Zohydro Er

Uses

Zohydro Er is an opioid agonist used as an analgesic and antitussive agent.

Zohydro Er is indicated for the management of acute pain, sometimes in combination with acetaminophen or ibuprofen, as well as the symptomatic treatment of the common cold and allergic rhinitis in combination with decongestants, antihistamines, and expectorants.

Zohydro Er is also used to associated treatment for these conditions: Cough, Cough caused by Allergic Rhinitis, Cough caused by Common Cold, Nasal Congestion caused by Allergic Rhinitis, Nasal Congestion caused by Common Cold, Pain, Acute, Pain, Chronic, Rhinitis caused by Common Cold, Severe Pain, Moderate Pain, Upper respiratory symptoms caused by Allergic Rhinitis, Upper respiratory symptoms caused by Common Cold

How Zohydro Er works

Zohydro Er binds to the mu opioid receptor (MOR) with the highest affinity followed by the delta opioid receptors (DOR). Zohydro Er's agonist effect at the MOR is considered to contribute the most to its analgesic effects. Both MOR and DOR are Gi/o coupled and and produces its signal through activation of inward rectifier potassium (GIRK) channels, inhibition of voltage gated calcium channel opening, and decreased adenylyl cyclase activity. In the dorsal horn of the spinal cord, activation of pre-synaptic MOR on primary afferents the inhibition of calcium channel opening and increased activity of GIRK channels hyperpolarizes the neuron and prevents release of neurotransmitters. Post-synaptic MOR can also prevent activation of neurons by glutamate through the aforementioned mechanisms.

Zohydro Er can also produce several actions in the brain similarly to other opioids. Activation of MOR in the periaquaductal gray (PAG) inhibits the GABAergic tone on medulo-spinal neurons. This allows these neurons, which project to the dorsal horn of the spinal cord, to suppress pain signalling in secondary afferents by activating inhibitory interneurons. MOR can also inhibit GABAergic neurons in the ventral tegmental area, removing the inhibitory tone on dopaminergic neurons in the nucleus accumbens and contributing to the activation of the brain's reward and addiction pathway. The inhibitory action or MOR likely contributes to respiratory depression, sedation, and suppression of the cough reflex.

Activation of DOR may contribute to analgesia through the above mechanisms but has not been well studied.

Toxicity

Overdosage with hydrocodone presents as opioid intoxication including respiratory depression, somnolence, coma, skeletal muscle flaccidity, cold and clammy skin, constricted pupils, pulmonary edema, bradycardia, hypotension, partial or complete airway obstruction, atypical snoring, and death.

In case of oversdosage the foremost priority is the maintenance of a patent and protected airway with the provision of assisted ventilation if necessary. Supportive measures such as IV fluids, supplemental oxygen, and vasopressors may be used to manage circulatory shock. Advanced life support may be necessary in the case of cardiac arrest or arrhythmias. Opioid antagonists such as naloxone may be used to reverse the respiratory and circulatory effects of hydrocodone. Emergency monitoring is still required after naloxone administration as the opioid effects may reappear. Additionally, if used in an opioid tolerant patient, naloxone may produce opioid withdrawal symptoms.

Food Interaction

• Avoid alcohol. Profound CNS depression, including sedation, respiratory depression, coma, and death may occur.
• Take with or without food. Cmax and AUC are not altered by food in a clinically significant way.

[Major] GENERALLY AVOID: Alcohol may potentiate the central nervous system (CNS) depressant effects of opioid analgesics including hydrocodone.

Concomitant use may result in additive CNS depression and impairment of judgment, thinking, and psychomotor skills.

In more severe cases, hypotension, respiratory depression, profound sedation, coma, or even death may occur.

GENERALLY AVOID: Consumption of alcohol while taking some sustained-release formulations of hydrocodone may cause rapid release of the drug, resulting in high systemic levels of hydrocodone that may be potentially lethal.

Alcohol apparently can disrupt the release mechanism of some sustained-release formulations.

In study subjects, the rate of absorption of hydrocodone from an extended-release formulation was found to be affected by coadministration with 40% alcohol in the fasted state, as demonstrated by an average 2.4-fold (up to 3.9-fold in one subject) increase in hydrocodone peak plasma concentration and a decrease in the time to peak concentration.

Alcohol also increased the extent of absorption by an average of 1.2-fold (up to 1.7-fold in one subject).

GENERALLY AVOID: Grapefruit juice may increase the plasma concentrations of hydrocodone.

The proposed mechanism is inhibition of CYP450 3A4-mediated metabolism of hydrocodone by certain compounds present in grapefruit.

Increased hydrocodone concentrations could conceivably increase or prolong adverse drug effects and may cause potentially fatal respiratory depression.

MANAGEMENT: Patients taking sustained-release formulations of hydrocodone should not consume alcohol or use medications that contain alcohol.

In general, potent narcotics such as hydrocodone should not be combined with alcohol.

Patients should also avoid consumption of grapefruit or grapefruit juice during treatment with hydrocodone.

Zohydro Er Drug Interaction

Major: zolpidem, cyclobenzaprine, pregabalin, alprazolamModerate: diphenhydramine, duloxetine, furosemide, escitalopram, metoprolol, sertraline, cetirizineUnknown: aspirin, omega-3 polyunsaturated fatty acids, atorvastatin, esomeprazole, levothyroxine, acetaminophen, cyanocobalamin, ascorbic acid, cholecalciferol

Zohydro Er Disease Interaction

Major: impaired GI motility, infectious diarrhea, liver disease, prematurity, acute alcohol intoxication, drug dependence, gastrointestinal obstruction, hypotension, intracranial pressure, respiratory depressionModerate: adrenal insufficiency, biliary spasm, hypothyroidism, renal dysfunction, seizure disorders, urinary retention, arrhythmias

Volume of Distribution

The apparent volume of distribution ranges widely in published literature. The official FDA labeling reports a value of 402 L. Pharmacokinetic studies report values from 210-714 L with higher values associated with higher doses or single dose studies and lower values associated with lower doses and multiple dose studies. Zohydro Er has been observed in human breast milk at levels equivalent to 1.6% of the maternal dosage. Only 12 of the 30 women studied had detectable concentrations of hydromorphone at mean levels of 0.3 mcg/kg/day.

Elimination Route

The absolute bioavailability of hydrocodone has not been characterized due to lack of an IV formulation. The liquid formulations of hydrocodone have a Tmax of 0.83-1.33 h. The extended release tablet formulations have a Tmax of 14-16 h. The Cmax remains dose proportional over the range of 2.5-10 mg in liquid formulations and 20-120 mg in extended release formulations. Administration with food increases Cmax by about 27% while Tmax and AUC remain the same. Administration with 40% ethanol has been observed to increase Cmax 2-fold with an approximate 20% increase in AUC with no change in Tmax. 20% alcohol produces no significant effect.

Half Life

The half-life of elimination reported for hydrocodone is 7-9 h.

Clearance

Official FDA labeling reports an apparent clearance of 83 L/h. Pharmacokinetic studies report values ranging from 24.5-58.8 L/h largely dependent on CYP2D6 metabolizer status.

Elimination Route

Most hydrocodone appears to be eliminated via a non-renal route as renal clearance is substantially lower than total apparent clearance. Hepatic metabolism may account for a portion of this, however the slight increase in serum concentration and AUC seen in hepatic impairment indicates a different primary route of elimination.

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