The P-I-E-N-O Parkinsn's List Drug Database
cyproheptadine / PeriactinTM
Anti-cholinergic
Description: Cyproheptadine is a piperidine antihistamine. Unlike other antihistamines, this drug also antagonizes serotonin receptors. This action makes cyproheptadine useful in conditions such as vascular headache and anorexia. In a small study, patients with chronic urticaria ranked cyproheptadine higher than five other HA-antagonists in efficacy and freedom from side effects. Cyproheptadine was approved by the FDA in 1961.
Mechanism of Action: Cyproheptadine does not prevent the release of histamine, as do cromolyn and nedocromil, but rather competes with free histamine for binding at HA-receptor sites. Cyproheptadine competitively antagonizes the effects of histamine on HA-receptors in the GI tract, uterus, large blood vessels, and bronchial smooth muscle. Because antihistamines are similar in structure to anticholinergics, local anesthetics, antispasmodics, and ganglionic- and adrenergic-blocking agents, the groups share some properties. Most antihistamines possess significant anticholinergic properties, but cyproheptadine exerts only weak anticholinergic actions. Blockade of central muscarinic receptors appears to account for cyproheptadine's antiemetic effects, although the exact mechanism is unknown. Following prolonged administration of cyproheptadine, tolerance may occur, but this may be beneficial because sedative effects may be reduced.
Cyproheptadine also competes with serotonin at receptor sites in smooth muscle in the intestines and other locations. Antagonism of serotonin on the appetite center of the hypothalamus may account for cyproheptadine's ability to stimulate appetite. Cyproheptadine also has been used to counter vascular headaches, which many believe are caused by changes in serotonin activity. It is unclear how cyproheptadine, a serotonin-receptor antagonist, exerts a beneficial effect on this condition, since sumatriptan, a newer agent specifically indicated for treating migraine, acts as an agonist at serotonin receptors.
Pharmacokinetics: In general, antihistamines are well absorbed from the GI tract, but they vary in solubility, which affects the onset of action. Less soluble antihistamines have a slower onset of action and are less likely to cause toxicity; cyproheptadine has moderate solubility. Peak concentration of cyproheptadine occurs in about 6-9 hours, and the duration of action is about 8 hours. Distribution of cyproheptadine has not been elucidated. Hepatic metabolism of cyproheptadine appears to be extensive, producing a number of metabolites that are conjugated primarily with glucuronic acid or sulfate. Plasma half-life ranges from 1-4 hours. Excretion is mainly renal, with no apparent excretion of unchanged drug. Some unchanged drug and metabolites are excreted in feces.
CONTRAINDICATIONS/PRECAUTIONS: Cyproheptadine is relatively contraindicated in patients with asthma and COPD, especially during acute attacks, because anticholinergic actions can thicken secretions and reduce expectoration.
Cyproheptadine is classified as pregnancy category B. Antihistamines generally are not recommended for use in pregnancy, especially during the third trimester, because there is a risk of seizures in the fetus. Risks-benefits should be considered during pregnancy and in women expecting to become pregnant. Cyproheptadine should be used cautiously in women who are breast-feeding because it can induce hyperexcitability in the infant, seizures in premature infants, and inhibited lactation in the mother. Alternative methods of feeding are recommended if cyproheptadine therapy is deemed necessary.
Cyproheptadine should be used with extreme caution in children. Children can experience paradoxical CNS stimulation and should be supervised in their activities to ensure safety. Some children have experienced respiratory depression and sleep apnea while taking antihistamines; SIDS has occurred. The drug should be used with extreme caution in children with a family history of SIDS or sleep apnea. Antihistamines are contraindicated in neonates because they may experience paradoxical CNS stimulation and there is an increased risk of seizures.
Cyproheptadine should be used with extreme caution in patients predisposed to or with closed-angle glaucoma. Due to its anticholinergic actions, it can increase intraocular pressure, precipitating an acute attack of glaucoma. Cyproheptadine must also be used cautiously in patients with open-angle glaucoma; glaucoma therapy may need to be adjusted.is contraindicated in closed-angle glaucoma.
Cyproheptadine should be used cautiously in patients with hepatic disease. Cyproheptadine is extensively metabolized in the liver, hepatic impairment may lead to a decrease in metabolism, a subsequent increase in drug levels, and an added risk of toxicity.
Because of anticholinergic effects, cyproheptadine should be used with extreme caution in patients with bladder obstruction, GI obstruction, prostatic hypertrophy, or urinary retention.
Antihistamines have a quinidine-like action, so cyproheptadine should be used cautiously in patients with cardiac disease because it can cause tachycardia, palpitations, and/or arrhythmias.
Cyproheptadine should be used with caution in patients with hyperthyroidism or hypertension since it may exacerbate these conditions.
In addition, cyproheptadine should be used with caution in patients undertaking tasks requiring mental alertness. Drowsiness can be severe in some patients. Adverse effects are more likely to occur in geriatric patients. Patients should exercise extreme caution until the effects are known. Alcohol can add to sedation caused by cyproheptadine.
Also, antihistamines can mask signs of allergic reactions, thus delaying the diagnosis of a hypersensitivity reaction.
DRUG INTERACTIONS: If cyproheptadine is used concomitantly with other CNS depressants, additive CNS effects, such as drowsiness and sedation, can occur. Patients taking cyproheptadine should be warned not to self-medicate with with ethanol; barbiturates; anxiolytics, sedatives, and hypnotics; or other HA-blockers.
MAOIs can increase and prolong anticholinergic and CNS depressant effects of cyproheptadine. Their concurrent use is not recommended.
Other drugs that have anticholinergic activity can add to the anticholinergic side effects of cyproheptadine. These drugs include tricyclic antidepressants, direct anticholinergics, and phenothiazines.
Cyproheptadine administered with thyrotropin-releasing hormone, TRH has been found to increase serum amylase and prolactin concentrations.
ADVERSE REACTIONS: CNS depression, manifested as drowsiness, sedation, and/or dizziness, can occur during therapy with cyproheptadine. There is considerable individual patient response to sedative effects, so patients should be warned of the possible impairment of mental acuity. These side effects may disappear after a few days of medication. Geriatric patients may be more disposed to developing adverse CNS depressant effects, and alcohol intake will increase sedation. If symptoms persist or are severe, a dose reduction or change to another antihistamine may be advisable. Other possible CNS effects include headache and hallucinations.
Antihistamines sometimes cause CNS stimulation. This effect is more likely to occur in children with overdoses, and symptoms may include restlessness or akathisia, insomnia, palpitations, and seizures.
Cyproheptadine exerts a small degree of anticholinergic activity. Anticholinergic effects that can occur during therapy include thickening of bronchial secretions, xerostomia, urinary retention, insomnia, nervousness, dysuria, and/or blurred vision. Geriatric patients are more likely to experience such adverse reactions.
Antihistamines can cause adverse GI effects including nausea/vomiting, diarrhea, constipation, and/or abdominal pain. Some of these adverse reactions may be relieved by taking the drug with meals or milk.
Adverse cardiovascular responses are likely to be associated with the anticholinergic properties or the quinidine-like anesthetic effects of antihistamines. These responses may include sinus tachycardia, extrasystoles, palpitations, and/or cardiac arrhythmias. Alpha-adrenergic blockade may lead to hypotension. Hypertension may also occur.
PATIENT INFORMATION:
What do cyproheptadine tablets do?
Cyproheptadine (PeriactinTM ) is an antihistamine. It relieves symptoms of hay fever (seasonal rhinitis), hives (rash or itching), inflammation of the eyes (pink eye, allergic conjunctivitis), and other mild allergic conditions. Generic cyproheptadine tablets are available.
What should my doctor, dentist or pharmacist know before I take cyproheptadine?
They need to know if you have any of these conditions:
How should I take this medicine?
Take cyproheptadine tablets by mouth. Follow the directions on the prescription label. Take cyproheptadine with food or milk if it upsets your stomach. Take your doses at regular intervals. Do not take your medicine more often than directed.
Special precautions for use in children:
Cyproheptadine is not for children under 2 years old; give to older children only as prescribed by the doctor.
What if I miss a dose?
If you miss a dose, take it as soon as you can. If it is almost time for your next dose, take only that dose. Do not take double doses.
What other medicines can interact with cyproheptadine?
Tell your doctor or pharmacist: about all other medicines you are taking, including non-prescription medicines; if you are a frequent user of drinks with caffeine or alcohol; if you smoke; or if you use illegal drugs. These may affect the way your medicine works. Check before stopping or starting any of your medicines.
What side effects may I notice from taking cyproheptadine?
Serious side effects with cyproheptadine include:
Call your doctor as soon as you can if you get any of these side effects.
Minor side effects from cyproheptadine include:
Let your doctor know about these side effects if they do not go away or if they annoy you.
What do I need to watch for while I take cyproheptadine?
Tell your doctor if your symptoms do not improve in 1 or 2 days.
You may get drowsy or dizzy. Do not drive, use machinery, or do anything that needs mental alertness until you know how cyproheptadine affects you. To reduce the risk of dizzy or fainting spells, do not stand or sit up quickly, especially if you are an older patient. Alcohol may increase dizziness and drowsiness. Avoid alcoholic drinks.
Your mouth may get dry. Chewing sugarless gum or sucking hard candy, and drinking plenty of water will help.
Where can I keep my medicine?
Keep out of the reach of children in a container that small children cannot open.
Store at room temperature, or below 40C (104F). Keep container tightly closed. Throw away any unused medicine after the expiration date.
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