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Medical Disclaimer: This information is for educational purposes only and is not a substitute for professional medical advice.
Brand Name
Prudoxin
Generic Name
Doxepin Hydrochloride
Active Ingredient
DoxepinCategory
Other
Salt Form
Hydrochloride
Variants
1
Different strengths and dosage forms
| Strength | Form | Route | NDC |
|---|---|---|---|
| 50 mg/g | CREAM | TOPICAL | 0378-8130 |
Detailed information about Prudoxin
References used for this content
This page is for informational purposes only and does not replace medical advice. Before using any prescription or over-the-counter medication for Prudoxin, you must consult a qualified healthcare professional.
Doxepin is a tricyclic antidepressant (TCA) used to treat depression, anxiety, and insomnia. It works by affecting neurotransmitters in the brain and acting as a potent antihistamine.
The dosage of Doxepin varies significantly based on the condition being treated. It is imperative to follow the specific schedule provided by your healthcare provider.
Doxepin is generally not recommended for use in children under the age of 12 for the treatment of depression or anxiety. It is not FDA-approved for the treatment of insomnia in pediatric patients. Because tricyclic antidepressants carry a risk of increased suicidal thoughts and behaviors in children and adolescents, healthcare providers exercise extreme caution and typically prefer alternative treatments in this population.
While Doxepin is primarily metabolized by the liver, its metabolites are excreted by the kidneys. No specific dosage adjustment is usually required for mild to moderate renal impairment, but patients with severe kidney disease should be monitored closely for signs of toxicity.
Because Doxepin is extensively metabolized by the liver, patients with hepatic impairment (liver disease) may experience higher drug concentrations in the blood. A lower starting dose and slower titration (increasing the dose gradually) are recommended. For insomnia, a 3 mg dose is preferred over 6 mg in this population.
Geriatric patients are often more sensitive to the anticholinergic and sedative effects of Doxepin. According to the Beers Criteria (guidelines for safe medication use in the elderly), TCAs like Doxepin should generally be avoided for depression in the elderly due to the risk of falls, confusion, and urinary retention. If used for insomnia at the 3 mg dose, patients must be monitored for next-day cognitive impairment.
If you miss a dose, take it as soon as you remember. However, if it is almost time for your next dose, skip the missed dose and return to your regular schedule. Do not double the dose to catch up. If you are taking Doxepin for sleep and you wake up in the middle of the night, do not take a dose unless you have a full 7 to 8 hours remaining for sleep.
A Doxepin overdose is a medical emergency. Symptoms may include extreme drowsiness, dilated pupils, rapid or irregular heartbeat (arrhythmia), low blood pressure, muscle rigidity, vomiting, hallucinations, and seizures. In severe cases, it can lead to coma or cardiac arrest. If an overdose is suspected, contact your local poison control center or seek emergency medical attention immediately.
> Important: Follow your healthcare provider's dosing instructions exactly. Do not adjust your dose or stop taking the medication without medical guidance, as sudden discontinuation can lead to withdrawal symptoms.
Because Doxepin affects multiple receptor systems, side effects are relatively common, particularly when starting the medication or increasing the dose. Many of these are related to its "anticholinergic" properties (blocking the neurotransmitter acetylcholine).
> Warning: Stop taking Doxepin and call your doctor immediately if you experience any of these serious reactions.
Prolonged use of Doxepin may lead to persistent dry mouth, which increases the risk of dental cavities and gum disease. Long-term use of TCAs has also been studied for potential links to cognitive decline in elderly populations, though more research is needed. Additionally, metabolic changes leading to significant weight gain may increase the risk of developing Type 2 diabetes or cardiovascular disease.
Antidepressants and Suicidality: The FDA has issued a Black Box Warning for Doxepin and all other antidepressant medications. Clinical trials have shown that antidepressants increase the risk of suicidal thinking and behavior in children, adolescents, and young adults (ages 18-24) with major depressive disorder and other psychiatric disorders. Anyone considering the use of Doxepin in a child or young adult must balance this risk with the clinical need. Families and caregivers should be advised of the need for close observation and communication with the prescriber. Doxepin is not approved for use in pediatric patients for any indication other than those specifically mentioned in official labeling.
Report any unusual symptoms or changes in mood to your healthcare provider immediately.
Doxepin is a potent medication that requires careful medical supervision. It is not suitable for everyone, and its use must be weighed against potential risks. Patients should be aware that the therapeutic effects of Doxepin for depression may take several weeks to become fully apparent, even though side effects may appear almost immediately.
Full FDA Text Summary: Antidepressants increased the risk compared to placebo of suicidal thinking and behavior (suicidality) in children, adolescents, and young adults in short-term studies of major depressive disorder (MDD) and other psychiatric disorders. Anyone considering the use of Doxepin or any other antidepressant in a child, adolescent, or young adult must balance this risk with the clinical need. Short-term studies did not show an increase in the risk of suicidality with antidepressants compared to placebo in adults beyond age 24; there was a reduction in risk with antidepressants compared to placebo in adults aged 65 and older. Depression and certain other psychiatric disorders are themselves associated with increases in the risk of suicide. Patients of all ages who are started on antidepressant therapy should be monitored appropriately and observed closely for clinical worsening, suicidality, or unusual changes in behavior.
Your healthcare provider may require periodic tests to ensure Doxepin is working safely:
Doxepin significantly impairs mental and physical abilities. It causes marked drowsiness and slowed reaction times. You should not drive, operate heavy machinery, or engage in potentially hazardous activities until you know how Doxepin affects you. This is especially critical during the first few days of treatment or after a dose increase.
Alcohol must be avoided while taking Doxepin. Alcohol increases the sedative effects of the medication, leading to extreme drowsiness, respiratory depression, and an increased risk of accidents. Combining Doxepin with alcohol also increases the risk of a fatal overdose.
Do not stop taking Doxepin abruptly. Sudden discontinuation can lead to a "withdrawal syndrome," which includes symptoms like nausea, headache, malaise (a general feeling of being unwell), irritability, and sleep disturbances. Your doctor will provide a schedule to gradually taper (reduce) your dose over several weeks to minimize these effects.
> Important: Discuss all your medical conditions, including any history of heart, liver, or kidney problems, with your healthcare provider before starting Doxepin.
Doxepin may interfere with certain medical tests, potentially causing false results:
For each major interaction, the mechanism usually involves either the inhibition of liver enzymes (preventing the drug from being broken down) or a pharmacodynamic effect (where two drugs have similar effects that add up to a dangerous level). Management strategies often involve choosing an alternative medication or adjusting the Doxepin dose while monitoring the patient closely.
> Important: Tell your doctor about ALL medications, supplements, and herbal products you are taking, including those purchased without a prescription.
There are several conditions where the risks of Doxepin use clearly outweigh any potential benefits. In these cases, the medication must not be used.
In these situations, a healthcare provider must perform a careful risk-benefit analysis before prescribing Doxepin:
Patients who have had a severe reaction to other tricyclic antidepressants (TCAs) such as Clomipramine, Desipramine, or Nortriptyline are at a high risk of having a similar reaction to Doxepin. This is due to the similar chemical structure shared by all medications in the TCA class. Always inform your doctor if you have had a negative reaction to any psychiatric medication in the past.
> Important: Your healthcare provider will evaluate your complete medical history, including all physical and mental health conditions, before determining if Doxepin is a safe option for you.
Doxepin is classified by the FDA as Pregnancy Category C. This means that animal reproduction studies have shown an adverse effect on the fetus, but there are no adequate and well-controlled studies in humans. Use during pregnancy should only be considered if the potential benefit justifies the potential risk to the fetus.
Trimester-Specific Risks:
Doxepin and its active metabolite, nordoxepin, are excreted into human breast milk. There have been reported cases of apnea (stopping breathing) and excessive drowsiness in infants whose mothers were taking Doxepin. Because of the potential for serious adverse reactions in nursing infants, a decision should be made whether to discontinue nursing or discontinue the drug, taking into account the importance of the drug to the mother.
Doxepin is not FDA-approved for the treatment of insomnia in children. While it is sometimes used for depression in adolescents over the age of 12, it is not recommended for younger children. The primary concern in this population is the increased risk of suicidal ideation and the potential for cardiotoxicity. If prescribed, the child must be under the strict supervision of a pediatric psychiatrist.
The elderly are particularly vulnerable to the side effects of Doxepin.
While the liver does the heavy lifting for metabolism, the kidneys are responsible for clearing the metabolites. In patients with a low Glomerular Filtration Rate (GFR), metabolites can accumulate. Dosage adjustments are not strictly defined by GFR levels, but clinical monitoring for increased side effects is essential. Doxepin is not significantly cleared by hemodialysis.
Patients with cirrhosis or other forms of liver failure (Child-Pugh Class B or C) will have significantly reduced clearance of Doxepin. This leads to higher peak concentrations and a much longer half-life. For these patients, the starting dose should be reduced by at least 50%, and the time between dose increases should be doubled.
> Important: Special populations require individualized medical assessment and frequent follow-up to ensure safety and efficacy.
Doxepin’s pharmacology is multifaceted. Its primary antidepressant action is derived from its ability to inhibit the reuptake of norepinephrine at the presynaptic neuronal membrane. To a lesser extent, it also inhibits serotonin reuptake. This increases the concentration of these monoamines in the synaptic cleft, facilitating neurotransmission.
Its sedative and hypnotic effects are primarily due to its extremely high affinity for H1 histamine receptors. Doxepin is one of the most potent H1 antagonists available, with an affinity that is orders of magnitude higher than its affinity for other receptors. It also acts as an antagonist at muscarinic acetylcholine receptors (causing anticholinergic effects) and alpha-1 adrenergic receptors (causing orthostatic hypotension).
The dose-response relationship for Doxepin is wide. At high doses (75-300 mg), the reuptake inhibition of norepinephrine and serotonin predominates, providing antidepressant effects. At very low doses (3-6 mg), the drug acts almost exclusively as a selective H1 antagonist, which is why it is effective for sleep without the typical TCA side effects. The onset of action for sleep is within 30-60 minutes, while the antidepressant effect usually requires 2 to 4 weeks of consistent dosing.
| Parameter | Value |
|---|---|
| Bioavailability | ~27% (due to extensive first-pass metabolism) |
| Protein Binding | 80% - 90% |
| Half-life | 15 - 31 hours (Parent); 31 - 51 hours (Metabolite) |
| Tmax | 2 - 4 hours |
| Metabolism | Hepatic (CYP2D6, CYP2C19) |
| Excretion | Renal (>90% as metabolites) |
Doxepin is classified as a Tricyclic Antidepressant (TCA). It is related to other TCAs like Amitriptyline, Imipramine, and Clomipramine. Within the TCA class, it is noted for having some of the strongest antihistamine and sedative properties.
Common questions about Prudoxin
Doxepin is a versatile medication primarily used to treat major depressive disorder and various anxiety disorders. It is also FDA-approved at very low doses (3mg and 6mg) specifically for sleep-maintenance insomnia, helping patients stay asleep throughout the night. In some cases, it is used off-label for chronic hives or as a topical cream for itching associated with skin conditions. Because it belongs to the tricyclic antidepressant class, it works by balancing neurotransmitters in the brain. Your doctor will determine the appropriate dose based on whether you are treating a mood disorder or a sleep problem.
The most common side effects of Doxepin include dry mouth, extreme drowsiness, constipation, and blurred vision. These are known as anticholinergic effects and occur because the drug blocks the neurotransmitter acetylcholine. Many patients also report feeling dizzy when standing up quickly, which is caused by a drop in blood pressure. At higher doses used for depression, weight gain and increased appetite are also frequently observed. Most mild side effects tend to decrease as your body adjusts to the medication over several weeks.
No, you should strictly avoid alcohol while taking Doxepin. Both Doxepin and alcohol act as central nervous system depressants, meaning they slow down brain activity. When taken together, they can cause dangerous levels of sedation, respiratory depression, and impaired motor coordination. This combination significantly increases the risk of accidental injury, falls, and fatal overdose. Furthermore, alcohol can worsen the symptoms of depression and anxiety that Doxepin is intended to treat.
Doxepin is generally not recommended during pregnancy unless the potential benefits clearly outweigh the risks to the fetus. It is classified as FDA Category C, meaning animal studies have shown potential harm, but human data is insufficient. Taking Doxepin late in pregnancy may lead to withdrawal symptoms in the newborn, such as breathing problems or tremors. If you are planning to become pregnant or find out you are pregnant while on Doxepin, you must consult your healthcare provider immediately. They will help you weigh the risks of the medication against the risks of untreated depression or insomnia.
The time it takes for Doxepin to work depends on the condition being treated. When used for insomnia, the sedative effect typically begins within 30 to 60 minutes of taking the dose. However, when used for depression or anxiety, it usually takes 2 to 4 weeks of consistent daily use before you notice a significant improvement in your mood. It is important to continue taking the medication as prescribed, even if you do not feel better right away. Do not stop taking it without consulting your doctor, as the full therapeutic benefit takes time to develop.
You should never stop taking Doxepin suddenly, especially if you have been taking it at higher doses for a long period. Abruptly quitting can cause withdrawal symptoms, often referred to as discontinuation syndrome. These symptoms may include nausea, headache, irritability, dizziness, and a return of sleep problems. To stop the medication safely, your doctor will provide a tapering schedule to gradually reduce your dose over several weeks. This allows your brain chemistry to adjust slowly and minimizes uncomfortable side effects.
If you miss a dose of Doxepin, take it as soon as you remember. However, if it is almost time for your next scheduled dose, skip the missed dose and continue with your regular routine. You should never take two doses at once to make up for a missed one. If you are taking the low-dose version for sleep and you miss your bedtime dose, do not take it in the middle of the night unless you have at least 7 to 8 hours left to sleep. Taking it too late can result in severe grogginess the next morning.
Weight gain is a well-documented side effect of Doxepin, particularly when used at the higher doses required for treating depression and anxiety. This occurs because the medication can increase appetite and may also cause metabolic changes that lead to fat storage. At the very low doses used for insomnia (3mg or 6mg), weight gain is much less common but still possible for some individuals. If you are concerned about weight changes, discuss dietary and lifestyle strategies with your healthcare provider. They may also monitor your weight and metabolic health during long-term treatment.
Doxepin has many potential drug interactions, some of which can be very serious. It should never be taken with MAO inhibitors, as this can cause life-threatening reactions. It also interacts with other drugs that cause sleepiness, certain heart medications, and drugs that affect liver enzymes like CYP2D6. Because Doxepin affects so many different receptors, it is vital to provide your doctor and pharmacist with a complete list of all prescriptions, over-the-counter drugs, and herbal supplements you are taking. They will check for interactions and adjust your treatment plan to ensure your safety.
Yes, Doxepin is available as a generic medication in several forms, including capsules and oral solutions. Generic versions are typically much more affordable than brand-name versions like Silenor or Sinequan. The generic capsules are available in multiple strengths ranging from 10mg to 150mg. However, the specific low-dose tablets (3mg and 6mg) used for insomnia may be more expensive or less commonly available as generics in some regions. Always check with your pharmacist to see which version is covered by your insurance plan and is most cost-effective for you.
Other drugs with the same active ingredient (Doxepin)