Drugs
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Review
Remifentanil: a review of its use during the induction and maintenance of general anaesthesia.
Remifentanil (Ultiva), a fentanyl derivative, is an ultra-short acting, nonspecific esterase-metabolised, selective mu-opioid receptor agonist, with a pharmacodynamic profile typical of opioid analgesic agents. Notably, the esterase linkage in remifentanil results in a unique and favourable pharmacokinetic profile for this class of agent. ⋯ Remifentanil is efficacious in combination with intravenous or volatile hypnotic agents, with these regimens generally being at least as effective as fentanyl- or alfentanil-containing regimens in terms of attenuation of haemodynamic, autonomic and somatic intraoperative responses, and postoperative recovery parameters. The rapid offset of action and short context-sensitive half-time of remifentanil, irrespective of the duration of the infusion, makes the drug a valuable opioid analgesic option for use during balanced general inhalational or total intravenous anaesthesia (TIVA) where rapid, titratable, intense analgesia of variable duration, and a fast and predictable recovery are required.
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Meconium aspiration syndrome (MAS) is an important cause of respiratory distress in the term infant. Therapy for the disease remains problematic, and newer treatments such as high-frequency ventilation and inhaled nitric oxide are being applied with increasing frequency. There is a significant disturbance of the pulmonary surfactant system in MAS, with a wealth of experimental data indicating that inhibition of surfactant function in the alveolar space is an important element of the pathophysiology of the disease. ⋯ Combined animal and human data suggest that lung lavage can remove significant amounts of meconium and alveolar debris, and thereby improve oxygenation and pulmonary mechanics. Arterial oxygen saturation inevitably falls during lavage but has been noted to recover relatively rapidly, even in infants with severe disease. Several randomised controlled trials of surfactant lavage in MAS are underway, and until the results are known, lavage must be considered an unproven and experimental therapy.
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Ropivacaine (Naropin) is the pure S(-)-enantiomer of propivacaine, and is a long-acting amide local anaesthetic agent, eliciting nerve block via reversible inhibition of sodium ion influx in nerve fibres. Ropivacaine is a well tolerated regional anaesthetic effective for surgical anaesthesia as well as the relief of postoperative and labour pain. ⋯ Clinically adequate doses of ropivacaine appear to be associated with a lower incidence or grade of motor block than bupivacaine. Thus ropivacaine, with its efficacy, lower propensity for motor block and reduced potential for CNS toxicity and cardiotoxicity, appears to be an important option for regional anaesthesia and for the management of postoperative and labour pain.
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Subcutaneous recombinant interferon-beta-1a (Rebif) 22 or 44 microg three times weekly is a valuable option in the first-line treatment in patients with relapsing-remitting multiple sclerosis (RRMS). It has shown benefits on outcome measures related to relapses, progression of disability and magnetic resonance imaging (MRI) in clinical trials. ⋯ The most common adverse events are generally mild and clinically manageable. Considering both direct and indirect comparative clinical trial data, an assessment suggests that subcutaneous interferon-beta-1a 44 microg three times weekly has the best benefit-to-risk values of the available disease-modifying drugs used to treat RRMS.
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Pregabalin, the pharmacologically active S-enantiomer of 3-aminomethyl-5-methyl-hexanoic acid, has a similar pharmacological profile to that of its developmental predecessor gabapentin, but showed greater analgesic activity in rodent models of neuropathic pain. The exact mechanism of action of pregabalin is unclear, although it may reduce excitatory neurotransmitter release by binding to the alpha2-delta protein subunit of voltage-gated calcium channels. Oral pregabalin 150-600 mg/day, administered twice or three times daily, was superior to placebo in relieving pain and improving pain-related sleep interference in three randomised, double-blind, placebo-controlled, multicentre studies of 8-13 weeks' duration in a total of 776 evaluable patients with postherpetic neuralgia (PHN). ⋯ In two studies, significant improvements in daily mean pain scores were apparent on the first or second day of treatment with pregabalin administered three times daily. Pregabalin was generally well tolerated when force-titrated over 1 week to fixed dosages (maximum 600 mg/day) in clinical trials that enrolled most elderly PHN patients. Dizziness, somnolence and peripheral oedema of mild-to-moderate intensity were the most common adverse events.