Insect sting and bite products

• Insect bite and stings are common occurrences. The reaction to these injuries is usually local in nature and confined to limited area of the vicinity of the site injury.however for a group of sensitive indivials, stings from some insects can produce allergic reactions that range from a mild reaction to potentially life-threatening anaphylaxis.

• Complications of insect bite

• Secondary bacterial infection of insect bites can occur if the skin of the affected area is scratched.

• The method of relieving itching should be discouraged because it can abrade the skin ,allowing contamination of the injury with infectious organisms.

• Treatment of insect bites: Nonprescription external analgesics are labeled for use in treating insect bites. However these agents are not effective for scabies.

• Treatment outcomes

• The goal of self- treating insect bites are:

• 1.to relieve the symptoms.

• 2.to prevent secondary bacterial infections

general treatment :

Application of an ice pack may provide sufficient relief of the pain and irritation. If not applying an external analgesic to the site should relieve these symptoms. A skin protection may help prevent secondary bacterial infection of injuries .patients should be advised to avoid scratching the bite.

• Self-treatment of insect bites with a nonprescription product is appropriate if the reaction is confined to the site and if the patient is older than 2 years. Because of possible systemic effects ,a physician should evaluate and treat bites from spiders.

• Non-pharmacologic therapy :

• Non-drug measures include the two methods of preventing insect bite :

• Avoiding insects

• Using repellents

• Use of insect repellents

• Applying insect repellents is useful in preventing insect bites but they are not effective in repelling stinging insects.

• An insect repellent should have an inoffensive odor , protect for several hours ,be effective against as many insects as possible, be relatively safe , withstands all weather conditions.

• Most commercial products contain n,n- diethyl-m-toluamide ,commonly called

• DEET.

• Mechanism of action:

• Repellents are used to protect the skin against insect bite. Even though the exact mechanism of action is not fully known

• Deet like other repellent does not kill insects .the volatile repellent when applied to skin or clothing has vapors that tend to discourage the approach of insects and prevents them from alighting.

• Dosage/administration:

• Repellents which are available in the form of sprays, solutions and creams are applied to the skin as needed. The use of insect repellents on children younger than 2 years should be discouraged. People who are sensitive to these chemicals may deveop skin reactions

• Pharmacologic therapy:

• External analgesics such as local anesthetics ,counterirritants ,topical antihistamine and hydrocortisone are approved for treating the pain and itching of insect bites.

• These agents are not approved for use in children younger than 2 years.

• Calamine ,zinc oxide, and titanium dioxide are useful in preventing secondary bacterial infections. These agents ,however , are not approved for treating the symptoms of insect bites. First-aid antiseptics and antibiotics can also help prevent secondary infections.

• Local anesthetics : • Benzocaine are used widely in topical

preparations for relief of itching and irritation caused by insect bites.

• Other local anesthetics include • Pramoxine • Benzyl alcohol • Lidocaine • Dibucaine • phenol

• Mechanism of action :

• Local anesthetics cause a reversible blockade of conduction of nerve impulses at the site of the application ,thereby producing a loss of sensation.

• Phenol exerts topical anesthetic action by depressing cutaneous sensory receptors.

• Topical antihistamines :

• Diphenhydramine hydrochloride in concentrtionsof 0.5% to2% is the agent used in most products that contain a topical antihistamine.

• Mechanism of action :

• :Exert an anesthetic effect by depressing cutaneous receptors , thereby relieving pain and itching.

• Counterirritants :

• Reduce pain and itching by stimulating cutaneous sensory receptors to provide a feeling of warmth, coolness or milder pain.

• The activity of these agents depends on the concentration. In low concentration they may depress the cutaneous receptors ,resulting in an anesthetic effect. At higher concentrations, they stimulate these receptors.

• Camphor at concentrations of 0.1% to 3% ,camphor depresses cutaneous receptors thereby relieving itching and irritation.

• Menthol in concentrations of less than 1% menthol depresses cutanteous receptors and exerts an analgesic effect.

• Hydrocortisone:

• Topical preparations containing hydrocortisone in concentrations up to 1% for nonprescription use.

• Mechanism of action:

• Topically applied , hydrocortisone is an anti-inflammatory agent capable of preventing or suppressing the development of edema ,swelling and tenderness that accompanies inflammation. Reduction in inflammation results in relief of pain and itching.

• Prolonged administration of hydrocortisone may cause atrophy of the epidermis ,acneiform eruptions, irritation, folliculitis, and cracking of the skin.

• Patients who suffer from scabies , fungal or bacterial infections should be warned against using topical hydrocortisone.

• Patient assessment of insect bite:

• The pharmacist should first find out what type of insect inflicted the injury. A physician should evaluate bites from spiders because of the serious diseases or adverse effects associated with these bites.

• For other insect bite the pharmacist should evaluate the seriousness of the reaction before recommending a nonprescription product.

• If a non allergic reaction is present the pharmacist should recommend the appropriate external analgesic for symptomatic relief.

• The pharmacist should explain to the patient the proper use of the selected product as well as its possible adverse effects.

• If the patient is a child recommendation of a skin protectant to prevent secondary bacterial infection is appropriate.

• Patient counseling for insect bites;

• Counseling for insect bites includes an explanation of how to treat the injury as well as how to prevent future occurrences.

• Asking the patient or caregiver the following questions will help elicit the information needed to accurately assess the cause and seriousness of the injury and to recommend the appropriate treatment.

• 1. Do you know what type of insect bit you?

• . If the cause of the bite is unknown refer the patient to a physician

• 2. have you previously had severe reactions to insect bite ? Is the reaction limited to the site of the bite?

• Refer a patient who has had severe reactions to insect bites to a physician . If the patient has no history of severe reactions and if the present symptoms do not indicate an allergic reaction ,recommend the appropriate treatment.

• 3. what , if anything ,have you used to treat the bite?

• Determine whether the self-treatment was appropriate. If not , recommend appropriate therapy. If the self-treatment was appropriate but ineffective , recommend an alternative treatment.

• 4. have you ever had adverse reactions to topically applied products?