Lorazepam drug administration

Treatment begins with standard emergency procedures such as maintaining an airway, starting an IV line for blood sampling and drug administration, and so on.28 The first drugs administered are usually benzodiazepines lorazepam (Ativan) or diazepam (Valium)... 

Lorazepam shares with other benzodiazepines the ability to impair explicit memory, but has a distinct further effect on implicit memory as well (10). However, it impairs memory more than its chemically and kinetically similar analogue, oxazepam (11). The effects of lorazepam 2.5 mg and diazepam 0.3 mg/kg on explicit and implicit memory tasks have been examined in 24 men and 24 women randomly allocated to lorazepam, diazepam, or placebo (10). An implicit word-stem completion task and explicit memory tasks of immediate and delayed word recall and word recognition were administered 90 minutes after drug administration. Both diazepam and lorazepam significantly impaired performance on explicit memory measures. Only lorazepam significantly impaired performance on the implicit memory task. 

Most BZs are completely absorbed from the gastrointestinal (GI) tract. The one exception is clorazepate, a pro-drug that undergoes acid hydrolysis in the stomach and is decarboxylated to form N-desmethyl-diazepam, which is then completely absorbed into the bloodstream (Bellantuono et ak, 1980 Hobbs et ak, 1996 Chouinard et ak, 1999). In contrast, most BZs, with the exception of lorazepam and midazolam, are not consistently absorbed from intramuscular injection (Chouinard et ak, 1999). Lorazepam is available as a sublingual form that reaches clinical effect at the same rate as an oral dose. In general, intravenous administration is used only for anesthesia or for the acute management of seizures. When BZs are given via this route, the onset of action is almost immediate (Chouinard et ak, 1999). 

Diazepam, lorazepam, and midazolam are used for preanesthetic medication and as adjuvants during surgical procedures performed under local anesthesia. As a result of their sedative, anxiolytic, and amnestic properties, and their ability to control acute agitation, these compounds are considered to be the drugs of choice for premedication. (The basic pharmacology of benzodiazepines is discussed in Chapter 22.) Diazepam and lorazepam are not water-soluble, and their intravenous use necessitates nonaqueous vehicles, which cause pain and local irritation. Midazolam is water-soluble and is the benzodiazepine of choice for parenteral administration. It is important that the drug becomes lipid-soluble at physiologic pH and can readily cross the blood-brain barrier to produce its central effects. 

Consistent with their depressant and sedative effects, benzodiazepines administered acutely typically decrease CFF threshold.119 120 Specifically, significant decreases have been reported for 1 mg alprazolam, 10 mg diazepam, and 15 mg quazepam 121 4 to 11 mg midazolam 122 7.5 to 50 mg oxazepam 123 1 and 2 mg lorazepam 124 and 0.5 mg triazolam and 1 mg flunitrazepam.120 As is evident, this effect on CFF threshold was observed at therapeutic doses of each drug, and when multiple doses were tested, the effect was dose-related. However, there are reports of acute, therapeutic doses of diazepam (5 mg)125 and lorazepam (1 and 2 mg)125,126 having no effect on CFF threshold. One study investigating numerous benzodiazepines120 reported next-day impairment after acute doses of triazolam (0.5 mg) and lormetazepam (1 to 2 mg). No studies were found that examined the effect of chronic benzodiazepine administration on CFF threshold. 

Compared with focused attention, fewer studies have examined the effects of benzodiazepines on selective attention. Two studies have shown that performance on the Stroop test was impaired by lorazepam.119 131 Acute administration of triazolam and lorazepam produced dose-dependent decrements in response rate and accuracy in a simultaneous matching-to-sample task, which required subjects to determine which of two comparison visual stimuli was identical to the sample stimulus.148 161 The drug effects differed as a function of task difficulty, such that the benzodiazepine-induced impairment was reduced when discriminability of the non-matching stimulus was increased. 

BZDs OPIOIDS 1. t sedation with BZDs 2. Respiratory depressant effect of morphine is antagonized by lorazepam. 1. Additive effect both drugs are sedatives 2. Uncertain 1. Closely monitor vital signs during co-administration 2. Although this effect may be considered to be beneficial, it should be borne in mind if the combination of an opioid and BZD is used for sedation for painful procedures... 

Parenteral administration via the intramuscular route should be avoided with diazepam and chlordiazepoxide secondary to variability in the rate and extent of drug absorption. Intramuscular lorazepam provides rapid, reliable, and complete absorption however, the preparation requires refrigeration. 

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