"Alprazolam, like other benzodiazepines, binds to specific sites on the GABAA gamma-amino-butyric acid receptor. When bound to these sites, which are referred to as benzodiazepine receptors, it modulates the effect of GABA A receptors and, thus, GABAnergic neurons. Long-term use causes adaptive changes in the benzodiazepine receptors, making them less sensitive to stimulation and less powerful in their effects.[62]
Not all withdrawal effects are evidence of true dependence or withdrawal. Recurrence of symptoms such as anxiety may simply indicate that the drug was having its expected anti-anxiety effect and that, in the absence of the drug, the symptom has returned to pretreatment levels. If the symptoms are more severe or frequent, the patient may be experiencing a rebound effect due to the removal of the drug. Either of these can occur without the patient's actually being drug-dependent.[62]
Alprazolam and other benzodiazepines may also cause the development of physical dependence, tolerance, and benzodiazepine withdrawal symptoms during rapid dose reduction or cessation of therapy after long-term treatment.[63][64] There is a higher chance of withdrawal reactions if the drug is administered in a higher dosage than recommended, or if a patient stops taking the medication altogether without slowly allowing the body to adjust to a lower-dosage regimen.[65][66][67]
In 1992, Romach and colleagues reported that dose escalation is not a characteristic of long-term alprazolam users, and the majority of patients indicated that alprazolam continued to be effective, suggesting that tolerance to the anti-anxiety effect is limited.[68]
If a patient feels the need to end treatment with alprazolam, he/she should consult his/her physician before discontinuing the medication. Some common symptoms of alprazolam discontinuation include tachycardia, dysphoria, dry mouth, loss of appetite, insomnia, anxiety, dizziness, tremors, nausea, cramps, vomiting, diarrhea, panic attacks, mood swings, heart palpitations, memory loss. Less common and more severe reactions can occur, including hallucinations, seizures or fever[69]
Patients taking a dosing regimen larger than 4 mg per day have an increased potential for dependence. This medication may cause withdrawal symptoms upon abrupt withdrawal or rapid tapering, which in some cases have been known to cause seizures. The discontinuation of this medication may also cause a reaction called rebound anxiety. Other withdrawal effects reported from discontinuing alprazolam therapy include homicidal ideation (very rare), rage reactions, hyperalertness, vivid dreams, and intrusive thoughts.[70] Grand mal seizures have occurred after abrupt withdrawal after only short-term use. Therefore, even short-term users of alprazolam should taper off of their medication slowly to avoid serious withdrawal reactions including seizures.[71][72]
Alprazolam should never be abruptly stopped if taken regularly for any length of time because severe withdrawal symptoms may occur. Severe psychosis and seizures have been reported in the medical literature from abrupt alprazolam discontinuation,[73][74] and one death occurred from withdrawal-related seizures after gradual dose reduction.[74]
In a 1983 study of patients that had taken long-acting benzodiazepines, e.g., clorazepate, for extended periods, the medications were stopped abruptly under double-blind conditions (that is, patients were receiving either placebo or the same drug they had been taking). Only 5% of patients that had been taking the drug for less than 8 months demonstrated withdrawal symptoms, but 43% of those that had been taking them for more than 8 months did, whereas, with alprazolam - a short-acting benzodiazepine - taken for 8 weeks, 35% of patients experienced significant rebound anxiety. To some degree, these older benzodiazepines are self-tapering.[75]
The benzodiazepines diazepam (Valium) and oxazepam (Serepax) have been found to produce fewer withdrawal reactions than alprazolam (Xanax) or lorazepam (Temesta/Ativan). Factors that determine the risk of psychological dependence or physical dependence and the severity of the benzodiazepine withdrawal symptoms experienced 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/cross-tolerant drugs (alcohol or other sedative-hypnotic drugs), use of other short-acting, high-potency benzodiazepines[8][76] and method of discontinuation."
