Anticholinergics

What are anticholinergics?

Anticholinergics are drugs that oppose the action of acetylcholine. Acetylcholine is a chemical messenger or neurotransmitter made up of acetic acid and choline. It serves to transmit nervous impulses within the central and peripheral nervous system thereby affecting bodily functions. Anticholinergics have been used for the treatment of certain conditions like urinary incontinence, chronic obstructive pulmonary disease (COPD), hyperactive bladder and some types of poisoning. In Parkinson’s disease where uncontrolled muscle movements occur, anticholinergics are used to prevent these movements. They could sometimes be used prior to surgery to enable body functions to occur when a patient is under an anesthesia.

Examples of anticholinergics

Anticholinergics are prescription-only medicine and not over-the-counter (OTC) drugs. They include:

• Atropine (atropen)
• Belladonna alkaloids
• Clidinium
• Benztropine mesylate (cogentin)
• Dicylomine
• Cyclopentolate (cyclogyl)
• Darifenacin (enablex)
• Fesoterodine (toviaz)
• Flavoxate (urispas)
• Glycopyrollate
• Ipratropium (atrovent)
• Hyoscyamine (levsinex)
• Homatropine hydrobromide
• Orphenadrine
• Oxybutynin (ditropan XL)
• Propantheline (pro-banthine)
• Scopolamine
• Solifenacin (VESIcare)
• Methscopolamine
• Tolterodine (detrol)
• Trihexyphenidyl
• Trospium

Each drug has its specific function and the physician will best prescribe the one suitable for a particular condition. Plants of the deadly nightshade family known as solanaceae serve as a source of some anticholinergics. Mere burning of the roots, stem and seeds of the plant with subsequent inhalation of the smoke has been used for centuries to treat airway obstruction.

Mechanism of action of anticholinergics

As earlier presented, anticholinergics oppose the action of acetylcholine by preventing it’s binding to receptors on nerve endings. They inhibit parasympathetic nerve impulses.

The parasympathetic nerve impulses control involuntary muscle movements in the gastrointestinal tract, lungs, urinary tract, and other body parts by controlling salivation, digestion, micturition, and mucus secretion. When acetylcholine actions are blocked, involuntary muscle movements, digestion, and mucus secretion are reduced resulting in urinary retention and dry mouth.

Uses of anticholinergics

There are a host of uses which include:

• Treatment of chronic obstructive pulmonary disease (COPD)
• Treatment of urinary incontinence and hyperactive bladder
• Treatment of gastrointestinal disorders such as diarrhea
• Asthmatreatment
• Dizziness and motion sickness management
• Treatment of poisoning due to toxins by organophosphate or muscarinic compounds present in insecticides and poisonous mushrooms
• Treatment of symptoms of Parkinson’s disease like the rest tremors

Anticholinergics are sometimes used as muscle relaxants during surgery to help with the anesthesia because they assist in relaxing the patient, normalizing the heartbeat and reducing salivary secretions. They could sometimes be prescribed by a doctor to handle excessive sweating. Glycopyrrolate cream and oxybutynin tablet are typically prescribed for this.

Side effects

Almost every drug has got side effects so it is best to use it properly. Even when used properly, side effects could still occur. Side effects are drug-specific and dose specific. They include:

• Dry mouth or xerostomia
• Blurry vision
• Constipation
• Drowsiness
• Sedation
• Hallucination
• Urinary problems
• Confusion
• Delirium (occurs especially when used in the elderly or following prolonged usage)
• Memory problems
• Reduced salivation
• Reduced sweating

WARNING / INTERACTIONS

Heat exhaustion / heat stroke

Since anticholinergics decrease sweating, it subsequently leads to a rise in temperature. When on any of the anticholinergics, be cautious when exercising- don’t get overheated, avoid hot baths and hot weather. At this stage, one is likely to have heat stroke.

Overdose and alcohol

Taking excessive amounts of an anticholinergic drug can lead to unconsciousness or death. This can also happen when the drugs are taken with alcohol. Overdose usually presents as:

• Dizziness
• Severe drowsiness
• Fever
• Hallucinations
• Confusion
• Difficulty in breathing
• Speech difficulties and clumsiness
• Flushing of skin and warm skin

When an overdose is suspected, a doctor should be seen immediately or report to the emergency room (911). You may use this online tool to report to the American Association of poison Control Centers, or reach out to them by phone through 1-800-222-1222.

Conflicting conditions

As effective as anticholinergics may be, they are unfortunately not suitable for everyone. They are usually not prescribed for the elderly as they are proven to cause confusion, amnesia and exacerbating mental function in those greater than 65years. Also, the American Geriatrics Society has noted that these senior people are much more likely to encounter unwanted side effects than younger people.  Recently, they have been linked with an increasing risk of dementia.

Anticholinergics are also contraindicated in these set of people:

• Myasthenia gravis
• Hyperthyroidism
• Glaucoma
• Hypertension
• Enlarged prostate
• Urinary obstruction
• Increased heart rate
• Heart failure
• Dry mouth when severe
• Hiatus hernia
• Liver disease
• Chronic constipation
• Down’s syndrome

Inform the doctor if you have any of the above-named conditions or if you have a prior history of allergy to anticholinergics.

The way forward

Consult your physician if you feel the drugs may be of help to you. The Doctor is at a good position to decide if the drugs would be beneficial and they also entertain questions about any likely doubts you may be experiencing.