91%) and a half-life of 4 hours. Although bisoprolol prolongs survival in human patients with heart failure, similar studies have not been conducted in dogs or cats.
Indications and Clinical Uses
Bisoprolol is a beta1 blocker that is somewhat cardioselective and therefore is indicated for conditions that require a reduction in heart rate, heart conductivity, or contractility. Such conditions include tachyarrhythmias and atrial fibrillation. In people it is used to treat hypertension, but this use has not been explored in animals.
Precautionary Information
Adverse Reactions and Side Effects
Beta blockade will result in adverse effects that are attributed to decreased adrenergic tone in the heart. Bradycardia and heart block are possible. At high doses, or in sensitive doses, bisoprolol may produce bronchospasm. Treat bradycardia from overdose with atropine.
Contraindications and Precautions
Use cautiously in animals with airway disease, myocardial failure, and cardiac conduction disturbances. Use cautiously in animals with low cardiac reserve.
Patient Monitoring and Laboratory Tests
Monitor heart rate and rhythm. Monitor blood pressure in patients prone to hypotension.
Stability and Storage
Store in a tightly sealed container, protected from light, and at room temperature. Stability of compounded formulations has not been evaluated.
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