Diphenhydramine chemical structure
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Benadryl

Diphenhydramine hydrochloride (trade name Benadryl®, or Dimedrol outside the US) is an over-the-counter (OTC) antihistamine and sedative. It is also given in conjunction with typical antipsychotics to prevent akathisia. It is a member of the ethanolamine class of antihistaminergic agents. more...

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Diphenhydramine is widely used in nonprescription sleep aids (Nytol, Sominex, Unisom, Compoz, Excedrin PM, etc.) with a 50mg recommended dose mandated by the FDA. In the United Kingdom, Australia, New Zealand, South Africa, and other countries, a 50 to 100mg recommended dose is permitted. In spite of its use and effectiveness as a sleep-inducing agent, when this drug is sold as an antihistamine, warning of the potential loss of alertness is never prominently displayed on packaging, leading to unknown numbers of traffic fatalities.

Unlike true antihistamines, which prevent the release of histamine, 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.

Diphenhydramine is a first generation antihistamine drug. Despite being one of the oldest antihistamines on the market, it is by and large 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. 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. Like many other first generation antihistamines, is also 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, urinary retention, constipation, difficulty concentrating, short-term memory loss, visual disturbances, hallucinations, confusion, and delirium.

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.

Recreational drug users sometimes take several times the recommended dose of diphenhydramine in order to attain an intense hallucinogenic (more accurately, delirious) state. Abusers often call diphenhyramine "The Pink Panther", in reference to the pink colored pills and syrups or they will say they are "drillin" or "Benatrippin" because of the common name brand, Benadryl®. The mental effects are described by many as "dreaming while awake" involving visual and auditory hallucinations which, unlike those experienced with most psychedelics, often cannot be readily distinguished from reality. 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, inhibiting various signal transduction pathways. In the CNS, diphenhydramine readily crosses the blood-brain barrier, exerting effects within the visual and auditory cortex, accounting for reported visual and auditory disturbances. 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 dialation, tachycardia, and dry skin & mucous membranes. Considerable overdosage can lead to myocardial infarction, serious ventricular dysrhythmias, coma and death. Such a side-effect profile is thought to give ethanolamine-class antihistamines a relatively low abuse liability.

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A quick fix: resuscitate your medicine cabinet with these multipurpose essentials
From Men's Fitness, 9/1/04 by Elizabeth M. Ward

Bathroom packed with bottles and tubes of god-knows-what? Instead of trying to organize that medicinal no man's land, just start over. First, grab a trash can and throw away everything you've had for more than six months. Then head to the pharmacy and buy these eight must-haves covering virtually all your home-medicine needs.

PAIN AND SORENESS

Cabinet Member: Motrin

Why: Medications with ibuprofen, such as Motrin, perform triple duty in the body. "Most medications will help to treat pain and inflammation," says William Gouveia, a Tufts University professor of medicine, "but ibuprofen will reduce a fever as well."

COUGHING AND SORE THROAT

Cabinet Member: Robitussin

Why: Buy the DM formula, which packs the dynamic duo of sore-throat drugs: guaifenesin to loosen phlegm and dextromethorphan to suppress coughs. Most other meds contain only one or the other.

CUTS AND SCRATCHES

Cabinet Members: Band-Aid Liquid Bandages and Betadine (povidone iodine)

Why: Betadine decimates just about any germ you can run into when you cut yourself. As for the paint-on Band-Aids, the clear liquid forms a seal over cuts that won't fall off, protecting abrasions while they heal.

CONGESTION

Cabinet Member: Sudafed

Why: These tiny red tablets contain a drug called pseudoephedrine, which helps loosen nasal congestion and relieve stuffy nose. (Nasal sprays only work on the tissue they come into contact with, making them much less effective.)

ITCHING AND RASHES

Cabinet Member: Benadryl Itch-Stopping Cream

Why: This cream contains a drug called diphenhydramine hydrochloride, which eliminates the need to scratch almost anything.

INDIGESTION

Cabinet Member: Mylanta Maximum-Strength Liquid

Why: A swig of Mylanta offers immediate relief from heartburn and indigestion. (Pills are far slower.) And, unlike most medications, Mylanta even works if you're gassy, bursting gas bubbles in your gut and helping to relieve intestinal problems from the inside out.

COLD/CANKER SORES

Cabinet Member: Orajel Medicated Swabs

Why: Instead of spreading gunk on your finger and trying to swirl it around in your pie hole, these benzocaine-packed Q-tips are a better, mess-free option. Just snap the tip of the swab and spread the liquid around the inside of your mouth for immediate relief.

COPYRIGHT 2004 Weider Publications
COPYRIGHT 2004 Gale Group

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