Acute overdose with hydrocodone is characterized by respiratory depression (a decrease in respiratory rate and/or tidal volume, Cheyne-Stokes respiration, cyanosis), extreme somnolence progressing to stupor or coma, skeletal muscle flaccidity, cold and clammy skin, constricted pupils, and, in some cases, pulmonary edema, bradycardia, partial or complete airway obstruction, atypical snoring, hypotension, circulatory collapse, cardiac arrest, and death.
Hydrocodone may cause miosis, even in total darkness. Pinpoint pupils are a sign of opioid overdose but are not pathognomonic (e.g., pontine lesions of hemorrhagic or ischemic origin may produce similar findings). Marked mydriasis rather than miosis may be seen with hypoxia in overdose situations [see Clinical Pharmacology (12.2) ].
Homatropine has broad, nonspecific anticholinergic / antimuscarinic activity that similar to, although less potent than, atropine. Overdosage of homatropine can cause mydriasis and cycloplegia (fixed and dilated pupils), dry mouth and eyes, decreased sweating, hyperthermia, flushing, headache, visual blurring, gastrointestinal symptoms, constipation, urinary retention, tachycardia and palpitations, anxiety, restlessness, agitation, hallucinations, convulsions, cardiac arrhythmias and coma. Anticholinergic agents can also precipitate acute narrow angle glaucoma.
Treatment of Overdose
Treatment of overdosage is driven by the overall clinical presentation, and consists of discontinuation of Hydrocodone Bitartrate and Homatropine Methylbromide Oral Solution, 5 mg/1.5 mg per 5 mL together with institution of appropriate therapy. Give primary attention to the reestablishment of adequate respiratory exchange through provision of a patent and protected airway and the institution of assisted or controlled ventilation. Employ other supportive measures (including oxygen and vasopressors) in the management of circulatory shock and pulmonary edema as indicated. Cardiac arrest or arrhythmias will require advanced life-support techniques. Gastric emptying may be useful in removing unabsorbed drug.
The opioid antagonists, naloxone and nalmefene, are specific antidotes for respiratory depression resulting from opioid overdose. For clinically significant respiratory or circulatory depression secondary to hydrocodone overdose, administer an opioid antagonist. An antagonist should not be administered in the absence of clinically significant respiratory depression. Because the duration of opioid reversal is expected to be less than the duration of action of hydrocodone in Hydrocodone Bitartrate and Homatropine Methylbromide Oral Solution, 5 mg/1.5 mg per 5 mL, carefully monitor the patient until spontaneous respiration is reliably reestablished. If the response to an opioid antagonist is suboptimal or only brief in nature, administer additional antagonist as directed by the product’s prescribing information.
Hemodialysis is not routinely used to enhance the elimination of hydrocodone from the body.
Physostigmine may be used parenterally for the treatment of the signs and symptoms of homatropine toxicity.
Each spoonful (5 mL) of Hydrocodone Bitartrate and Homatropine Methylbromide Oral Solution, 5 mg/1.5 mg per 5 mL contains 5 mg of hydrocodone bitartrate, USP and 1.5 mg of homatropine methylbromide, USP, for oral administration.
Hydrocodone Bitartrate and Homatropine Methylbromide Oral Solution, 5 mg/1.5 mg per 5 mL also contains the following inactive ingredients: Alcohol (less than 0.1%), Caramel, NF; Cherry Flavor; D&C Red No. 33; Glycerin, USP; Liquid Sugar; Methylparaben, NF; Propylene Glycol, USP; Propylparaben, NF and Sorbitol Solution, USP. Citric Acid, USP or Sodium Citrate, USP may be added for pH adjustment.
The chemical name for hydrocodone is bitartrate is morphinan-6-one, 4,5-epoxy-3-methoxy-17-methyl-, (5α)-, [R-(R*,R*)]- 2,3 dihydroxybutanedioate (1:1), hydrate (2:5). It is also known as 4,5α -Epoxy-3- methoxy-17-methylmorphinan-6-one tartrate (1:1) hydrate (2:5). It occurs as a fine white crystal or crystalline powder, which is derived from the opium alkaloid, thebaine. It has a molecular weight of 494.50 and has the following chemical structure:
The chemical name for homatropine methylbromide is 8-Azoniabicyclo [3.2.1] octane, 3[(hydroxyphenylacetyl)-oxy]-8,8-dimethyl-, bromide,endo-. It occurs as a white crystal or fine white crystalline powder. It has a molecular weight of 370.29 and has the following chemical structure:StructureStructure
12.1 Mechanism of Action
Hydrocodone is an opioid agonist with relative selectivity for the mu-opioid receptor, although it can interact with other opioid receptors at higher doses. The precise mechanism of action of hydrocodone and other opiates is not known; however, hydrocodone is believed to act centrally on the cough center. In excessive doses, hydrocodone will depress respiration.
Homatropine is an anticholinergic that inhibits activity of the muscarinic acetylcholine receptor with less potency than atropine.
Effects on the Central Nervous System
Hydrocodone produces respiratory depression by direct action on brain stem respiratory centers. The respiratory depression involves a reduction in the responsiveness of the brain stem respiratory centers to both increases in carbon dioxide tension and to electrical stimulation.
Hydrocodone causes miosis, even in total darkness. Pinpoint pupils are a sign of opioid overdose but are not pathognomonic (e.g., pontine lesions of hemorrhagic or ischemic origins may produce similar findings). Marked mydriasis rather than miosis may be seen due to hypoxia in overdose situations.
Effects on the Gastrointestinal Tract and Other Smooth Muscle
Hydrocodone causes a reduction in motility associated with an increase in smooth muscle tone in the antrum of the stomach and duodenum. Digestion of food in the small intestine is delayed and propulsive contractions are decreased. Propulsive peristaltic waves in the colon are decreased, while tone may be increased to the point of spasm resulting in constipation. Other opioid-induced effects may include a reduction in biliary and pancreatic secretions, spasm of sphincter of Oddi, and transient elevations in serum amylase.
Effects on the Cardiovascular System
Hydrocodone produces peripheral vasodilation which may result in orthostatic hypotension or syncope. Manifestations of histamine release and/or peripheral vasodilation may include pruritus, flushing, red eyes and sweating and/or orthostatic hypotension.
Effects on the Endocrine System
Opioids inhibit the secretion of adrenocorticotropic hormone (ACTH), cortisol, and luteinizing hormone (LH) in humans [see Adverse Reactions (6) ]. They also stimulate prolactin, growth hormone (GH) secretion, and pancreatic secretion of insulin and glucagon.
Chronic use of opioids may influence the hypothalamic-pituitary-gonadal axis, leading to androgen deficiency that may manifest as low libido, impotence, erectile dysfunction, amenorrhea, or infertility. The causal role of opioids in the clinical syndrome of hypogonadism is unknown because the various medical, physical, lifestyle, and psychological stressors that may influence gonadal hormone levels have not been adequately controlled for in studies conducted to date [see Adverse Reactions (6) ].
Effects on the Immune System
Opioids have been shown to have a variety of effects on components of the immune system in in vitro and animal models. The clinical significance of these findings is unknown. Overall, the effects of opioids appear to be modestly immunosuppressive.
Concentration–Adverse Reaction Relationships
There is a relationship between increasing hydrocodone plasma concentration and increasing frequency of dose-related opioid adverse reactions such as nausea, vomiting, CNS effects, and respiratory depression. In opioid-tolerant patients, the situation may be altered by the development of tolerance to opioid-related adverse reactions.
Homatropine methylbromide has several mild but undesirable clinical properties resulting from its antisecretory effects. These can include: dry mouth, loss of visual accommodation, photophobia, and difficulty in urination. The extent of the above actions is dictated by dose, dose escalation, therefore, results in progressively aversive symptoms in patients.
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