Antihistamines

Allergies are one of the most common types of acquired health conditions as the causes include various factors. Most of these factors are related to the environment such as dust, pollen, virus and chemicals. Allergic reaction signifies the defense mechanism of the immune system to a foreign particle. Allergic reactions if untreated can lead to bigger complications such as bronchitis and sinusitis. Antihistamines were first synthesized by Daniel Bovet. They play a major role in controlling the release of histamines in the body which are produced as response to an allergen. Histamines are chemicals which are released from the mast cell damage. These chemicals initiate the process of allergic reaction in the blood and tissues which causes discomfort. Histamines have three types of receptors H1, H2 and H3 which are specific for different organ systems. The H1 receptor is associated with vasodilation and smooth muscle stimulation, H2 receptor is associated with the cardiac stimulation and H3 is associated with the feedback inhibition process regulated by the central nervous system.

Types of antihistamines

Antihistamines mainly act upon the receptors of the type of histamine released. Each antihistamine has a tendency to compete in binding to the receptors to inhibit the process of allergic stimulation caused in the organ system. There are two major classes of antihistamines. The first generation and the second generation are classified based on their sedative effect on the patient during the course of their action. The first generation of antihistamines are sedatives as they act upon the parasympathetic nervous system in preventing the release of acetylcholine. Their anticholinergic properties enable them to act fast in providing relief within a few minutes. People who experience motion sickness are often suggested to take antihistamines because it suppresses the ear balance discomfort.

The most common ingredients present in these medications are chlorpheneramine, doxylamine, brompheneramine and dimenhydrinate. Most of these first generation antihistamines are recommended in allergic reactions such as hay fever, viral infection, pollen and dander as they suppress the central nervous system. Patients experience drowsiness for a period of time during the first generation antihistamine treatment.

Second generation antihistamines are not sedative in nature and they have large molecular size and electrostatic nature which makes them noncompeting to cross the blood and brain barrier. The response pertaining to their action is comparatively slow as they do not act upon the central nervous system. Studies have shown the increased administration of non-sedative antihistamines in the recent times. Some of these second generation antihistamines have been banned from the market due to their adverse side effects such as arrhythmia. Most of these antihistamines are prescribed during seasonal allergies.

Side effects of antihistamines

The common side effect of most first generation antihistamines is drowsiness or dizziness. The other side effects include nausea, feeling of dryness in mouth and nostrils and sometimes blurred vision. These happen because of the inhibition of secretions from salivary, nasal and lachrymal glands during the onset of an allergic response. The suppression of central nervous system activity may initiate confusion, disorientation and sometimes hallucination in patients.

Rashes, chest congestion and difficulty in breathing have also been reported as adverse effects of antihistamine administration. In case of H2 receptor antihistamines, diarrhea is significant side effect along with headache. Most of the side effects caused by antihistamine intake subside within a few hours. However increased sensitivity to a certain type of antihistamine has to be immediately reported to the physician.

Anaphylaxis

Anaphylaxis is a hypersensitive reaction due to contact through allergens. These allergens induce an immediate immune response that is life threatening in most occasions. Anaphylactic reactions produce various clinical symptoms such as urticaria, respiratory congestion and gastrointestinal disturbances. Anaphylactic response is caused by certain type of compounds which may include proteins, pollen, venom, hormones and also some food extracts. The immunoglobulin E or IgE is responsible for the onset of anaphylactic reaction when exposed to an allergen.

Mechanism of anaphylactic reaction

A series of reactions take place in the body when anaphylaxis is triggered. The IgE which has a half-life of two days, binds to the fragment crystallizable or FC receptor part of the basophils and mast cells. This process is activated when the person comes in contact with an allergen which in turn mediates cellular de granulation and their release of biogenic amines such as histamine and serotonin. The effects of these biogenic amines may include the smooth muscles which generally constrict at the bronchiolar region and broncho capillary venules. It also causes the arteriole dilation.

Anaphylactic responses are of different types and are associated with allergen sources of different kinds such as pollen, food, insects and also some drugs. It happens because of the antigen contact to which the patient had been previously exposed. This type of antigen is also called an allergen. Systemic anaphylaxis is a serious condition in which the mast cells of the connective tissue become activated resulting in dangerous effects such as airway obstruction, swelling of the epiglottis and ultimately suffocation. Systemic anaphylaxis proceeds into another condition called anaphylactic shock which happens because of suffocation induced by the respective allergen. In addition to these, anaphylaxis may also result because of extreme physical exercise. This condition is also called exercise induced urticaria. Allergies to food like eggs and milk are common among infants. Other than these, underlying conditions such as hay fever, asthma and eczema may also induce anaphylaxis if untreated.

Anaphylactic shock is widely reported in people after consuming foods such as peanuts and Brazil nuts. Such food products induce the anaphylactic reaction in an instant causing severe discomfort and sometimes death. Many people also experience anaphylactic reactions because of penicillin administration. Some reactions of anaphylaxis also include excess production of mucous in the mouth, nose and throat. Atopic patients are highly susceptible to anaphylaxis. Patients having an underlying atopic condition produce high amount of IgE antibodies and hence they must be monitored carefully.

Diagnosis of Anaphylaxis

Anaphylactic reaction is diagnosed based on clinical symptoms such as skin rash (insect bites), hoarse voice, chest congestion, breathing difficulty, diarrhea, vomiting and abdominal cramps. Identification of the source is the predominant factor in the diagnosis of anaphylactic reactions. Thorough examination of the cause with immediate life saving measures must be done. Anaphylaxis can be fatal if not managed properly.

Anaphylaxis Treatment

Avoid foods that induce the condition. In the case of anaphylactic reaction, medical attention must be sought immediately. Oral medications such as Benadryl or diphenhydramine are given. EpiPen or injectable epinephrine is the drug of choice to control the anaphylactic reaction. Intravenous antihistamine drugs and oral steroids are given for a period of time to prevent the reoccurrence of the anaphylactic reactions.

Sedatives

Antihistamines

Antihistamines are widely used for allergies and motion sickness. As they exhibit properties that can indirectly induce drowsiness, there is a class of antihistamines, sold as OTC sleeping pills. However, the American Academy of Sleep Medicine warns that such pills should be used only occasionally. Beware that there is a price to pay for buying OTC antihistamines. Some OTC sedatives combine antihistamines with pain relievers and some combine it with alcohol.

They can induce abnormal muscle spasms. Other side effects are blurred vision, constipation, diarrhea, nausea and vomiting, dry mouth and general dehydration. Therefore she needs to consume plenty of water if she is taking any antihistamine. In elders and children, antihistamines can cause nervousness and insomnia. Similarly, asthmatics should steer clear of antihistamines as these can aggravate their condition. They can affect the behavior of the fetus in the womb. Antihistamines also interfere with lactation. Be warned that OTC antihistamines should never be clubbed with alcohol or other sedatives.

Although it is construed that some antihistamines are non prescription sleep aids, and they are more sedating than prescription hypnotics, beware that their effectiveness may decrease over time. More importantly, OTC sedative is only meant for short-term insomnia and by and large the long term effectiveness and safety of the OTC drugs is questionable. However, for transient insomnia or insomnia based on illness or depression, antihistamines can be an effective OTC tool.

Sedative antihistamine list includes (the following list also contains suggested dosage for an adult. Always take the medications e.m.p (ex modo prescripto as directed by the physician):

• Chlorpheniramine (Chlor-Trimeton) 4 mg every 4 to 6 hrs; maximum dose: 24 mg/day
  
  
• Cyproheptadine (Periactin) , 4 mg at bedtime
  
  
• Clemastine (Tavist), 50-100 mg every 4-6 hours, not to exceed 400 mg/day and it is supplied in table form chewable
  
  
• Diphenhydramine (Benadryl), as a night sleep aid to be taken 30 minutes before bedtime, and the dosage is 50 mg for adults
  
  
• Promethazine (Phenergan) Sedation: 25-50 mg orally or 50 mg rectally
  
  
• Hydroxyzine (Atarax, Vistaril), oral sedation dosage 50-100 mg, IM 25-100 mg. Intravenous (IV), subcutaneous and intra-arterial administrations are not recommended as these can cause thrombosis and digital gangrene.
  
  

These come in various brand and trade names and they can be taken as tablets, syrups or nasal sprays. Droplet form for use in the eyes is also available. The effects of these antihistamines including drowsiness, dizziness, headache, loss of appetite, vision changes, irritability, dry mouth, stomach upset should subside, when the body begins to adjust with the medication. If these side effects continue, it is better to contact the medical practitioner. Sedative antihistamines may be taken with food and milk. Sustained release low acting tablets can be swallowed whole as chewing the sustained release long acting tablets may destroy the action and increase the side effects. Chewable tablets can be chewed thoroughly and swallowed. Suspensions should be shaken before food consumption.

Melatonin

This is a hormone produced by human body – by the pineal gland, a pea-sized structure at the center of the brain. This regulates sleep and wakefulness. Taken as a supplement, melatonin helps to reduce delayed sleep syndrome. This also improves sleep quality and lengthens the period of sleep. Day time alertness also seems to improve when this is taken. Melatonin can treat insomnia without altering the sleep pattern of the individual. It also does not impair any performance related skills.

This may help elders with insomnia as the amount of melatonin produced in the body seems to decrease as one gets older, although it is not recommended for chronic insomnia. Melatonin works on the circadian rhythm – the biological clock that regulates our sleep and wake cycles. Many become melatonin deficient due to age, work schedules and stress. Melatonin supplements are a quick way to adjust the lack of melatonin in the body and rebalance the sleep cycle. These are available OTC and when used in conjunction with herbs like chamomile and lemon balm, help lull the body to sleep acting as a true sedative.

Although Melatonin shows good effects for the treatment of insomnia, if used in excess, this sedative can produce side effects including sexual irregularities, mood swings and depression. Although by and large safe when used in moderation, it is unsafe for small children and pregnant women to use melatonin supplements. It is also not recommended for those with lymphoma, extreme allergies, depression, rheumatoid arthritis, auto immune diseases and for cancer patients. Some melatonin sedatives include:

• clonazepam (Klonopin)
  
  
• lorazepam (Ativan)
  
  
• phenobarbital (Donnatal)
  
  
• zolpidem (Ambien)
  
  

As such Melatonin can cause sleepiness and drowsiness, and if taken with sedatives that cause sleepiness, then too much of sleepiness can result. Research indicates that quick release Melatonin can be more effective than sustained-release formulations, especially when used as sedatives. Intramuscular injections of 20 mg of Melatonin are also available.

SAMe

This is also found naturally in the body. This OTC aid can not only help to sleep but also treats depression and chronic fatigue by promoting serotonin production in the body. Unless consumed in large quantities, SAMe has no known side effects.

Antidepressants used as sedatives

Although the FDA has not approved the use of antidepressants as sedatives, there are those who believe that insomnia is related to depression. As with any other medication for depression, there is a significant risk of suicidal thoughts particularly in adolescents and children. Approximate dosage of antidepressants s.o.s (si opus sit only if there is a need) :

Citalopram 20 mg
Escitalopram 5-10 mg
Fluvoxamine 100 mg
Fluoxetine 20 mg
Paroxetine 20 mg
Sertraline 50-75 mg
Venlafaxine 75 mg
Donormyl sleeping pills are available without prescription and they are approved by the FDA for non-prescription. They are used in the treatment of insomnia. 25 mg of Donormyl is the strongest non-prescription sleeping pill. Possible common side effects of antidepressant sedatives include diarrhea, dizziness, headache, insomnia, rash, vomiting, blurred vision, decreased appetite, cold symptoms, nervousness, cramps, hallucinations, hair loss and decreased coordination.

OTC sedatives side effects

Although OTC sedatives can be effective for an occasional sleepless night, the longer you take them, the less they are likely to make you sleepy. OTC sleep aids can leave you feeling groggy and unwell the next day. This is like the 'hangover' effect. Much remains unknown about the safety and effectiveness of OTC sleep aids.

Dizziness and forgetfulness, clumsiness, feeling off balance, dry mouth and throat are some common side effects. Serious risks of OTC sedatives include severe allergic reaction, facial swelling, memory lapses, hallucinations, suicidal tendencies, sleep-related complexities such as sleep-walking, sleep-driving, and sleep-eating. If any unusual sleep-related behavior is exhibited, consult the doctor immediately.

Over-the-counter sedative tips

• Consult the doctor before taking OTC sedative, although you do not need the doctor concurrence to buy an OTC drug. This is because your doctor can make sure that the sedative does not interfere with other underlying medications.
  
• Certain OTC drugs are not recommended for those with glaucoma, asthma, chronic pulmonary disorders, liver diseases and urinary retention.
  
• Remember that OTC sedatives are only a temporary solution for insomnia and they are not intended to be used for longer than about two weeks.
  
• Persistent insomnia is a symptom of an underlying medical or psychological problem. These cannot be cured with OTC sedatives. It is better to learn about safer and effective way of end sleepless nights.
  
• Never mix alcohol with sedatives and this can increase the sedative effects of the medication.
  
• Combining medications such as OTC sedatives and pain relievers and allergy medicines is very dangerous.
  
• Do not drive or attempt any other activity that may require alertness while taking a sedative.
  
• Over a period of time, you may build up intolerance to sedatives and this can in turn lead to more side effects.
  
• You may also come to rely on sedatives and will be unable to sleep without them.