Pathergy is a skin condition in which a minor trauma such as a bump or bruise leads to the development of skin lesions or ulcers that may be resistant to healing. Pathergy can also lead to ulcerations at the site of surgical incisions. Pathergy is seen with both Behçets disease and pyoderma gangrenosum. A highly similar phenomenon known as the Koebner phenomenon occurs in autoimmune diseases such as psoriasis and systemic lupus erythematosus, among others. Doctors looking toward a diagnosis of Behçets disease may attempt to induce a pathergy reaction with a test known as a "skin prick test". The inflammation and ulceration that occurs as a result of pathergy in pyoderma gangrenosum often responds to systemic steroid therapy. The pathergy reaction is a unique feature of Behçets disease and, according to the International Study Group for Behcets Disease, is among the major criteria required for the diagnosis. Different positive pathergy reaction rates in BD have been reported worldwide. When BD-positive groups are studied for pathergy reaction, the pathergy-positive and pathergy-negative BD groups showed a similar male: female ratio, age at disease onset, and mean disease duration. They also exhibited similar HLA-B51 levels and a similar frequency of oral ulcerations in close family members. The mucocutaneous manifestations, systemic disease expression, and severity score were similar in patients with and without the pathergy reaction.
Recreational
In the 1970s, recreational drug users discovered that combining pentazocine with tripelennamine (a first-generation ethylenediamine antihistamine most commonly dispensed under the brand names Pelamine and Pyribenzamine) produced a euphoric sensation. Since tripelennamine tablets are typically blue in color and brand-name Pentazocine is known as Talwin (hence "Ts"), the pentazocine/tripelennamine combination acquired the slang name Ts and blues. After health-care professionals and drug-enforcement officials became aware of this scenario, the mu opioid receptor antagonist naloxone was added to oral preparations containing pentazocine to prevent perceived "misuse" via injection, and the reported incidence of its recreational use has declined precipitously since. Research
In an open-label, add-on, single-day, acute-dose small clinical study, pentazocine was found to rapidly and substantially reduce symptoms of mania in individuals with bipolar disorder that were in the manic phase of the condition. It was postulated that the efficacy observed was due to κ-opioid receptor activation-mediated amelioration of hyperdopaminergia in the reward pathways. Minimal sedation and no side effects including psychotomimetic effects or worsening of psychosis were observed at the dose administered. Adverse effects
Side effects are similar to those of morphine, but pentazocine, due to its action at the kappa opioid receptor is more likely to invoke psychotomimetic effects. High dose may cause high blood pressure or high heart rate. It may also increase cardiac work after myocardial infarction when given intravenously and hence this use should be avoided where possible.