Labetalol infusion is used for the management of severe hypertension. Labetalol acts as an
antagonist. Labetalol blocks alpha-adrenoreceptors in peripheral arterioles, which results in
decreasing peripheral resistance. It concurrently blocks beta-adrenoreceptors in the heart
due to peripheral vasodilation that occurred during the blockage of alpha-adrenoreceptors.
Due to a decrease in peripheral resistance, peripheral vasodilation reduces blood pressure
without achieving cardiac stimulation. Labetalol establishes a precise relationship between
alpha and beta-blocking effects. In a therapeutic range of doses, labetalol is less active in
blocking alpha-adrenoreceptors than beta-adrenoreceptors; therefore, adequate vasodilation
occurs without excessive lowering in blood pressure (“Presolol”, 2021). Labetalol has a
plasma half-life of around five hours, and the peak effect is 5 to 15 minutes. The protein
binds about half of the labetalol in the blood. Labetalol is predominantly metabolised by
conjugation to inactive glucuronide metabolites. These are excreted in the urine (55-60%)
and the faeces by the bile. Only trace quantities of labetalol pass through the blood-brain
barrier. Labetalol passes through the placental membrane during pregnancy (“Labetalol”,
2021).
Paracetamol is prescribed for the relief of headache associated with migraine. It is a para-
aminophenol derivative that exhibits analgesic and antipyretic activity. It inhibits the
prostaglandin synthesis in the central nervous system and does not possess anti-
inflammatory activity which relieve pain. Paracetamol is rapidly and completely absorbed
from the GI tract after administration. The release of paracetamol ensures that the plasma
paracetamol concentrations are rapidly attained and maintained until up to eight hours after
administration. It distributes into most of the body tissues. The binding of paracetamol is
minimal with plasma proteins at therapeutic concentrations, but it increases with an
increase in dose. It is metabolised in the liver and excreted in the urine as inactive
conjugates of glucuronide and sulphate. Approximately 85% of paracetamol is excreted in
urine as free and conjugated paracetamol 24 hours after administration (“Amcal Osteo
Relief Paracetamol”, 2021).
Nifedipine is indicated for the treatment of hypertension. It acts as a calcium antagonist.
Nifedipine reduces the arterioles' vasoconstriction, which helps to decrease peripheral
resistance and consequently lowers blood pressure. At the beginning of the nifedipine
treatment, there may be an increase in the heart rate, which increase the cardiac output.
However, this increase in the cardiac output is not enough to compensate for the
vasodilation, which reduces blood pressure and maintains normal blood pressure. After oral
administration of Nifedipine, the bioavailability of the drug is 45 to 56%. 95% of the drug
is bound to albumin. It is completely metabolised in the body and only traces detected in
the urine in an unchanged form. 70-80% of the Nifedipine is excreted via the kidneys in the
form of highly water-soluble pharmacologically inactive metabolites, and the remainder is
excreted in the faeces (“Adalat”, 2021).
Diazepam is used for the management of anxiety. It provides short-term relief from the
symptoms of anxiety. Diazepam is a member of the group of benzodiazepines that exhibits
an anxiolytic and sedative effect. The generation of active metabolites helps to enhance its
action. It enhances the GABA receptor's affinity for the neurotransmitter through positive
allosteric modulation, which increases the action of released GABA on the postsynaptic
transmembrane chloride ion flux. After oral administration of Diazepam, it is rapidly and
completely absorbed by the GI tract, and peak plasma concentration reaches after 30 to 90
minutes. Diazepam widely distributes into tissues despite high binding to the plasma
proteins. It is metabolised to pharmacologically active metabolites (desmethyldiazepam)
and small amounts of oxazepam and temazepam. The elimination half-life value for
Diazepam and desmethyldiazepam is in the range of 24-48 hours and 40-100 hours
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