Antihistamines topical

There is still debate whether oral antihistamines control ocular allergy as well as topical antihistamines. Topical antihistamines are recommended before oral agent in step therapy because of the increased risk of systemic side effects with oral drugs. Additionally, topical antihistamines provide faster relief of ocular symptoms. Consider oral antihistamines... 

Acetaminophen or a nonsteroidal antiinflammatory agent, such as ibu-profen, can be used to relieve pain and malaise in acute otitis media. Decongestants, antihistamines, topical corticosteroids, or expectorants have not been proven effective for acute otitis media. 

In case of an obstruction of the nasal airways, the swelling should first be reduced and then the patient should apply the anti-inflammatory medication to ensure its necessary distribution over the complete mucosa. Antihistamines in addition to oral therapy may also be applied locally, intranasally or conjunctivally. The combination of all three substance groups (H, antihistamines, topic glucocorticoids and antileukotrienes) as a pretreatment as well as a symptomatic treatment during immunotherapy increases the chances of success of hyposensitization in our experience [unpubl. data]. 

Proven therapeutic modalities include avoidance of allergens and pharmacologic management with antihistamines, topical and systemic decongestants, topical steroids, cromolyn sodium, and immunotherapy. 

Sharif NA, Hellberg MR, Yanni JM. Antihistamines, topical ocular. In Wolff ME, ed. Burger s Medicinal Chemistry and Drug Discovery. 5th Ed. New York John Wiley Sons,... 

Topical Application. Azelastine (11) and levocabastine (13) have been developed for topical appHcation (45). The topical antihistamines address the preference of some patients for a local treatment and allow adrninistration of dmg directly to the site requited. The advantage of this therapeutic approach is likely to be in the speed of onset of symptom rehef. In contrast to earlier reports of sensitization with older antihistamines locally apphed to the skin (46), sensitization has not been reported with local appHcation to the nose or eyes. 

The principal OTC pharmaceutical products include cold remedies, vitamins and mineral preparations, antacids, analgesics, topical antibiotics, antiftingals and antiseptics, and laxatives. Others include suntan products, ophthalmic solutions, hemorrhoidal products, sleep aids, and dermatological products for treatment of acne, dandmff, insect parasites, bums, dry skin, warts, and foot care products (11). More recent prescription-to-OTC switches have included hydrocortisone, antihistamine and decongestant products, antiftingal agents, and, as of 1995, several histamine H2-receptor antagonists. 

Since many of the uses of antihistamines involve conditions such as rashes, which should be treatable by local application, there is some rationale for developing drugs for topical use. The known side effects of antihistamines could in principle be avoided if the drug were functionalized so as to avoid systemic absorption. The known poor absorption of quaternary salts make such derivatives attractive for nonabsorbable antihistamines for topical use. Thus, reaction of the well-known anti his-taminic drug promethazine (104) with methyl chloride leads... 

IMPAIRED SKIN INTEGRITY. The nurse inspects die skin every 4 hours for redness, rash, or lesions that appear as red wheals or blisters. When a skin rash or irritation is present, die nurse administers frequent skin care Emollients, antipyretic creams, or a topical corticosteroid may be prescribed. An antihistamine may be prescribed. Harsh soaps and perfumed lotions are avoided. The nurse instructs the patient to avoid nibbing the area and not to wear rough or irritating clothing. 

Antihistamines are drags used to counteract the effects of histamine on body organs and structures. Examples of antihistamines include diphenhydramine (Benadryl), loratadine (Claritin), fexofenadine (Allegra), and cetirizine (Zyrtec). A new antihistamine, deslorata-dine (Clarinex), is die active metabolite of loratadine and is intended to eventually replace loratadine (Claritin). Topical corticosteroid nasal sprays such as fluticasone propionate (Flonase) or triamcinolone ace-tonide (Nasacort AQ) are also used for nasal allergy symptoms. See Chapter 56 for more information on die topical corticosteroids. 

Johnson, H.G., McNec, M.L. and Nugent, R,A. (1992). Canine in vivo tracheal chemotaxis of eosinophils to antigen in sensitized dogs inhibition by a steroid, a systemic lazaroid U-78517F, and several topical HI antihistamines. Am. Rev. Respir. Dis. 146, 621-625. 

Pharmacologic Therapy Topical emollients have been used as treatment for pruritus in patients with dry skin, but are often not effective in relieving pruritus associated with CKD. Antihistamines, such as hydroxyzine 25 to 50 mg or diphenhydramine 25 to 50 mg orally or intravenously, are used as... 

Pharmacotherapy has an important role in managing AR symptoms (Table 59-2). Intranasal corticosteroids, systemic and topical antihistamines and decongestants, mast cell stabilizers, and immunotherapy all are beneficial in treating symptoms of AR.9 Antihistamines and intranasal corticosteroids are considered first-line therapy for AR, whereas decongestants, mast cell stabilizers, leukotriene modifiers, and systemic corticosteroids are secondary treatment options10-12 (Fig. 59-2). Whenever exposure to allergens can be predicted (e.g., SAR or visiting homes with a pet), medications should be used pro-phylactically to maximize effectiveness.11... 

Intranasal anticholinergic agents (e.g., ipratropium) reduce the severity and duration of rhinorrhea but have no effect on other nasal symptoms.11,12,21 Ipratropium reduces cholinergic hyperreactivity and cholinergically mediated histamine- and antigen-induced secretion. Intranasal ipratropium acts locally, with only minimal systemic absorption. Clinical trials demonstrated that ipratropium bromide 0.3% reduced rhinorrhea in adults and children with PAR.11,12 Intranasal ipratropium is an option for patients in whom rhinorrhea is refractory to topical intranasal corticosteroids and/or antihistamines.8,12 Intranasal ipratropium is available only by prescription, and the dose is two sprays nasally two to three times daily.15 Adverse effects are minimal, but dry nasal membranes have been reported.11,12... 

Treatment of ocular allergy is aimed at slowing or stopping these processes. Antihistamines block the histamine receptors and some prevent histamine production and/or inhibit mediator release from the mast cells.15 Mast cell stabilizers inhibit the degranulation of mast cells, preventing mediator release. Some topical agents have multiple mechanisms of action, combining antihistaminic, mast cell stabilization, and antiinflammatory properties (Tables 60-3 and 60-4).16... 

If artificial tears are insufficient, the second treatment step is a topical antihistamine or antihistamine/decongestant combination. The antihistamine/decongestant combination is more effective than either agent is alone. Decongestants are vasoconstrictors that reduce redness and seem to have a small synergistic effect with the antihistamine. The only topical... 

Most maculopapular reactions disappear within a few days after discontinuing the agent, so symptomatic control of the affected area is the primary intervention. Topical corticosteroids and oral antihistamines... 

Photosensitivity reactions typically resolve with drug discontinuation. Some patients benefit from topical corticosteroids and oral antihistamines, but these are relatively ineffective. Systemic corticosteroids (e.g., oral prednisone 1 mg/kg/day tapered over 3 weeks) is more effective for these patients. 

Closed-angle glaucoma Topical anticholinergics Topical sympathomimetics Systemic anticholinergics Heterocyclic antidepressants Low-potency phenothiazines Antihistamines Ipratropium... 

Topical and systemic decongestants are sympathomimetic agents that act on adrenergic receptors in the nasal mucosa to produce vasoconstriction, shrink swollen mucosa, and improve ventilation. Decongestants work well in combination with antihistamines when nasal congestion is part of the clinical picture. 

Rhinocort Aqua and Nasonex are preparations containing topical nasal corticosteroids (budesonide and mometasone furoate respectively). Otrivine contains a nasal decongestant (xylometazoline) and Sudafed is a systemic preparation containing a nasal decongestant (phenylephrine). Molcer is a preparation for ear-wax removal and which contains docusate sodium. Emadine contains an antihistamine (emedastine) and is presented as eye drops. 

The application of a mild topical corticosteroid, such as hydrocortisone, is effective in patients presenting with multiple mosquito bites. Paracetamol, which is an antipyretic agent is not indicated in mosquito bites. Fusidic acid cream is an anti-infective agent and is indicated if the mosquito bites have been scratched and there is risk of infection. Benzocaine (anaesthetic) and mepyramine (antihistamine) may relieve itchiness but are less effective in multiple mosquito bites than hydrocortisone. 

An important example of PLP-dependent amino acid decarboxylation is the conversion of histidine into histamine. Histamine is often involved in human allergic responses, e.g. to insect bites or pollens. Stress stimulates the action of the enzyme histidine decarboxylase and histamine is released from mast cells. Topical antihistamine creams are valuable for pain relief, and oral antihistamines are widely prescribed for nasal allergies such as hay fever. Major effects of histamine include dilation of blood vessels, inflammation and swelling of tissues, and narrowing of airways. In serious cases, life-threatening anaphylactic shock may occur, caused by a dramatic fall in blood pressure. 

Inhibitors of histamine release One of the effects of the so-called mast cell stabilizers cromoglycate (cromolyn) and nedocromil is to decrease the release of histamine from mast cells (p. 72, 326). Both agents are applied topically. Release of mast cell mediators can also be inhibited by some Hi antihistamines, e.g., oxatomide and ketotifen, which are used systemically. 

Antihistamines can be administered topically (through the skin, nose, or eyes) or sys-temically, based on the nature of the allergic condition. 

---