DRASTIN ANALGESIC TABLETS

Indications

• Pain relief (analgesic)
• Reduction of inflammation (anti-inflammatory)
• Fever reduction (antipyretic)
• Cardiovascular event prevention (antiplatelet)

Dosage

Adults: Refer to specific guidelines for dosing, as it varies based on indication. For analgesia or anti-inflammatory use, doses typically range from 300 mg to 1000 mg every 4 to 6 hours. For cardiovascular protection, lower doses of 75

Mechanism of action

Aspirin irreversibly inhibits cyclooxygenase-1 (COX-1) and cyclooxygenase-2 (COX-2) enzymes, which decreases the production of prostaglandins and thromboxane A2. This action reduces inflammation and pain and prevents platelet aggregation, making it useful in the prevention of thrombotic cardiovascular events.

Pharmacodynamics

The anti-inflammatory effects of aspirin are primarily due to its ability to inhibit COX-1 and COX-2, leading to decreased synthesis of prostaglandins, which mediate inflammation and pain. The antiplatelet effect is attributed to the irreversible inhibition of thromboxane A2 production in platelets, resulting in reduced platelet aggregation and prolonged bleeding time.

Pharmacokinetics

Aspirin is rapidly absorbed from the gastrointestinal tract, with peak plasma concentrations occurring within 1 to 2 hours after oral administration. It is extensively metabolized in the liver to salicylic acid and other metabolites. The elimination half-life varies depending on the dose; at low doses, it is approximately 2 to 3 hours, while at therapeutic doses, it can be extended due to saturation of metabolism. Aspirin and its metabolites are primarily excreted by the kidneys.

Contra-indications

• Active peptic ulcer disease
• Severe hepatic impairment
• Severe renal impairment
• Hypersensitivity to acetylsalicylic acid or any of its components
• History of gastrointestinal bleeding or hemorrhagic disorders
• Asthma exacerbated by NSAIDs
• Children and adolescents with viral infections (risk of Reye's syndrome)

Adverse effects

• Gastrointestinal bleeding
• Gastritis
• Nausea
• Vomiting
• Tinnitus
• Allergic reactions (e.g., urticaria, angioedema)
• Rash
• Renal impairment
• Hepatic impairment
• Reye's syndrome in children

Interactions

• Increased risk of gastrointestinal bleeding with other NSAIDs or anticoagulants
• May enhance the effect of anticoagulants (e.g., warfarin)
• May reduce the effectiveness of some antihypertensive agents (e.g., ACE inhibitors)
• Increased risk of nephrotoxicity with certain diuretics
• May interact with methotrexate, increasing toxicity

Precautions

• Use with caution in patients with a history of peptic ulcer disease
• Monitor renal function in patients with pre-existing renal conditions
• Caution in patients with asthma or allergic conditions
• Use during pregnancy only if clearly needed, particularly in the third trimester
• Consider potential effects on platelet function in surgical patients

Pregnancy

Use during pregnancy only if clearly needed, particularly in the third trimester due to risk of bleeding and effects on fetal cardiovascular system.

Breast-feeding

Generally considered safe, but caution is advised as it can be excreted in breast milk.

Storage

Store in a cool, dry place away from direct sunlight. Keep out of reach of children.

Formulations

• Tablets
• Enteric-coated tablets
• Effervescent tablets
• Syrup
• Suppositories

Indications

• Management of apnea of prematurity
• Enhancement of alertness and cognitive performance
• Relief of headaches, particularly when combined with analgesics
• Enhancement of physical performance in sports

Dosage

Children: For infants, particularly for apnea of prematurity

Adults: The usual adult dose for alertness enhancement is 100 to 200 mg, taken as needed. For the management of apnea of prematurity, doses may vary and should be determined by a healthcare professional.

Mechanism of action

Caffeine acts primarily as an antagonist of adenosine receptors, inhibiting the action of adenosine, which normally promotes sleep and relaxation. This antagonism leads to increased neuronal firing and the release of neurotransmitters such as dopamine and norepinephrine. Caffeine also inhibits phosphodiesterase enzymes, enhancing levels of cyclic AMP and cyclic GMP, which are important for various cellular functions. Additionally, in the context of respiratory function, caffeine stimulates the respiratory centers in the central nervous system, enhancing ventilation.

Pharmacodynamics

Caffeine stimulates the central nervous system, increasing alertness and reducing fatigue. It relaxes smooth muscles, increases cardiac muscle contraction, and can enhance physical performance. Caffeine also promotes gastric acid secretion and gastrointestinal motility, and it exhibits mild diuretic properties. Its effects can lead to restlessness and agitation in some individuals, particularly at higher doses.

Pharmacokinetics

Caffeine is rapidly absorbed from the gastrointestinal tract, with peak plasma concentrations occurring within 30 to 120 minutes after ingestion. It is distributed widely throughout body tissues, readily crossing the blood-brain barrier. Caffeine is metabolized primarily in the liver by cytochrome P450 1A2, producing three primary metabolites: paraxanthine, theobromine, and theophylline. The elimination half-life varies significantly among individuals, influenced by factors such as age, liver function, pregnancy, and the use of certain medications. It is primarily excreted in urine.

Adverse effects

• Restlessness
• Agitation
• Insomnia
• Increased heart rate
• Nausea
• Gastrointestinal discomfort
• Headaches

Interactions

• caffeinecitrate+adenosine: Unknown (decreases efficacy)
• caffeinecitrate+antiarrhythmics: Unknown (decreases efficacy)

Precautions

• Use cautiously in patients with a history of anxiety disorders, insomnia, or cardiac arrhythmias.
• Monitor caffeine intake in individuals with certain medical conditions, such as hypertension.

Pregnancy

Caffeine crosses the placenta; excessive intake during pregnancy may be associated with adverse outcomes. It is generally recommended to limit caffeine consumption.

Breast-feeding

Caffeine is excreted in breast milk; moderate consumption is considered safe, but excessive intake may affect the infant's sleep and behavior.

Storage

Store in a cool, dry place away from direct light. Keep out of reach of children.

Formulations

• Tablets
• Oral solutions
• Injectable preparations
• Caffeine citrate

Mechanism of action

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. Caffeine competitively inhibits phosphodiesterase, the enzyme that degrades cyclic 3',5'-adenosine monophosphate (AMP). Increased levels of intracellular cyclic AMP mediate most of caffeine's pharmacologic actions. Caffeine stimulates all levels of the CNS... Caffeine's cortical effects are milder and of shorter duration than those of amphetamines. In slightly larger doses, caffeine stimulates medullary, vagal, vasomotor, and respiratory centers, promoting bradycardia, vasoconstriction, and increased respiratory rate. Caffeine constricts cerebral vasculature. In contrast, the drug directly dilates peripheral blood vessels...

Pharmacodynamics

Caffeine stimulates the central nervous system (CNS), heightening alertness, and sometimes causing restlessness and agitation. It relaxes smooth muscle, stimulates the contraction of cardiac muscle, and enhances athletic performance. Caffeine promotes gastric acid secretion and increases gastrointestinal motility. It is often combined in products with analgesics and ergot alkaloids, relieving the symptoms of migraine and other types of headaches. Finally, caffeine acts as a mild diuretic.