Basic research on the pharmacology of itch has exploded in the wake of two very influential
papers that were published in Nature (2007) and Science (2009). Long overlooked as a milder
form of pain itching has rapidly gained a new appreciation in both research and clinical
communities because of its complexity and its negative effects on the quality of life of the
distressed patients. Like pain not all itches are the same. Unlike pain there are no standard
drugs equivalent to aspirin and morphine. Epidemiological studies emphasize the high incidence
and economic costs of itch (pruritus). It is the most prevalent symptom of a wide variety of
allergic and inflammatory skin conditions (e.g. psoriasis atopic dermatitis) is associated
with several systemic diseases (e.g. chronic kidney and liver disease) and occurs in patients
undergoing hemodialysis spinal administration of opioids and in those suffering from AIDS.
The reader will learn about the multiple pathways for itch and their interactions with pain.
The relationship between these closely related yet distinct sensory phenomena will be
emphasized. Both itch and pain use several common molecules to send signals to the brain. Thus
drugs that have been and are being developed as analgesics may also attenuate intractable
itch. This has been an exciting and very necessary turn of events since traditional H-1
receptor antagonists are ineffective in blocking the pruritus associated with kidney failure
and cholestasis. The clinical chapters will provide insights into contemporary treatment
regimens for pruritus in different human scenarios.
