Chronic pruritus - linkages between skin & psyche, current treatment options - hydoxyzine & European guidelines on Mx of Chronic Pruritus
Upcoming SlideShare
Loading in...5
×
 

Chronic pruritus - linkages between skin & psyche, current treatment options - hydoxyzine & European guidelines on Mx of Chronic Pruritus

on

  • 434 views

 

Statistics

Views

Total Views
434
Views on SlideShare
434
Embed Views
0

Actions

Likes
0
Downloads
5
Comments
0

0 Embeds 0

No embeds

Accessibility

Upload Details

Uploaded via as Microsoft PowerPoint

Usage Rights

© All Rights Reserved

Report content

Flagged as inappropriate Flag as inappropriate
Flag as inappropriate

Select your reason for flagging this presentation as inappropriate.

Cancel
  • Full Name Full Name Comment goes here.
    Are you sure you want to
    Your message goes here
    Processing…
Post Comment
Edit your comment
  • Itch, along with pain, is a major part of nociception and an important symptom of systemic problems, as well as skin diseases. <br />
  • Itch, or pruritus, can be defined as an unpleasant sensation that evokes the desire to scratch. Although itch may be experienced acutely, chronic itch originates from many different aetiologies and is a burdensome condition with serious unmet clinical need. <br />
  • Pruriceptive itch is a sensation of itch that originates following activation of primary afferent nerve terminals. This type of itch is associated with insect bites or intradermal injection of pruritic substances, and is a very common symptom of inflammatory disorders of the skin [1]. Neuropathic itch is a chronic itch condition that results from nerve injury. Examples of neuropathic itch include itch following varicella zoster infection or nerve trauma [4]. Neurogenic itch refers to itch resulting from central nervous system activation without necessary activation of sensory nerve fibres and is thought to occur in a variety of visceral disease states such as renal disease and kidney failure. Psychogenic itch results from underlying mental illness and it often occurs with somatization and delirium <br />
  • Pruritoceptive itch <br /> Itch originating in the skin, due to inflammation,dryness, or other skin damage, is termed pruritoceptive and is transmitted by C nerve fibres. Examples are itch due to scabies, urticaria, and reactions to insect bite. <br />
  • Unmyelinated C fibres subserving the itch sensation and those subserving pain originate in the skin. Information on itch and pain is conveyed centrally in two separate systems that both use the lateral spinothalamic tract. <br />
  • General neuroanatomical and neurophysiologcial pathways activated during pruritus (pruritogenic itch). <br /> Exogenous or endogenous meditors stimulate selective subtypes of peripheral C fibre nerve endings of primary afferent neurons in the epidermis or dermis. High-affinity receptors for various pruritogenic mediators transmit the stimulus, via not completely understood intracellular signaling pathways, from the periphery to the dorsal root ganglia <br /> (DRG), and the spinal cord. DRGs can modulate this stimulus on the transcriptional and posttranscriptional level, thereby modulating peripheral and central nerve endings. Within the spinal cord, itch signals can be also modulated. From lamina 1, a selective area within the the dorsal horn of spinal cord, the signal will be transmitted to the CNS after crossing to the contralateral side. Activation of specific areas in the CNS results in the perception of itch <br /> leading to ‘discomfort’ and an acute or chronic scratch response. Additionally, the associated peripheral axon reflex may lead to the release of mast cell-stimulating neuropeptides (e.g. substance P) thereby amplifying pruritus via release of histamine, tryptase and IL-31, for example. This figure does not consider the complex interaction between pain and itch fibres on the spinal cord level where GRPR, opioid receptors, NK1R (post-synaptic), PAR2 (pre-synaptic primary afferents) and probably other mediators/ receptors can exert exciatatory or inhibitory influences. <br />
  • The enzyme semicarbazide-sensitive amine oxidase (SSAO) is involved in the pathology of chronic urticaria and pruritus. It functions as a vascular adhesion protein in mediating the early stages of inflammatory responses <br />
  • Histamine is a substrate for diamine oxidase [also a semicarbazide sensitive enzyme]. <br /> Interaction of histamine with the enzyme SSAO leads to the release of toxic chemicals causing pruritus, inflammation. <br />
  • Hydroxyzine is a derivative of piperazine not related to phenothiazines. Its main mechanism of action is an antagonism of histamine (H1) receptors. It acts by reducing activity in certain key subcortical regions such as the reticular formation and limbic system. In more than 30 years of its use there have been no documented reports of abuse, dependency or adverse effects on memory <br />
  • Hydroxyzine was found to be a potent competitive inhibitor of SSAO. <br /> By occupying the active site, hydroxyzine prevents the binding of histamine to SSAO. <br /> This prevents release of toxic chemicals thereby preventing pruritus <br />
  • Looking at the anxiety-allergy relationship we all know that psychological comorbidity is a known aspect of allergic disease. <br /> Chronic pruritus is one of the major complaints in patients who experience anxiety and a decreased quality of life. This pruritus is histamine induced so obviously there are 2 drug choices, one are the antihistamines and the other would be drugs used to treat psychological disorders. <br />
  • When we compare the mechanism of action of hydroxyzine vs a benzodiazepine,it is important to note that unlike benzodiazepines, hydroxyzine is not a direct cortico depressant. <br />
  • The benefit with hydroxyzine is its 2 in 1 action. It acts as a H1 receptor antagonist thus tackling the histamine induced pruritus. Additionally it acts as an anxiolytic thereby tackling the psychological component. <br />
  • This slide mentions the indications and dosage of hydroxyzine <br />

Chronic pruritus - linkages between skin & psyche, current treatment options - hydoxyzine & European guidelines on Mx of Chronic Pruritus Chronic pruritus - linkages between skin & psyche, current treatment options - hydoxyzine & European guidelines on Mx of Chronic Pruritus Presentation Transcript

  • Hydroxyzine SCI/2011/02/058
  • Itch Itch is a common skin sensation Lancet 2003; 361: 690–94
  • Itch Clin Exp Allergy. 2011 Jun 6 View slide
  • Itch Clin Exp Allergy. 2011 Jun 6 View slide
  • Pruritoceptive itch • Itch originating in the skin, due to – Inflammation, – Dryness, or other skin damage • Transmitted by C nerve fibers • One of the most debilitating symptoms in allergic and atopic diseases • Example: itch due to – Scabies, urticaria, and reactions to insect bite. Lancet 2003; 361: 690–94; Allergy 2010;65(7):805-21
  • Neurophysiology of itch Lancet 2003; 361: 690–94
  • Neuroanatomical and Neurophysiologcial pathways
  • Dermatological Causes of Pruritus Psychosomatic Medicine 2007;69:970–8
  • Role of histamine in pathology of itch • Histamine directly stimulates histamine type 1 (H1)‐receptors on itch‐specific C ‐ fibres • An intradermal injection of histamine causes: – An itch which begins after 30–45 s, peaks after about 2 min, then slowly declines over 10–15min  
  • Role of SSAO enzyme in pruritus J Pharmacol Exp Ther (2005) 315(2), 553-562
  • Pathology of histamine induced pruritus Histamine Toxic Chemicals SSAO Fund Clin Pharmacol 2007; 21: 467-479
  • Nocturnal Itch Acta Derm Venereol 2007; 87: 295–98
  • Nocturnal itch Acta Derm Venereol 2007; 87: 295–98
  • Nocturnal Itch: Causes • • • • Psoriasis Atopic Dermatitis Chronic Idiopathic Urticaria Cutaneous Diseases – Lichen Simplex Chronicus – Scabies • Patients With Systemic Diseases Including – Chronic Renal Failure – Hematopoietic Disorders Up to 65% of patients with inflammatory skin conditions including atopic dermatitis and chronic idiopathic urticaria have reported increased itching at night. Acta Derm Venereol 2007; 87: 295–98
  • Nocturnal itch: possible mechanisms • Decreased epidermal barrier function • Increased skin temperature • Normal circadian rhythms – Corticosteroids – Autonomic nervous system • Disruption of circadian rhythms – Opioids – Cytokines – Prostaglandin • Lack of external stimuli and distraction Acta Derm Venereol 2007; 87: 295–98
  • Nocturnal itch: Consequences • Disruption of sleep patterns • Reduction in the amount and quality of sleep • Deleterious effect on human performance, contributing to – Irritability, – Daytime somnolence, – Impaired functioning and psychological problems • Pruritus also contributes to depression, agitation, changes in eating habits, and difficulty concentrating Acta Derm Venereol 2007; 87: 295–98
  • Itch & Anxiety
  • Aim of treatment Acta Derm Venereol 2007; 87: 295–98
  • And break the vicious cycle
  • Treatment options • Emollients and moisturizers • Topical corticosteroids • Antihistamines • Topical calcineurin inhibitors • Mirtazapine Acta Derm Venereol 2007; 87: 295–98
  • Hydroxyzine Efficacious in relieving pruritus in various forms of eczema and dermatitis
  • Guidelines in Management of Chronic Pruritus
  • General measures
  • Step wise management
  • Hydroxyzine • Derivative of piperazine not related to phenothiazines • Main mechanism of action is an antagonism of histamine (H1) receptors Current ther Res 1977;22:N1 section 2; Molecular pharmacology 1992;3:78-84
  • Mechanism of action of hydroxyzine to reduce pruritus • Hydroxyzine was found to be a potent competitive inhibitor of SSAO • By occupying the active site, hydroxyzine prevents the binding of histamine to SSAO – This prevents release of toxic chemicals thereby preventing pruritus Hydroxyzine Histamine SSAO eural Transm Suppl. 2006;(71):105-12.
  • Hydroxyzine: Indications
  • Psychosomatic Medicine 2007;69:970–8
  • Anxiety-Allergy relationship • Psychological comorbidity is a known aspect of allergic disease • Chronic pruritus is one of the major complaints in these patients – Patients experience anxiety and decreased quality of life • The pruritus is histamine induced • 2 therapeutic choices – Antihistamines – Drugs used to treat psychological disorders Br J of Dermatology 2006; 154(6):1128-36
  • MOA of hydroxyzine as an Anxiolytic Acta Psychiatr Scand 1998; suppl 393:102-108
  • Benefits with hydroxyzine • 2 in 1 action – Acts as an H1 receptor antagonist • Tackles pruritus – Acts as an anxiolytic
  • To conclude…. • Efficacious in relieving pruritus in various forms of urticaria, eczema and dermatitis 1 – Most potent antihistamine in alleviating IgEmediated pruritus2 – Suppresses the wheal-and-flare response for greater than 24 hours2 – Antihistaminic effect begins approximately after 1 hour with oral formulation1 – Clinically significant anxiolytic effect3 1. Hydroxyzine Prescribing Information Version 1.0-2009 2. Micromedex Health Care Series, accessed on 12/03/2009, 3. Encephale. 1994;20(6):785-91.
  • Abbreviated Prescribing Information • • • • Composition: Each film-coated tablet contains 10 mg of hydroxyzine dihydrochloride. Each film-coated tablet contains 25 mg of hydroxyzine dihydrochloride. Each ml of syrup contains 5 mg of hydroxyzine dihydrochloride. Each ml of solution for injection contains 25 mg of hydroxyzine dihydrochloride, and an ampoule containing 2 ml of solution for injection contains 50 mg of hydroxyzine dihydrochloride. Each ml of oral drops contains 6mg of hydroxyzine dihydrochloride USP. Therapeutic indications hydroxyzine is indicated in: the symptomatic treatment of anxiety in adults; the symptomatic treatment of pruritus; the premedication before surgery. Posology and method of administration hydroxyzine solution for injection is intended to be administered by the intramuscular route. Adults For symptomatic treatment of anxiety: 50 mg/day in 3 separate administrations of 12.5-12.5-25 mg; in more severe cases doses of up to 300 mg/day can be used. For symptomatic treatment of pruritus: Starting dose of 25 mg before resting, to be followed if necessary with doses up to 25 mg 3 to 4 times daily. For premedication before surgery: 50 to 200 mg/day in 1or 2 administrations: single administration 1 hour before surgery, which may be preceded by 1 administration the night before anaesthesia. Children (from 12 months) – For symptomatic treatment of pruritus: from 12 months to 6 years old: 1 mg/kg/day up to 2.5 mg/kg/day in divided doses, over 6 years old 1 mg/kg/day up to 2 mg/kg/day in divided doses. – For premedication before surgery: Single administration of 1 mg/kg 1 hour before surgery, which may be preceded by 1 mg/kg the night before anaesthesia. Contra-indications History of hypersensitivity to any of the constituents of hydroxyzine, to cetirizine, to other piperazine derivatives, to aminophylline, or to ethylenediamine. Patients suffering from porphyria. Pregnancy and breast-feeding Fructose intolerance, glucose-galactose mal-absorption or sucrase-isomaltase Galactose intolerance, the Lapp lactase deficiency or glucose-galactose malabsorption.
  • Abbreviated Prescribing Information • • Special warnings and precautions for use – Concomitant use of hydroxyzine with alcohol. – hydroxyzine should be administered cautiously in patients with increased potential for convulsions & cardiac arrhythmia, in patients suffering from glaucoma, bladder outflow obstruction, decreased gastro-intestinal motility, myasthenia gravis, or dementia. – Dosage adjustments may be required if used simultaneously with other CNS depressant drugs or with drugs having anticholinergic properties. – Patients should be cautioned against driving a car or operating machinery, as hydroxyzine may impair the ability to react and to concentrate. – In the elderly, it is advised to start with half the recommended dose due to a prolonged action. – hydroxyzine dosage should be reduced in patients with hepatic dysfunction and with moderate or severe renal impairment. – Before intramuscular administration of hydroxyzine solution for injection, careful check that the needle did not enter any vessel must be performed. – hydroxyzine 2 mg/ml syrup contains 0.1 vol % of alcohol, this has to be taken into account in alcoholics, in pregnant or lactating women, children, and high-risk groups such as patients with liver disease, or epilepsy. – hydroxyzine antagonizes the effects of betahistine, and of anticholinesterase drugs. – Simultaneous administration of hydroxyzine with monoamine oxidase inhibitors should be avoided. Side-effects The following undesirable effects have been reported: – Very common: somnolence – Common: dry mouth, fatigue, headache, sedation, agitation, confusion, – Uncommon: nausea, malaise, pyrexia, dizziness, insomnia, tremor – Rare: tachycardia, accommodation disorder, vision blurred, constipation, vomiting, hypersensitivity, liver function test abnormal, convulsions, dyskinesia, disorientation, hallucination, urinary retention, pruritus, rash erythematous, rash maculo-papular, urticaria, dermatitis, hypotension – Very rare: anaphylactic shock, bronchospasm, angioneurotic oedema, sweating increased, fixed drug eruption Please refer to full prescribing information before usage
  • ?