Results for diphenhydramine
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Oncology Encyclopedia:

Diphenhydramine

Key Terms: Allergen, Antihistamine, Extrapyramidal movement disorders.

Definition

Diphenhydramine is an antihistamine used to treat allergies, motion sickness, allergic reactions, insomnia, cough, nausea, and phenothiazine drug-induced abnormal muscle movement.

Purpose

Diphenhydramine is frequently ordered for cancer patients to aid in controlling nausea and itching. It may be given after a blood transfusion to limit allergic reactions to blood products. Because of its sedating properties, diphenhydramine is often used to assist in inducing sleep. It is also used to control nausea, treat the stiffness and tremor of Parkinson's disease, and control symptoms of extrapyramidal neurologic movement disorders (tremors and abnormal involuntary movements of the muscles) caused by some drugs used to treat psychosis or nausea and vomiting). The drug may also be formulated as a syrup and used to relieve a cough caused by minor throat irritation due to a cold or hay fever.

In the context of cancer therapy, diphenhydramine can also be used as a pretreatment to limit the patient's reactions to radiocontrast media or to minimize the toxic side effects of such drugs as docetaxel.

Description

Diphenhydramine is an antihistamine that dries, sedates, and is distributed throughout the body. It is readily absorbed when taken by mouth, with peak action occurring about one hour after ingestion. The effects last from four to six hours. This type of drug seems to compete with histamine for receptor sites after exposure to an allergen. By blocking histamine from attaching to the receptor site, the drug decreases itchiness, a runny nose, hives, and other symptoms of an allergic reaction.

Recommended Dosage

The dose should be adjusted depending on the needs of the patient and their response to the medication. Adults generally take from 25 mg to 50 mg, three to four times daily. For sleep, 50 mg at bedtime is the usual dose. Injectable diphenhydramine, 10 mg to 50 mg, may be administered through a vein or injected deep within a muscle. Some patients may require 100 mg injections. The daily dose should not exceed 400 mg. Patients should not double up on doses if one is missed.

Children weighing more than 20 pounds may take from 12.5 mg to 25 mg, three to four times daily. Children should not consume more than 300 mg in one day. The doctor may calculate a recommended dosage based on the child's weight. Parents should not double up on doses if one is missed.

Lotions or creams with diphenhydramine may be applied to the skin to relieve itching in adults and children older than two. The creams contain 1% or 2% diphenhydramine and may be used on the affected area three to four times per day. Topical diphenhydramine should not be applied to large areas of the body, blistered or oozing skin, sunburn, or lesions caused by poison ivy or chickenpox. Patients should not use topical diphenhydramine with other antihistamine-containing lotions or creams.

Precautions

Patients with angle closure glaucoma, peptic ulcer disease, bowel obstructions, an enlarged prostate, or difficulty urinating due to a blockage in the bladder should not use this medication without a doctor's order and monitoring. This drug should be used with caution in patients with asthma, heart disease, high blood pressure, or an overactive thyroid. Prior to taking this medication, patients with these conditions should discuss this medication with their doctor. Patients should not take diphenhydramine for several days prior to an allergy test. It will interfere with obtaining accurate results.

Elderly patients are especially prone to diphenhydramine's sedating effects. The drug may also cause dizziness and lower blood pressure in this population group. Patients should slowly change position from sitting or lying to standing when taking this medication.

Children also may experience drowsiness. In young children, this drug may produce the opposite effect. Pregnant women and those breast feeding should discuss the use of this and other drugs with their physician prior to use.

Side Effects

Drowsiness commonly occurs after taking diphenhydramine. This effect may be more pronounced if alcohol or another central nervous system depressant, such as a tranquilizer or pain medication, is also ingested. Those taking the drug should refrain from driving or operating machinery or appliances until the medication has worn off. It also may cause dizziness, coordination difficulties, confusion, restlessness, nervousness, difficulty sleeping, blurry or double vision, ringing in the ears, headache, or convulsions.

Stomach distress also is common with diphenhydramine. Patients may develop a poor appetite, nausea, vomiting, diarrhea or constipation. Patients also may experience low blood pressure, palpitations, a rapid or irregular heart beat, an early onset of menstruation, frequent urination, or difficulty urinating, with urine retained in the bladder.

Diphenhydramine may also cause hives, a rash, sensitivity to the sun, and a dry mouth and nose. Thickened lung secretions are common.

A less common but potentially serious side effect of high doses of diphenhydramine is weakening or deterioration of muscle tissue. Patients should be careful not to take higher doses of the drug than their doctor recommends.

Interactions

Alcohol, pain medications, sleeping pills, tranquilizers and antidepressants may make the drowsiness associated with diphenhydramine more severe.

Diphenhydramine's drying effects may be stronger and last longer when taken with an antidepressant called an MAO inhibitor.

Resources

Periodicals

Khosla, U., K. S. Ruel, and D. P. Hunt. "Antihistamine-Induced Rhabdomyolysis." Southern Medical Journal 96 (October 2003): 1023–1026.

Riedl, M. A., and A. M. Casillas. "Adverse Drug Reactions: Types and Treatment Options." American Family Physician 68 (November 1, 2003): 1781–1790.

Vallejo, C. T., M. R. Machiavelli, J. E. Perez, et al. "Docetaxel as Neoadjuvant Chemotherapy in Patients with Advanced Cervical Carcinoma." American Journal of Clinical Oncology 26 (October 2003): 477–482.

Organizations

United States Food and Drug Administration (FDA). 5600 Fishers Lane, Rockville, MD 20857-0001. (888) INFO-FDA (463-6332). .

—Debra Wood, R.N.; Rebecca J. Frey, PhD

 
 
Dental Dictionary: Benadryl

n.pr

Trade name for diphenhydramine hydrochloride, an antihistamine with anticholinergic (drying) and sedative side effects.

 
Drug Info: Diphenhydramine

Brand names: Aler-Dryl®, Aller-Dryl® , Allergia-C®, Allermax®, Altaryl®, Banaril™, Banophen®, Banophen® Elixir, Ben-Tann, Benadryl® , Benadryl® Allergy , Benadryl® Childrens, Benadryl® Childrens Allergy Fastmelt™, Benadryl® Itch Relief , Benadryl® Itch Stopping, Benekraft-25™, Calm-Aid®, Complete Allergy, Compoz® Nighttime Sleep Aid, Dermamycin®, Dermarest® Anti-Itch, Dimine™ 10, Dimine™ 50, Diphedryl®, Diphedryl® Dye Free Allergy, Diphen®, Diphen® AF, Diphen® Cough, Diphenadryl®, Diphenhist®, Diphenhist® Cream, Diphenhist® with Zinc Acetate, Diphenyl®, Diphenylin®, DPH®, Dytan®, Dytan® Chewable, ElixSure® Allergy, Equate® Allergy Medication, Equate® Childrens Allergy Elixir, Genahist®, Hydramine®, Itch Relief®, Nervine®, Night Time™ Sleep-Aid, Nighttime Sleep Aid, Nu-Med®, Nytol® QuickCaps, Pardryl®, PediaCare® Nighttime Cough, Phendry®, Q-Dryl®, Quenalin®, Scot-Tussin® Allergy Relief Formula, Siladryl®, Siladryl® DAS, Silphen® Cough, Simply Sleep™, Sleep II, Sleep Tab® II, Sleep Tabs®, Sleep®, Sleep-ettes®, Sleep-Eze® 3, Sominex®, Somnicaps®, Theraflu® Thin Strips™ Multi Symptom, Total Allergy®, Triaminic® Cough and Runny Nose, Tusstat®, Twilite®, Uni-Hist®, Uni-Tann, Unisom® Sleepgels Maximum Strength, Valu-Dryl®, Wal-dryl, Wal-dryl Anti-Itch, Wal-Som Maximum Strength

Chemical formula:



Diphenhydramine tablets or capsules

What are diphenhydramine tablets or capsules?

DIPHENHYDRAMINE (Banophen®, Benadryl®) is an antihistamine that has many uses. It relieves irritant cough, symptoms of hay fever (allergic rhinitis), hives (rash or itching), and other allergic reactions, motion sickness and vertigo (dizziness and loss of balance), Parkinson's disease, and reduces some side effects associated with the use of antipsychotics. Generic diphenhydramine tablets or capsules are available, with or without a prescription.

What should I tell my health care provider before I take this medicine?

They need to know if you have any of these conditions:
• asthma or chronic obstructive lung disease (COPD)
• glaucoma
• high blood pressure or heart disease
• liver disease
• other chronic illness
• prostate trouble
• pain or difficulty passing urine
• ulcers or other stomach problems
• an unusual or allergic reaction to diphenhydramine, other medicines foods, dyes, or preservatives such as sulfites
• pregnant or trying to get pregnant
• breast-feeding

How should I take this medicine?

Take diphenhydramine tablets or capsules by mouth. Follow the directions on the prescription label. Take diphenhydramine with food or milk if it upsets your stomach. Take your doses at regular intervals. Do not take your medicine more often than directed.

If you are taking diphenhydramine to stop you from getting car (or travel) sick, take the first dose 30 to 60 minutes before you leave.

Contact your pediatrician or health care professional regarding the use of this medicine in children. Special care may be needed.

What drug(s) may interact with diphenhydramine?

• alcohol
• barbiturate medicines for inducing sleep or treating seizures (convulsions)
• doxercalciferol
• medicines for anxiety or sleeping problems, such as diazepam or temazepam
• medicines for hay fever and other allergies
• medicines for mental depression
• medicines for mental problems and psychotic disturbances
• medicines for movement abnormalities as in Parkinson's disease, or for gastrointestinal problems

Tell your prescriber or health care professional about all other medicines you are taking, including non-prescription medicines, nutritional supplements, or herbal products. Also tell your prescriber or health care professional 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 with your health care professional before stopping or starting any of your medicines.

What should I watch for while taking diphenhydramine?

Tell your prescriber or health care professional 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 diphenhydramine 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.

Diphenhydramine may cause dry eyes and blurred vision. If you wear contact lenses you may feel some discomfort. Lubricating drops may help. See your ophthalmologist if the problem does not go away or is severe.

What side effects may I notice from taking diphenhydramine?

Side effects that you should report to your prescriber or health care professional as soon as possible:
• agitation, nervousness, excitability, not able to sleep (these are more likely in children)
• blurred vision
• dizziness or fainting spells
• irregular heartbeat, palpitations, or chest pain
• muscle or facial twitches
• pain or difficulty passing urine
• seizures (convulsions)
Call your prescriber or health care professional as soon as you can if you get any of these.

Side effects that usually do not require medical attention (report to your prescriber or health care professional if they continue or are bothersome):
• drowsiness, dizziness
• dry mouth
• headache
• loss of appetite
• stomach upset, nausea, vomiting, constipation or diarrhea

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, between 15 and 30 degrees C (59 and 86 degrees F). Protect from moisture. Keep container tightly closed. Throw away any unused medicine after the expiration date.

Last updated: 10/22/2003 2:13:00 PM

Important Disclaimer: The drug information provided here is for educational purposes only. It is intended to supplement, not substitute for, the diagnosis, treatment and advice of a medical professional. This drug information does not cover all possible uses, precautions, side effects and interactions. It should not be construed to indicate that this or any drug is safe for you. Consult your medical professional for guidance before using any prescription or over the counter drugs.

 
Veterinary Dictionary: diphenhydramine

An antihistamine used as the hydrochloride in treatment of allergic disorders and also for its sedative, antiemetic, antitussive, local anesthetic, and anticholinergic effects. Well known as Benadryl.

 
Wikipedia: diphenhydramine
Diphenhydramine_Structure.svg
Diphenhydramine
Systematic (IUPAC) name
2-benzhydryloxy-N,N-dimethyl-ethanamine
Identifiers
CAS number 58-73-1
ATC code D04AA32 D04AA33, R06AA02
PubChem 3100
DrugBank APRD00587
Chemical data
Formula C17H21NO 
Mol. mass 255.355 g/mol
Pharmacokinetic data
Bioavailability 86% bound to plasma protein
Protein binding 98 to 99%
Metabolism Various cytochrome P450 liver enzymes (cyp 2D6 (80%) ,cyp 3A4 (10%)
Half life 2-8 hours
Excretion 94% through the urine, 6% through feces
Therapeutic considerations
Pregnancy cat.

B
Legal status

Over-the-counter, non-regulated
Routes Oral, parenteral (IM), suppository
Indicated for:

Other uses:
Contraindications:
  • Use in neonates and premature infants
  • Use in nursing mothers
  • Use as a local anesthetic
  • Use in people with hypersensitivity to diphenhydramine hydrochloride and other antihistamines of similar chemical structure
Non-medical use/abuse:
  • Used as a deliriant/hallucinogen
Side effects:

Severe:

Atypical sensations:

  • Feelings of heaviness, hearing disturbance

Cardiovascular:

  • Hypertension in sensitive individuals

Ear, nose, and throat:

  • Dryness of the nose and throat, heartburn

Endocrinal:

  • Increased or decreased appetite

Eye:

  • Dryness of the eyes, redness of the eyes, yellowing of the eyes

Gastrointestinal:

  • Constipation, nausea

Hematological:

  • Hepatotoxicity in extremely large dosages

Musculoskeletal:

  • Incoordination, slow muscle response, fasciculations (twitching), restlessness, extrapyramidal side-effects, restless-leg syndrome

Neurological:

  • Confusion, clouded thinking, drowsiness, hallucinations, delirium, euphoria, short-term memory loss

Psychological:

  • Agitation, anxiety, emotional lability, depression, excitability (especially in children), paranoia

Respiratory:

  • Decreased respiration

Skin:

Urogenital and reproductive:

  • Urinary retention, sexual dysfunction, vaginal dryness, decreased libido

Miscellaneous:

  • ?

Diphenhydramine hydrochloride (trade name Benadryl, as produced by J&J, or Dimedrol outside the U.S. & Canada. Nytol as a sleeping pill) is an over-the-counter (OTC) antihistamine, sedative and hypnotic. It may also be used for the treatment of extrapyramidal side effects of typical antipsychotics. It is a member of the ethanolamine class of antihistaminergic agents.

Diphenhydramine was the first known antihistamine, invented in 1943 by Dr. George Rieveschl.

The brand Benadryl is currently trademarked in the United States by Pfizer, however many drug store chains and retail outlets manufacture less-costly generic versions under their own store brands.

Pharmacological action

Diphenhydramine works by blocking the effect of histamine at H1 receptor sites. This results in effects such as the reduction of smooth muscle contraction, making diphenhydramine a popular choice for treatment of the symptoms of allergic rhinitis, hives, motion sickness, and insect bites and stings.

In the 1960s it was found that diphenhydramine inhibits reuptake of the neurotransmitter serotonin. This discovery led to a search for viable antidepressants with similar structures and fewer side effects, culminating in the invention of fluoxetine (Prozac), a selective serotonin reuptake inhibitor (SSRI). A similar search had previously led to the synthesis of the first SSRI zimelidine from chlorpheniramine, also an antihistamine.

Common use and dosage

Diphenhydramine is a first-generation antihistamine drug. Despite being one of the oldest antihistamines on the market, it is largely the most effective antihistamine available either by prescription or over-the-counter, and has been shown to exceed the effectiveness of even the latest prescription drugs.[1] Consequently, it is frequently used when an allergic reaction requires fast, effective reversal of the often dangerous effects of a massive histamine release. However, it is not always the drug of choice for treating allergies.

It is known that diphenhydramine has sedative properties. Many new antihistamines have been introduced without the side effect of sedation. The drug is also used as a sleep aid and is an ingredient in many sleep aids, such as Unisom gelcaps (however, the tablet form of Unisom contains Doxylamine, a different active ingredient[2]), and most notably Tylenol PM where it is combined with Acetaminophen (Paracetamol), and Nytol and Sominex which have diphenhydramine as the only active ingredient. Several generic and store brands of antihistamines and sleep aids also contain solely diphenhydramine.

Diphenhydramine is widely used in nonprescription sleep aids with a maximum recommended dose of 50mg (as the hydrochloride salt) being mandated by the FDA. In the United Kingdom, Australia, New Zealand, South Africa, and other countries, a 50 to 100mg recommended dose is permitted.

There are also topical formulations of diphenhydramine available, including creams, lotions, gels, and sprays. They are used to relieve itching, and have the advantage of causing much less systemic effect (i.e. drowsiness) than oral forms.

Side effects

Like many other first generation antihistamines, diphenhydramine is a potent anticholinergic agent. This leads to profound drowsiness as a very common side-effect, along with the possibilities of motor impairment (ataxia), dry mouth and throat, flushed skin, rapid or irregular heartbeat (tachycardia), blurred vision at nearpoint due to lack of accommodation (cycloplegia), abnormal sensitivity to bright light (photophobia), pupil dilatation (mydriasis), urinary retention (ischuria), constipation, difficulty concentrating, short-term memory loss, visual disturbances, hallucinations, confusion, erectile dysfunction, and delirium. Some side effects such as twitching may be delayed until the drowsiness begins to cease and the person is in more of an awakening mode. Diphenhydramine also has local anesthetic properties, and has been used for patients allergic to common local anesthetics like lidocaine.[3] Severe, prolonged twitching and muscle spasm have also been experienced.

The most common cardiac dysrhythmias associated with diphenhydramine overdose are sinus bradycardia, elongated S-T segment interval, and premature ventricular contraction.

Diphenhydramine is very similar in its effects to dimenhydrinate (Dramamine®), its 8-chlorotheophylline salt, although the latter is approximately 60% the potency in terms of required dosage and is slightly less sedating.

Some patients have an allergic reaction to diphenhydramine in the form of hives.[citation needed]

Recreational use

Those who use diphenhydramine recreationally take a higher dose than recommended (usually between 225mg and 450mg)[4] for its deliriant effects. Diphenhydramine is also a component of the recreational form of heroin known as "cheese" or "chiva". The mental effects are described by many as "dreaming while awake" involving visual and auditory hallucinations which, unlike those experienced with most psychedelic drugs, often cannot be readily distinguished from reality. Diphenhydramine generally has a low abuse profile due to the frequently unpleasant nature of the hallucinations. People who consume a high recreational dose can possibly find themselves in a hallucination which places them in a familiar situation with people and friends and rooms they know, while in reality being in a totally different setting. Inexperienced users of hallucinogens are liable to panic. Many users report a side effect profile consistent with tropane glycoalkaloidal poisoning. This is due to antagonism of muscarinic acetylcholine receptors in both the central and autonomic nervous system which inhibits various signal transduction pathways. In the CNS, diphenhydramine readily crosses the blood-brain barrier, exerting effects within the visual and auditory cortex.

Other CNS effects occur within the limbic system and hippocampus, causing confusion and temporary amnesia. Toxicology also manifests in the autonomic nervous system, primarily at the neuromuscular junction, resulting in ataxia and extrapyramidal side-effects, and at sympathetic post-ganglionic junctions, causing urinary retention, pupil dilation, tachycardia, irregular urination, and dry skin and mucous membranes. Considerable overdosage can lead to myocardial infarction (heart attack), serious ventricular dysrhythmias, coma and death. Such a side-effect profile is thought to give ethanolamine-class antihistamines a relatively low abuse liability. The specific antidote for diphenhydramine poisoning is physostigmine, usually given by IV in hospital.

See also

External links

References

Notes

  1. ^ Raphael GD, Angello JT, Wu MM, Druce HM (2006). "Efficacy of diphenhydramine vs desloratadine and placebo in patients with moderate-to-severe seasonal allergic rhinitis.". Ann Allergy Asthma Immunol 96 (4): 606-614. PMID 16680933. 
  2. ^ Chattem: Unisom.
  3. ^ http://www.postgradmed.com/issues/1999/08_99/smith.htm
  4. ^ http://www.erowid.org/pharms/diphenhydramine/diphenhydramine_dose.shtml

Sources

Antihistamines (primarily R06)
Aminoalkyl ethers Bromazine • Carbinoxamine • Clemastine • Chlorphenoxamine • Diphenylpyraline • Diphenhydramine • Doxylamine
Substituted alkylamines Brompheniramine • Chlorphenamine • Dexbrompheniramine • Dexchlorpheniramine • Dimetindene • Pheniramine • Talastine
Substituted ethylenediamines Chloropyramine • Histapyrrodine • Mepyramine • Methapyrilene • Tripelennamine (Pyribenzamine)
Phenothiazine derivatives Alimemazine • Hydroxyethylpromethazine • Isothipendyl • Mequitazine • Methdilazine • Oxomemazine • Promethazine
Piperazine derivatives Buclizine • Cetirizine • Chlorcyclizine • Cinnarizine • Cyclizine • Hydroxyzine • Levocetirizine • Meclizine • Niaprazine • Oxatomide
Others for systemic use Antazoline • Azatadine • Bamipine • Cyproheptadine • Deptropine • Dimebon • Ebastine • Epinastine • Ketotifen • Mebhydrolin • Mizolastine • Phenindamine • Pimethixene • Pyrrobutamine • Rupatadine • Triprolidine • selective (Acrivastine • Astemizole • Azelastine • Desloratadine • Fexofenadine • Loratadine • Terfenadine)
For topical use Bamipine • Chloropyramine • Chlorphenoxamine • Clemastine • Dimetindene • Diphenhydramine • Isothipendyl • Mepyramine • Promethazine • Thenalidine
Antiallergic agents excluding corticosteroids Antazoline • Azelastine
Other antiallergics Emedastine • Epinastine • Ketotifen • Olopatadine
Antipruritics (D04)
Antihistamines for topical use Thonzylamine - Mepyramine - Thenalidine - Tripelennamine - Chloropyramine - Promethazine - Tolpropamine - Dimetindene - Clemastine - Bamipine - Isothipendyl - Diphenhydramine - Chlorphenoxamine
Anesthetics for topical use Lidocaine - Cinchocaine - Oxybuprocaine - Benzocaine - Quinisocaine - Tetracaine - Pramocaine
Deliriants (anticholinergic hallucinogens)
3-quinuclidinyl benzilate, Atropine, Dimenhydrinate, Diphenhydramine, Hyoscyamine, Scopolamine, Cyclizine

This entry is from Wikipedia, the leading user-contributed encyclopedia. It may not have been reviewed by professional editors (see full disclaimer)

 
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Oncology Encyclopedia. Gale Encyclopedia of Cancer. Copyright © 2006 by The Gale Group, Inc. All rights reserved.  Read more
Dental Dictionary. Mosby's Dental Dictionary. Copyright © 2004 by Elsevier, Inc. All rights reserved.  Read more
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Veterinary Dictionary. Saunders Comprehensive Veterinary Dictionary 3rd Edition. Copyright © 2007 by D.C. Blood, V.P. Studdert and C.C. Gay, Elsevier. All rights reserved.  Read more
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