Medication Summary
Pharmacologic therapy for ammonia toxicity is directed at hypoxia, bronchospasm, acute lung injury (ALI), hypovolemia, and burns of the skin and eyes. Corticosteroids and antibiotics have limited indications; broader use of these agents in ammonia toxicity is common but controversial.
Beta2 Agonists
Class Summary
These agents produce selective stimulation of beta 2-adrenergic receptors in the bronchial tree and lungs. The resulting relaxation of bronchial smooth muscle relieves bronchospasm and reduces airway resistance.
Albuterol (Proventil HFA, Ventolin HFA, ProAir HFA, AccuNeb, VoSpire ER)
Albuterol (known as salbutamol in Canada and the United Kingdom) is a beta 2-agonist used for the treatment of bronchospasm. This agent relaxes bronchial smooth muscle by its action on beta 2-receptors. It has little effect on cardiac muscle contractility.
Diuretics, Loop
Class Summary
A trial of diuretics can be considered in patients with ammonia toxicity who have evidence of concomitant fluid overload. Diuretics are sometimes considered for the treatment of acute lung injury (ALI), but ventilation with positive end-expiratory pressure (PEEP) may be much more useful than diuretics for optimizing oxygenation because ALI is secondary to alveolar capillary injury, not excess fluid.
Furosemide (Lasix)
Furosemide inhibits sodium chloride reabsorption in the ascending loop of Henle. It should be administered intravenously in patients with ammonia toxicity because this route allows for superior potency and a higher peak concentration, despite an increased incidence of adverse effects, particularly ototoxicity (rare).
Antibiotics, Ophthalmic
Class Summary
For patients with eye exposure to ammonia, ophthalmic antibiotic preparations reduce the risk of infection secondary to tissue injury.
Ciprofloxacin ophthalmic (Ciloxan)
Ciprofloxacin is a fluoroquinolone with activity against pseudomonads, streptococci, methicillin-resistant Staphylococcus aureus (MRSA), Streptococcus epidermidis, and most gram-negative organisms, but no activity against anaerobes. It inhibits bacterial DNA synthesis and growth.
Erythromycin ophthalmic (Ilotycin, Romycin)
This agent is indicated for infections caused by susceptible strains of microorganisms and for prevention of corneal and conjunctival infections.
Neomycin
Neomycin has been an option through the years. However, it is used less frequently, because of the high incidence of sensitivity. Patients with burns to the skin (eg, eyelids) are rarely given prophylactic antibiotics. Neomycin binds to 30S ribosomal subunits, which, in turn, interferes with bacterial protein synthesis.
Cycloplegics/Mydriatics
Class Summary
These agents induce paralysis of accommodation (cycloplegia) by blocking parasympathetic (cholinergic) effects in the eye. This effect is beneficial to prevent ciliary spasm. These agents should be used in consultation with the ophthalmology service.
Cyclopentolate (Cyclogyl)
Cyclopentolate blocks the response of the muscle of the ciliary body and the sphincter muscle of the iris to cholinergic stimulation, thus causing pupillary dilation (mydriasis) and cycloplegia mydriasis and cycloplegia. It induces mydriasis in 30-60 minutes and cycloplegia in 25-75 minutes; these effects last up to 24 hours.
Homatropine (Isopto Homatropine)
Homatropine blocks the response of the sphincter muscle of the iris and the muscle of ciliary body to cholinergic stimulation, producing mydriasis and cycloplegia. It induces mydriasis in 10-30 min and cycloplegia in 30-90 minutes; these effects last up to 48 hours.
Tropicamide (Mydriacyl, Myrdal)
Tropicamide blocks the response of the sphincter muscle of the iris and the muscle of the ciliary body to cholinergic stimulation.
Corticosteroids, Ophthalmic
Class Summary
Corticosteroids decrease the formation of fibroblasts on the cornea and may limit intraocular inflammation. However, these agents may potentiate infection. Ophthalmic corticosteroids should be used in patients with ammonia exposure only in consultation with the ophthalmology service. Also, steroid-antibiotic combinations may be useful.
Prednisolone ophthalmic (Pred Forte, Pred Mild, Omnipred)
Prednisolone decreases inflammation by suppressing migration of polymorphonuclear leukocytes and reversing increased capillary permeability. Note that ophthalmologic steroids are controversial; consult with the ophthalmology service before prescribing.
Fluorometholone (Flarex, FML, FML Forte)
Fluorometholone suppresses migration of polymorphonuclear leukocytes and reverses capillary permeability.
Rimexolone (Vexol)
Rimexolone decreases inflammation by suppressing migration of polymorphonuclear leukocytes and reversing increased capillary permeability.
Anesthetics, Ophthalmic
Class Summary
Ophthalmic anesthetics are used primarily for pain relief. Their duration of action is relatively short-lived, limiting their usefulness outside of the hospital or clinic setting.
Proparacaine ophthalmic (Alcaine, Parcaine)
Proparacaine prevents the initiation and transmission of impulses at the nerve cell membrane by stabilizing and decreasing ion permeability. This agent provides rapid onset of anesthesia, beginning 13-30 seconds after instillation. However, it has a short duration of action (about 15-20 minutes). It is the least irritating of all topical anesthetics.
Corticosteroids
Class Summary
In patients with grade IIb caustic esophageal burns, high doses of methylprednisolone (1 g/1.73 m2/day for 3 days) may reduce stricture development. [19]
Methylprednisolone (A-Methapred, DepoMedrol, Medrol)
Controls or prevents inflammation by controlling rate of protein synthesis, suppressing migration of polymorphonuclear leukocytes (PMNs) and fibroblasts, reversing capillary permeability, and stabilizing lysosomes at cellular level
