Neza

Uses

Caffeine is a stimulant present in tea, coffee, cola beverages, analgesic drugs, and agents used to increase alertness. It is also used in to prevent and treat pulmonary complications of premature birth.

Caffeine is indicated for the short term treatment of apnea of prematurity in infants and off label for the prevention and treatment of bronchopulmonary dysplasia caused by premature birth. In addition, it is indicated in combination with sodium benzoate to treat respiratory depression resulting from an overdose with CNS depressant drugs. Caffeine has a broad range of over the counter uses, and is found in energy supplements, athletic enhancement products, pain relief products, as well as cosmetic products.

Phenylephrine is an alpha-1 adrenergic agonist used in the management of hypotension, generally in the surgical setting associated with the use of anesthetics.

Phenylephrine injections are indicated to treat hypotension caused by shock or anesthesia, an ophthalmic formulation is indicated to dilate pupils and induce vasoconstriction, an intranasal formulation is used to treat congestion, and a topical formulation is used to treat hemorrhoids. Off-label uses include situations that require local blood flow restriction such as the treatment of priapism.

Neza is also used to associated treatment for these conditions: Bronchopulmonary Dysplasia (BPD), Common Cold, Dark circles under eyes, Dyspepsia, Fatigue, Fever, Flu caused by Influenza, Headache, Migraine, Pain, Pain, Acute, Pain, Menstrual, Primary apnea of premature newborns, Respiratory Depression, Rheumatic Pain, Somnolence, Soreness, Muscle, Tension Headache, Toothache, Moderate Pain, Analgesia, Antacid therapy, Athletic PerformanceAllergic Rhinitis (AR), Anorectal discomfort, Cold, Common Cold, Common Cold/Flu, Congestion of the Conjunctivas, Conjunctivitis allergic, Cough, Cough caused by Common Cold, Eye allergy, Eye redness, Fever, Flu caused by Influenza, Headache, Headache caused by Allergies, Headache caused by Common Cold, Headache caused by Pollen Allergy, Hemorrhoids, Hypotension, Irritative cough, Itching of the nose, Itching of the throat, Laryngotracheitis, Nasal Congestion, Nose discomfort, Ocular Inflammation, Ocular Irritation, Paroxysmal Supraventricular Tachycardia, Pollen Allergy, Respiratory tract congestion, Respiratory tract irritation, Rhinopharyngitis, Rhinorrhoea, Seasonal Allergies, Shock, Cardiogenic, Sinus Congestion, Sinus pressure, Sinusitis, Sneezing, Sore Throat, Tracheobronchitis, Upper respiratory tract hypersensitivity reaction, site unspecified, Vasomotor Rhinitis, Aching caused by Flu caused by Influenza, Bronchial congestion, Itchy throat, Minor aches and pains, Watery itchy eyes, Airway secretion clearance therapy, Antihistamine, Dilatation of the pupil, Vasoconstrictor in regional analgesia therapy

How Neza works

The mechanism of action of caffeine is complex, as it impacts several body systems, which are listed below. The effects as they relate to various body systems are described as follows:

General and cellular actions

Caffeine exerts several actions on cells, but the clinical relevance is poorly understood. One probable mechanism is the inhibition of nucleotide phosphodiesterase enzymes, adenosine receptors, regulation of calcium handling in cells, and participates in adenosine receptor antagonism. Phosphodiesterase enzymes regulate cell function via actions on second messengers cAMP and cGMP. This causes lipolysis through activation of hormone-sensitive lipases, releasing fatty acids and glycerol.

Respiratory

The exact mechanism of action of caffeine in treating apnea related to prematurity is unknown, however, there are several proposed mechanisms, including respiratory center stimulation in the central nervous system, a reduced threshold to hypercapnia with increased response, and increased consumption of oxygen, among others. The blocking of the adenosine receptors enhances respiratory drive via an increase in brain medullary response to carbon dioxide, stimulating ventilation and respiratory drive, while increasing contractility of the diaphragm.

Central nervous system

Caffeine demonstrates antagonism of all 4 adenosine receptor subtypes (A1, A2a, A2b, A3) in the central nervous system. Caffeine's effects on alertness and combatting drowsiness are specifically related to the antagonism of the A2a receptor.

Renal system

Caffeine has diuretic effects due to is stimulatory effects on renal blood flow, increase in glomerular filtration, and increase in sodium excretion.

Cardiovascular system

Adenosine receptor antagonism at the A1 receptor by caffeine stimulates inotropic effects in the heart. Blocking of adenosine receptors promotes catecholamine release, leading to stimulatory effects occurring in the heart and the rest of the body. In the blood vessels, caffeine exerts direct antagonism of adenosine receptors, causing vasodilation. It stimulates the endothelial cells in the blood vessel wall to release nitric oxide, potentiating blood vessel relaxation. Catecholamine release, however, antagonizes this and exerts inotropic and chronotropic effects on the heart, ultimately leading to vasoconstriction. Finally, caffeine is shown to raise systolic blood pressure measurements by 5 to 10 mmHg when it is not taken regularly, versus no effect in those who consume it regularly. The vasoconstricting effects of caffeine are beneficial in migraines and other types of headache, which are normally caused by vasodilation in the brain.

Phenylephrine is an alpha-1 adrenergic agonist that mediates vasoconstriction and mydriasis depending on the route and location of administration. Systemic exposure to phenylephrine also leads to agonism of alpha-1 adrenergic receptors, raising systolic and diastolic pressure as well as peripheral vascular resistance. Increased blood pressure stimulates the vagus nerve, causing reflex bradycardia.

Toxicity

The oral LD50 of caffeine in rats is 192 mg/kg. An acute fatal overdose of caffeine in humans is about 10–14 grams (equivalent to 150–200 mg/kg of body weight).

Caffeine overdose

In the case of caffeine overdose, seizures may occur, as caffeine is a central nervous system stimulant. It should be used with extreme caution in those with epilepsy or other seizure disorders. Symptoms of overdose may include nausea, vomiting, diarrhea, and gastrointestinal upset. Intoxication with caffeine is included in the World Health Organization’s International Classification of Diseases (ICD-10). Agitation, anxiety, restlessness, insomnia, tachycardia, tremors, tachycardia, psychomotor agitation, and, in some cases, death can occur, depending on the amount of caffeine consumed. Overdose is more likely to occur in individuals who do not consume caffeine regularly but consume energy drinks.

Overdose management

For a mild caffeine overdose, offer symptomatic treatment. In the case of a severe overdose, intubation for airway protection from changes in mental status or vomiting may be needed. Activated charcoal and hemodialysis can prevent further complications of an overdose and prevent absorption and metabolism. Benzodiazepine drugs can be administered to prevent or treat seizures. IV fluids and vasopressors may be necessary to combat hypotension associated with caffeine overdose. In addition, magnesium and beta blocking drugs can be used to treat arrhythmias that may occur, with defibrillation and resuscitation if the arrhythmias are lethal. Follow local ACLS protocols.

Patients experiencing and overdose may present with headache, hypertension, reflex bradycardia, tingling limbs, cardiac arrhythmias, and a feeling of fullness in the head. Overdose may be treated by supportive care and discontinuing phenylephrine, chronotropic medications, and vasodilators. Subcutaneous phentolamine may be used to treat tissue extravasation.

Volume of Distribution

Caffeine has the ability to rapidly cross the blood-brain barrier. It is water and fat soluble and distributes throughout the body. Caffeine concentrations in the cerebrospinal fluid of preterm newborns are similar to the concentrations found in the plasma. The mean volume of distribution of caffeine in infants is 0.8-0.9 L/kg and 0.6 L/kg in the adult population.

The volume of distribution of phenylephrine is 340L.

Elimination Route

Caffeine is rapidly absorbed after oral or parenteral administration, reaching peak plasma concentration within 30 minutes to 2 hours after administration. After oral administration, onset of action takes place within 45 to 1 hour. Food may delay caffeine absorption. The peak plasma level for caffeine ranges from 6-10mg/L. The absolute bioavailability is unavailable in neonates, but reaches about 100% in adults.

Phenylephrine is 38% orally bioavailable. Clinically significant systemic absorption of ophthalmic formulations is possible, especially at higher strengths and when the cornea is damaged.

Half Life

In an average-sized adult or child above the age of 9, the half-life of caffeine is approximately 5 hours. Various characteristics and conditions can alter caffeine half-life. It can be reduced by up to 50% in smokers. Pregnant women show an increased half-life of 15 hours or higher, especially in the third trimester. The half-life in newborns is prolonged to about 8 hours at full-term and 100 hours in premature infants, likely due to reduced ability to metabolize it. Liver disease or drugs that inhibit CYP1A2 can increase caffeine half-life.

Intravenous phenylephrine has an effective half life of 5 minutes and an elimination half life of 2.5 hours.

Clearance

The clearance of caffeine varies, but on average, is about 0.078 L/kg/h (1.3 mL/min/kg).

Phenylephrine has an average clearance of 2100mL/min.

Elimination Route

The major metabolites of caffeine can be found excreted in the urine. About 0.5% to 2% of a caffeine dose is found excreted in urine, as it because it is heavily absorbed in the renal tubules.

86% of a dose of phenylephrine is recovered in the urine with 16% as the unmetabolized drug, 57% as the inactive meta-hydroxymendelic acid, and 8% as inactive sulfate conjugates.

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