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Cyproheptadine is an antihistamine of the piperidine type, a first generation H1 receptor antagonist, with serotonin antagonist properties. It is used to relieve symptoms of allergic conditions such as hay fever, urticaria, angioedema, allergic rhinitis, and other allergic reactions. Cyproheptadine is also used to stimulate appetite in patients with anorexia nervosa or cachexia, and to treat serotonin syndrome.
Pharmacology
Pharmacodynamics⁚ Cyproheptadine acts as an antagonist at histamine H1 receptors and serotonin 5-HT2 receptors, and as an inverse agonist at serotonin 5-HT2C receptors. This results in inhibition of histamine and serotonin-mediated effects, such as bronchospasm, vasodilation, and increased capillary permeability.
Mechanism of action
Cyproheptadine's mechanism of action is primarily through its antagonistic effects on histamine H1 receptors and serotonin 5-HT2 receptors, and its inverse agonism at serotonin 5-HT2C receptors. By blocking the actions of histamine and serotonin, cyproheptadine can inhibit a range of physiological responses, including bronchospasm, vasodilation, and increased capillary permeability.
Specifically, cyproheptadine's antagonism at histamine H1 receptors prevents histamine from binding to and activating these receptors, which are found on smooth muscle cells in the airways, blood vessels, and gastrointestinal tract. This results in relaxation of smooth muscle, dilation of blood vessels, and decreased gastric acid secretion.
Cyproheptadine's antagonism at serotonin 5-HT2 receptors blocks the effects of serotonin on these receptors, which are located in the central nervous system, cardiovascular system, and gastrointestinal tract. This results in reduced anxiety, sedation, and inhibition of platelet aggregation.
Additionally, cyproheptadine's inverse agonism at serotonin 5-HT2C receptors causes a conformational change in the receptor that leads to decreased signaling. This results in reduced appetite and weight gain, as well as decreased gastric acid secretion.
Overall, cyproheptadine's diverse pharmacological effects, mediated through its interactions with histamine and serotonin receptors, contribute to its therapeutic efficacy in a variety of conditions.
Pharmacodynamics
Cyproheptadine's pharmacodynamic effects are primarily mediated through its antagonistic actions at histamine H1 receptors and serotonin 5-HT2 receptors, and its inverse agonism at serotonin 5-HT2C receptors.
Histamine H1 receptor antagonism⁚ Cyproheptadine competitively binds to histamine H1 receptors, preventing histamine from binding and activating these receptors. This results in inhibition of histamine-mediated effects, such as⁚
Bronchospasm
Vasodilation
Increased capillary permeability
Pruritus
Wheal and flare reactions
Serotonin 5-HT2 receptor antagonism⁚ Cyproheptadine binds to serotonin 5-HT2 receptors, blocking the effects of serotonin on these receptors. This results in⁚
Reduced anxiety
Sedation
Inhibition of platelet aggregation
Serotonin 5-HT2C receptor inverse agonism⁚ Cyproheptadine acts as an inverse agonist at serotonin 5-HT2C receptors, causing a conformational change in the receptor that leads to decreased signaling. This results in⁚
Reduced appetite
Weight gain
Decreased gastric acid secretion
Overall, cyproheptadine's diverse pharmacodynamic effects contribute to its therapeutic efficacy in a variety of conditions, including allergic reactions, anxiety, and appetite stimulation.
Pharmacokinetics
Absorption⁚ Cyproheptadine is well absorbed from the gastrointestinal tract, with peak plasma concentrations occurring within 2-4 hours after oral administration.
Distribution⁚ Cyproheptadine is widely distributed throughout the body, with high concentrations in the liver, lungs, and kidneys. It is approximately 98% bound to plasma proteins.
Metabolism⁚ Cyproheptadine is extensively metabolized in the liver, primarily by cytochrome P450 enzymes CYP2D6 and CYP3A4. The major metabolites are the desmethyl and didesmethyl derivatives, which are also pharmacologically active.
Excretion⁚ Cyproheptadine and its metabolites are excreted primarily in the urine, with a small amount excreted in the feces. The elimination half-life of cyproheptadine is approximately 8 hours.
Special populations⁚
Hepatic impairment⁚ Cyproheptadine clearance may be reduced in patients with hepatic impairment, leading to increased plasma concentrations and a prolonged elimination half-life.
Renal impairment⁚ Cyproheptadine clearance may be reduced in patients with renal impairment, but the clinical significance of this is unclear.
Pregnancy⁚ Cyproheptadine crosses the placenta, and plasma concentrations in neonates may be similar to those in the mother.
Breastfeeding⁚ Cyproheptadine is excreted in breast milk, and infants exposed to cyproheptadine through breast milk may experience sedation and other adverse effects.
Therapeutic Uses
Cyproheptadine is used to relieve symptoms of allergic conditions such as hay fever, urticaria, angioedema, and allergic rhinitis. It is also used to stimulate appetite in patients with anorexia nervosa or cachexia, and to treat serotonin syndrome.
Allergic conditions
Cyproheptadine is effective in relieving symptoms of various allergic conditions, including⁚
Hay fever (allergic rhinitis)⁚ Cyproheptadine can effectively alleviate symptoms such as sneezing, runny nose, itchy and watery eyes, and nasal congestion.
Urticaria (hives)⁚ Cyproheptadine can reduce the severity and duration of hives, providing relief from itching and discomfort.
Angioedema⁚ Cyproheptadine can help reduce swelling and inflammation associated with angioedema, a condition characterized by sudden swelling of the face, lips, tongue, or other body parts.
Allergic conjunctivitis⁚ Cyproheptadine can relieve symptoms such as itching, redness, and tearing of the eyes caused by allergic conjunctivitis.
Cyproheptadine's antihistaminic and anticholinergic properties contribute to its efficacy in treating allergic conditions. By blocking the actions of histamine and acetylcholine, cyproheptadine reduces inflammation, mucus production, and smooth muscle contraction, providing symptomatic relief.
It is important to note that cyproheptadine is not a cure for allergic conditions, but rather provides symptomatic relief. It is typically used in conjunction with other medications, such as topical corticosteroids or decongestants, for optimal management of allergic symptoms.
Other uses
In addition to its primary use in treating allergic conditions, cyproheptadine has also been found to be effective in managing a variety of other conditions, including⁚
Appetite stimulation⁚ Cyproheptadine can stimulate appetite in patients with anorexia nervosa or cachexia. Its antiserotonergic effects are thought to contribute to this appetite-stimulating effect.
Serotonin syndrome⁚ Cyproheptadine can be used to treat serotonin syndrome, a potentially life-threatening condition caused by excessive serotonin levels. It acts as a serotonin receptor antagonist, helping to reduce serotonin activity and alleviate symptoms such as agitation, confusion, and muscle rigidity.
Migraine prophylaxis⁚ Cyproheptadine has been shown to be effective in preventing migraine headaches. Its antiserotonergic and antihistaminic properties are thought to contribute to its migraine-preventive effects.
Nausea and vomiting⁚ Cyproheptadine's anticholinergic properties may help reduce nausea and vomiting. It is sometimes used in combination with other antiemetics for the management of these symptoms.
Cyproheptadine's versatility and efficacy in treating a wide range of conditions make it a valuable medication in various clinical settings. However, it is important to note that the use of cyproheptadine for conditions other than allergic reactions is considered off-label use, and its safety and effectiveness in these indications may not be as well established.
Contraindications
Cyproheptadine is contraindicated in patients with⁚
Narrow-angle glaucoma⁚ Cyproheptadine's anticholinergic effects can worsen narrow-angle glaucoma by causing pupil dilation and increased intraocular pressure.
Stenosing peptic ulcer⁚ Cyproheptadine's anticholinergic effects can impair gastric motility and exacerbate stenosing peptic ulcers.
Bladder neck obstruction⁚ Cyproheptadine's anticholinergic effects can worsen bladder neck obstruction by reducing bladder muscle tone and impairing urine flow.
Hypersensitivity⁚ Cyproheptadine is contraindicated in patients with known hypersensitivity to the drug or any of its components.
Caution is advised in patients with⁚
Cardiovascular disease⁚ Cyproheptadine's anticholinergic effects can cause tachycardia and hypertension, which may be harmful in patients with underlying cardiovascular conditions.
Hepatic impairment⁚ Cyproheptadine clearance may be reduced in patients with hepatic impairment, leading to increased plasma concentrations and a prolonged elimination half-life.
Renal impairment⁚ Cyproheptadine clearance may be reduced in patients with renal impairment, but the clinical significance of this is unclear.
Pregnancy⁚ Cyproheptadine crosses the placenta, and plasma concentrations in neonates may be similar to those in the mother. Use during pregnancy should be carefully considered and only if the potential benefits outweigh the potential risks.
Breastfeeding⁚ Cyproheptadine is excreted in breast milk, and infants exposed to cyproheptadine through breast milk may experience sedation and other adverse effects. Breastfeeding should be discontinued if cyproheptadine is used.
Dosage and Administration
Cyproheptadine dosage and administration vary depending on the indication and individual patient response. It is typically administered orally, with or without food.
Oral administration
For oral administration, cyproheptadine is available in tablet and syrup formulations. The recommended dosage and frequency of administration vary depending on the indication and individual patient response.
Allergic conditions⁚
Adults and children 12 years and older⁚ 4 mg every 8 hours, not to exceed 16 mg per day.
Children 6 to 11 years⁚ 2 mg every 8 hours, not to exceed 8 mg per day.
Children 2 to 5 years⁚ 1 mg every 8 hours, not to exceed 4 mg per day.
Appetite stimulation⁚
Adults⁚ 4 mg three times daily.
Children 6 to 12 years⁚ 2 mg three times daily.
Children 2 to 5 years⁚ 1 mg three times daily.
Serotonin syndrome⁚
Adults⁚ 4 mg every 6 hours, as needed.
Children⁚ Dosage should be adjusted based on body weight and response.
Cyproheptadine tablets and syrup should be taken with or without food. The tablets should be swallowed whole with a glass of water. The syrup can be diluted in water or juice before administration.
Missed dose⁚ If a dose of cyproheptadine is missed, it should be taken as soon as possible. However, if it is close to the time for the next dose, the missed dose should be skipped and the regular dosing schedule resumed.
Adverse Effects
Cyproheptadine can cause a range of adverse effects, including⁚
Central nervous system effects
Cyproheptadine's anticholinergic and antihistaminic properties can lead to a range of central nervous system effects, including⁚
Sedation⁚ Cyproheptadine's antihistaminic effects can cause drowsiness, particularly at higher doses or in sensitive individuals.
Dizziness⁚ Cyproheptadine's anticholinergic effects can cause dizziness, especially when changing positions or standing up.
Confusion⁚ Cyproheptadine's anticholinergic effects can impair cognitive function and cause confusion, particularly in elderly patients.
Hallucinations⁚ Cyproheptadine's anticholinergic effects can rarely cause hallucinations, especially in children.
Tremor⁚ Cyproheptadine's anticholinergic effects can cause tremor, particularly in elderly patients.
These central nervous system effects are typically dose-dependent and more common in elderly patients and those with underlying neurological conditions.
Anticholinergic effects
Cyproheptadine's anticholinergic properties can lead to a range of adverse effects, including⁚
Dry mouth⁚ Cyproheptadine's anticholinergic effects can inhibit salivary gland secretions, leading to dry mouth.
Blurred vision⁚ Cyproheptadine's anticholinergic effects can paralyze the ciliary muscles of the eye, leading to blurred vision.
Constipation⁚ Cyproheptadine's anticholinergic effects can slow down gastrointestinal motility, leading to constipation.
Urinary retention⁚ Cyproheptadine's anticholinergic effects can relax the bladder muscles, leading to urinary retention.
Tachycardia⁚ Cyproheptadine's anticholinergic effects can block the parasympathetic nervous system, leading to increased heart rate.
These anticholinergic effects are typically dose-dependent and more common in elderly patients and those with underlying autonomic nervous system disorders.
Other effects
In addition to central nervous system and anticholinergic effects, cyproheptadine can cause a range of other adverse effects, including⁚
Weight gain⁚ Cyproheptadine's antiserotonergic effects can increase appetite and lead to weight gain.
Nausea and vomiting⁚ Cyproheptadine's anticholinergic effects can slow down gastrointestinal motility, leading to nausea and vomiting.
Skin reactions⁚ Cyproheptadine can cause skin reactions such as rash, itching, and urticaria.
Blood disorders⁚ Cyproheptadine can rarely cause blood disorders such as thrombocytopenia and agranulocytosis.
Allergic reactions⁚ Cyproheptadine can rarely cause allergic reactions, including anaphylaxis.
These other effects are typically less common and less severe than the central nervous system and anticholinergic effects.
Drug Interactions
Cyproheptadine can interact with a number of other medications, including⁚
CYP2D6 inhibitors
Cyproheptadine is metabolized by the cytochrome P450 enzyme CYP2D6. Drugs that inhibit CYP2D6 can increase cyproheptadine plasma concentrations and prolong its elimination half-life, potentially leading to increased adverse effects.
Examples of CYP2D6 inhibitors include⁚
Antidepressants⁚ Fluoxetine, paroxetine, sertraline
Antipsychotics⁚ Haloperidol, risperidone, thioridazine
Antiarrhythmics⁚ Quinidine, amiodarone
Anticonvulsants⁚ Phenytoin, carbamazepine
Proton pump inhibitors⁚ Omeprazole, lansoprazole
If cyproheptadine is co-administered with a CYP2D6 inhibitor, the dose of cyproheptadine may need to be reduced to avoid excessive adverse effects.
Other drug interactions
In addition to CYP2D6 inhibitors, cyproheptadine can interact with a number of other medications, including⁚
Monoamine oxidase inhibitors (MAOIs)⁚ Cyproheptadine can potentiate the effects of MAOIs, leading to increased risk of serotonin syndrome.
Alcohol⁚ Cyproheptadine can enhance the sedative effects of alcohol.
Anticoagulants⁚ Cyproheptadine may increase the anticoagulant effects of warfarin.
Anticholinergics⁚ Cyproheptadine's anticholinergic effects may be additive with other anticholinergic medications, leading to increased risk of anticholinergic side effects.
Tricyclic antidepressants (TCAs)⁚ Cyproheptadine may increase the anticholinergic and sedative effects of TCAs.
It is important to inform your doctor about all medications you are taking, including prescription drugs, over-the-counter medications, and herbal supplements, to avoid potential drug interactions.
Special Populations
Cyproheptadine use in special populations requires caution and dosage adjustments⁚
Pregnancy and lactation
Pregnancy⁚ Cyproheptadine crosses the placenta, and plasma concentrations in neonates may be similar to those in the mother. The safety of cyproheptadine use during pregnancy has not been established, and it should be used only if the potential benefits outweigh the potential risks to the fetus. Cyproheptadine should be avoided in the first trimester of pregnancy due to the potential for teratogenic effects.
Lactation⁚ Cyproheptadine is excreted in breast milk, and infants exposed to cyproheptadine through breast milk may experience sedation and other adverse effects. Breastfeeding should be discontinued if cyproheptadine is used.
Geriatrics
Elderly patients are more susceptible to the anticholinergic and sedative effects of cyproheptadine. They may experience increased confusion, dizziness, and falls. The starting dose of cyproheptadine should be lower in elderly patients, and it should be increased gradually as tolerated. Close monitoring is recommended to ensure safety and efficacy.
Additionally, elderly patients may have impaired hepatic and renal function, which can affect the metabolism and excretion of cyproheptadine. Dosage adjustments may be necessary to avoid excessive drug accumulation and adverse effects.
Pediatrics
Cyproheptadine is generally safe and effective for use in children. However, the dosage and administration should be adjusted based on the child's age, weight, and individual response.
The starting dose of cyproheptadine for children is typically lower than the adult dose, and it should be increased gradually as tolerated. Close monitoring is recommended to ensure safety and efficacy.
Children may be more susceptible to the anticholinergic and sedative effects of cyproheptadine. They may experience increased drowsiness, dizziness, and behavioral changes. It is important to monitor children closely for these effects and adjust the dosage accordingly.
Overdosage
Cyproheptadine overdosage can cause⁚
Symptoms
Cyproheptadine overdosage can cause a range of symptoms, including⁚
Central nervous system depression⁚ Drowsiness, lethargy, coma
Anticholinergic effects⁚ Dry mouth, blurred vision, urinary retention, tachycardia
Cardiovascular effects⁚ Hypotension, arrhythmias
Respiratory depression⁚ Shallow breathing, respiratory arrest
Seizures
Death (in severe cases)
The severity of symptoms depends on the amount of cyproheptadine ingested and the individual's susceptibility to its effects.
Management
Management of cyproheptadine overdosage involves supportive care and specific measures to address the presenting symptoms⁚
Decontamination⁚ Gastric lavage or activated charcoal may be used to remove unabsorbed cyproheptadine from the gastrointestinal tract.
Supportive care⁚ Vital signs should be monitored closely, and supportive care measures such as oxygen therapy and intravenous fluids may be necessary.
Anticholinergic effects⁚ Anticholinergic symptoms can be treated with physostigmine, a cholinergic agent.
Cardiovascular effects⁚ Hypotension can be treated with vasopressors, and arrhythmias can be treated with antiarrhythmic medications.
Seizures⁚ Seizures can be treated with anticonvulsant medications.
In severe cases, mechanical ventilation or cardiopulmonary resuscitation may be necessary.
Monitoring and Laboratory Tests
Routine monitoring and laboratory tests are not typically necessary during cyproheptadine therapy. However, certain populations or individuals with specific conditions may require closer monitoring⁚
Elderly patients⁚ Elderly patients are more susceptible to the anticholinergic and sedative effects of cyproheptadine. They should be monitored closely for confusion, dizziness, and falls.
Patients with hepatic impairment⁚ Cyproheptadine clearance may be reduced in patients with hepatic impairment, leading to increased plasma concentrations and a prolonged elimination half-life. Liver function tests may be monitored in these patients.
Patients with renal impairment⁚ Cyproheptadine clearance may be reduced in patients with renal impairment, but the clinical significance of this is unclear. Renal function tests may be monitored in these patients.
Pregnancy⁚ Cyproheptadine crosses the placenta, and plasma concentrations in neonates may be similar to those in the mother. Cyproheptadine should be used during pregnancy only if the potential benefits outweigh the potential risks to the fetus.
Breastfeeding⁚ Cyproheptadine is excreted in breast milk, and infants exposed to cyproheptadine through breast milk may experience sedation and other adverse effects. Breastfeeding should be discontinued if cyproheptadine is used.
In addition, patients taking cyproheptadine should be monitored for any signs and symptoms of adverse effects, such as excessive sedation, anticholinergic effects, or allergic reactions.
Dosage Forms
Cyproheptadine is available in the following dosage forms⁚
Tablets
Cyproheptadine tablets are available in strengths of 4 mg and 12 mg. They are typically taken orally, with or without food, every 6 to 8 hours. The dosage and frequency of administration vary depending on the indication and individual patient response.
Allergic conditions⁚
Adults and children 12 years and older⁚ 4 mg every 8 hours, not to exceed 16 mg per day.
Children 6 to 11 years⁚ 2 mg every 8 hours, not to exceed 8 mg per day.
Children 2 to 5 years⁚ 1 mg every 8 hours, not to exceed 4 mg per day.
Appetite stimulation⁚
Adults⁚ 4 mg three times daily.
Children 6 to 12 years⁚ 2 mg three times daily.
Children 2 to 5 years⁚ 1 mg three times daily.
Serotonin syndrome⁚
Adults⁚ 4 mg every 6 hours, as needed.
Children⁚ Dosage should be adjusted based on body weight and response.
Cyproheptadine tablets should be swallowed whole with a glass of water.
Oral syrup
Cyproheptadine oral syrup is available in a strength of 2 mg/mL. It is typically taken orally, with or without food, every 6 to 8 hours. The dosage and frequency of administration vary depending on the indication and individual patient response.
Allergic conditions⁚
Adults and children 12 years and older⁚ 4 mg every 8 hours, not to exceed 16 mg per day.
Children 6 to 11 years⁚ 2 mg every 8 hours, not to exceed 8 mg per day.
Children 2 to 5 years⁚ 1 mg every 8 hours, not to exceed 4 mg per day.
Appetite stimulation⁚
Adults⁚ 4 mg three times daily.
Children 6 to 12 years⁚ 2 mg three times daily.
Children 2 to 5 years⁚ 1 mg three times daily.
Serotonin syndrome⁚
Adults⁚ 4 mg every 6 hours, as needed.
Children⁚ Dosage should be adjusted based on body weight and response;
Cyproheptadine oral syrup can be diluted in water or juice before administration.
Storage and Handling
Cyproheptadine tablets and oral syrup should be stored at room temperature (20-25°C or 68-77°F) in a dry place and protected from light.
Tablets⁚ Cyproheptadine tablets should be stored in their original container to protect them from moisture and light.
Oral syrup⁚ Cyproheptadine oral syrup should be stored in its original container and kept tightly closed to prevent evaporation and contamination.
General handling precautions⁚
Cyproheptadine should be kept out of reach of children.
Do not use cyproheptadine if the expiration date on the package has passed.
Discard any unused cyproheptadine tablets or oral syrup after the expiration date.
Do not share cyproheptadine with others, even if they have the same symptoms.
Proper storage and handling of cyproheptadine will help maintain its stability and effectiveness.
Patient Counseling
Instruct patients on the following when taking cyproheptadine⁚
Importance of compliance
Emphasize to patients the importance of taking cyproheptadine as prescribed, even if they start to feel better. Explain that stopping the medication early can reduce its effectiveness and lead to a recurrence of symptoms.
If a dose is missed, instruct patients to take it as soon as possible. However, if it is close to the time for the next dose, the missed dose should be skipped and the regular dosing schedule resumed.
Advise patients not to take more cyproheptadine than prescribed, as this can increase the risk of adverse effects.
Potential side effects
Inform patients about the potential side effects of cyproheptadine, including⁚
Sedation⁚ Cyproheptadine can cause drowsiness, especially at higher doses or in sensitive individuals.
Dizziness⁚ Cyproheptadine can cause dizziness, especially when changing positions or standing up.
Dry mouth⁚ Cyproheptadine can cause dry mouth due to its anticholinergic effects.
Blurred vision⁚ Cyproheptadine can cause blurred vision due to its anticholinergic effects.
Explain that these side effects are typically mild and transient, but if they become bothersome or persistent, patients should consult their healthcare provider.
Also, advise patients to seek immediate medical attention if they experience any serious side effects, such as⁚
Severe allergic reactions (anaphylaxis)⁚ Hives, swelling of the face, lips, tongue, or throat, difficulty breathing
Hallucinations
Seizures
Lifestyle modifications
In addition to medication, advise patients to make certain lifestyle modifications to improve their condition and reduce the risk of adverse effects from cyproheptadine⁚
Avoid alcohol⁚ Alcohol can enhance the sedative effects of cyproheptadine.
Be cautious when driving or operating machinery⁚ Cyproheptadine can cause drowsiness and dizziness, which can impair reaction time and coordination.
Stay hydrated⁚ Cyproheptadine can cause dry mouth. Encourage patients to drink plenty of fluids to stay hydrated.
Avoid excessive sun exposure⁚ Cyproheptadine can cause photosensitivity, making the skin more sensitive to sunlight. Advise patients to use sunscreen and wear protective clothing when outdoors.
These lifestyle modifications can help patients manage their condition effectively and minimize the potential risks associated with cyproheptadine use.
