Lorazepam tablets of the Ativan brand also contain lactose, microcrystalline cellulose, polacrilin, magnesium stearate, and coloring agents (indigo carmine in blue tablets and tartrazine in yellow tablets). Lorazepam for injection formulated with polyethylene glycol 400 in propylene glycol with 2.0% benzyl alcohol as preservative. Lorazepam injectable solution is administered either by deep intramuscular injection or by intravenous injection. The injectable solution comes in 1 mL ampoules containing 2 or 4 mg of lorazepam. The solvents used are polyethylene glycol 400 and propylene glycol. As a preservative, the injectable solution contains benzyl alcohol. Toxicity from propylene glycol has been reported in the case of a person receiving a continuous lorazepam infusion. Intravenous injections should be given slowly and they should be closely monitored for side effects, such as respiratory depression, hypotension, or loss of airway control. Peak effects roughly coincide with peak serum levels, which occur 10 minutes after intravenous injection, up to 60 minutes after intramuscular injection, and 90 to 120 minutes after oral administration, but initial effects will be noted before this. A clinically relevant lorazepam dose will normally be effective for six to 12 hours, making it unsuitable for regular once-daily administration, so it is usually prescribed as two to four daily doses when taken regularly, but this may be extended to five or six, especially in the case of elderly people who could not handle large doses at once.
A very rapid descent, usually by accident, may exceed the rate at which the breathing gas supply can equalise the pressure causing a temporary squeeze. The introduction of the non-return valve and high maximum gas supply flow rates have all but eliminated both these risks. In helmets fitted with a neck dam, the dam will admit water into the helmet if the internal pressure gets too low; this is less of a problem than helmet squeeze but the diver may drown if the gas supply is not reinstated quickly. : 90  This form of barotrauma is avoidable by controlled descent rate, which is standard practice for commercial divers, who will use shotlines, diving stages and wet bells to control descent and ascent rates. Medical screening
Professional divers are screened for risk factors during initial and periodical medical examination for fitness to dive. In most cases recreational divers are not medically screened, but are required to provide a medical statement before acceptance for training in which the most common and easy to identify risk factors must be declared. If these factors are declared, the diver may be required to be examined by a medical practitioner, and may be disqualified from diving if the conditions indicate.Asthma, Marfan syndrome, and COPD pose a very high risk of pneumothorax. In some countries these may be considered absolute contraindications, while in others the severity may be taken into consideration. Asthmatics with a mild and well controlled condition may be permitted to dive under restricted circumstances.