This medication may cause withdrawal symptoms upon abrupt withdrawal or rapid tapering, which in some cases have been known to cause seizures, as well as marked delirium similar to that produced by the anticholinergic tropane alkaloids of Datura (scopolamine and atropine). The discontinuation of this medication may also cause a reaction called rebound anxiety. In a 1983 study, only 5% of patients who had abruptly stopped taking long-acting benzodiazepines after less than 8 months demonstrated withdrawal symptoms, but 43% of those who had been taking them for more than 8 months did. With alprazolam – a short-acting benzodiazepine – taken for 8 weeks, 65% of patients experienced significant rebound anxiety. To some degree, these older benzodiazepines are self-tapering.The benzodiazepines diazepam and oxazepam have been found to produce fewer withdrawal reactions than alprazolam, temazepam, or lorazepam. Factors that determine the risk of psychological dependence or physical dependence and the severity of the benzodiazepine withdrawal symptoms during dose reduction of alprazolam include: dosage used, length of use, frequency of dosing, personality characteristics of the individual, previous use of cross-dependent/cross-tolerant drugs (alcohol or other sedative-hypnotic drugs), current use of cross-dependent/-tolerant drugs, use of other short-acting, high-potency benzodiazepines, and method of discontinuation. Pharmacology
Alprazolam is a positive allosteric modulator of the gamma-aminobutyric acid (GABA) type A receptor. When it binds to the receptor, effects of GABA are enhanced leading to inhibition of neurons in the brain. This results in effects including reduced anxiety, muscle relaxant, antidepressant and anticonvulsant activity. The activity of alprazolam in the central nervous system is dose dependent.
A biopsy of the retina and choroid layer may be performed. In affected liver, biopsy shows focal areas of necrosis and sinusoidal widening. H&E staining show extracellular frothy pink material. Typical cysts with a solid dark dot can be seen using a Grocott silver stain. Differential diagnosis
Pneumocystosis may appear similar to pulmonary embolism or adult respiratory distress syndrome. Other infections can present similarly such as tuberculosis, Legionella, and severe flu. Prevention
There is no vaccine that prevents pneumocystosis. Trimethoprim/sulfamethoxazole (co-trimoxazole) might be prescribed for people at high risk. Treatment
Treatment is usually with co-trimoxazole. Other options include pentamidine, dapsone and atovaquone. Outcomes
It is fatal in 10-20% of people with HIV/AIDS. Pneumocystosis in people without HIV/AIDS is frequently diagnosed late and the death rate is therefore higher; 30-50%. Epidemiology
The exact number of people in the world affected is not known. Pneumocystosis affects lungs in around 97% of cases and is often fatal without treatment. History
The first cases of pneumocystosis affecting lungs were described in premature infants in Europe following the Second World War. It was then known as plasma cellular interstitial pneumonitis of the newborn.Pneumocystis jirovecii (previously called Pneumocystis carinii) is named for Otto Jírovec, who first described it in 1952. == References ==