PANTEX injection

Indications

• Acute pain
• Moderate to severe pain
• Obstetric analgesia
• Premedication before surgery

Dosage

Adults: By mouth: 50–150 mg every 4 hours; Subcutaneous or intramuscular injection: 25–100 mg, then 25–100 mg after 4 hours; Maximum daily dose: 600 mg. For obstetric analgesia: 30 mg every 3–4 hours as required, maximum 360 mg per day. For premedication: 45–60 mg every 3–4 hours as required, maximum 360 mg per day.

Mechanism of action

Pentazocine acts as an agonist at kappa opioid receptors and has weak antagonist activity at mu opioid receptors. By competing for opioid receptor sites, it mitigates the effects of endogenous and exogenous opioids. The analgesic properties arise mainly from its action on kappa1-opioid receptors, which triggers the analgesic pathway in the central nervous system.

Pharmacodynamics

Pentazocine is a potent analgesic, with a 50 mg oral dose providing analgesic effects comparable to 60 mg of codeine. Its onset of action typically occurs within 15 to 30 minutes, with effects lasting for three hours or more. The degree of analgesia is dose-dependent and influenced by the severity of pre-existing pain. Notably, pentazocine weakly antagonizes the effects of morphine and meperidine, providing some reversal of their respiratory and cardiovascular depressant actions.

Pharmacokinetics

Pentazocine is rapidly absorbed following oral administration, with peak plasma concentrations achieved within 1 to 2 hours. It undergoes hepatic metabolism, and its pharmacokinetic profile is influenced by factors such as age and liver function. The elimination half-life is approximately 2 to 4 hours, with renal excretion of metabolites playing a significant role in clearance.

Contra-indications

• Acute porphyrias
• Heart failure secondary to chronic lung disease
• Patients dependent on opioids (risk of precipitating withdrawal)

Adverse effects

• Sedation
• Respiratory depression
• Dysphoria
• Psychotomimetic effects
• Nausea
• Vomiting
• Constipation

Interactions

• CNS depressants (e.g., alcohol, benzodiazepines) may enhance sedative effects
• Opioid agonists may have reduced efficacy when used concurrently

Precautions

• Caution in patients with arterial hypertension
• Cardiac arrhythmias
• Myocardial infarction
• Pancreatitis
• Pheochromocytoma
• Pulmonary hypertension

Pregnancy

Use in pregnancy only if clearly needed, as safety during pregnancy has not been established.

Breast-feeding

Caution is advised; pentazocine may be excreted in breast milk.

Storage

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

Formulations

• Pentazocine 25 mg tablets
• Pentazocine 50 mg capsules

Indications

• Electrolyte replacement
• Volume expansion in hypovolemic patients
• Management of hyponatremia
• Support in intravenous fluid therapy

Dosage

Children: Refer to the BNF for Children for appropriate dosing in paediatric patients, as dosages may vary based on the formulation and clinical condition.

Adults: Refer to specific product information or clinical guidelines for dosage recommendations, as disodium is often part of combination products.

Mechanism of action

Disodium compounds often function by providing sodium ions that are essential for various physiological processes. Sodium ions play a critical role in maintaining osmotic balance, nerve impulse transmission, and muscle contraction. In the context of intravenous solutions, disodium helps to restore electrolyte balance in patients.

Pharmacodynamics

The pharmacodynamics of disodium is primarily related to its role in electrolyte balance and fluid homeostasis. Sodium ions are vital for the function of excitable tissues, including neurons and muscle cells. Changes in sodium levels can affect blood pressure, hydration status, and overall cellular function.

Pharmacokinetics

The pharmacokinetics of disodium compounds depend on their specific formulation and route of administration. When administered intravenously, disodium is rapidly distributed in the extracellular fluid, where it helps to maintain osmotic pressure. Sodium is primarily excreted by the kidneys, and its levels can be influenced by fluid intake, dietary sodium, and renal function.

Pregnancy

Use with caution. Consult a healthcare provider for specific guidance.

Breast-feeding

Use with caution. Consult a healthcare provider for specific guidance.

Storage

Store at room temperature, away from moisture and direct sunlight.

Indications

• Lead poisoning
• Mercury poisoning
• Calcium overload
• Certain diagnostic procedures involving heavy metals

Dosage

Children: Refer to the BNF for Children for appropriate dosing information tailored for paediatric patients.

Adults: Refer to the BNF for specific dosing guidelines based on the condition being treated, considering factors such as the severity of metal poisoning and renal function.

Mechanism of action

Edetate functions by forming stable complexes with divalent and trivalent metal ions, including lead and calcium, through its multiple carboxylate and amine groups. This chelation renders the metals more soluble and promotes their renal excretion, thereby reducing their toxic effects in the body.

Pharmacodynamics

The chelation of metals by edetate decreases the free metal concentration in the bloodstream, which mitigates the toxic effects associated with heavy metal accumulation. The efficacy of edetate in removing metals such as lead has been well documented, and its ability to bind calcium can influence calcium homeostasis in certain clinical scenarios.

Pharmacokinetics

Edetate is administered intravenously, with rapid distribution throughout the extracellular fluid. It is primarily excreted unchanged by the kidneys. The onset of action occurs quickly after administration, and the duration depends on the dose and the patient's renal function. The elimination half-life is approximately 1 hour but may vary based on renal clearance.

Contra-indications

• Hypersensitivity to edetate or any component of the formulation
• Severe renal impairment
• Active bleeding disorders

Adverse effects

• Hypocalcemia
• Nausea
• Vomiting
• Diarrhea
• Abdominal pain
• Headache
• Rash
• Fever

Interactions

• May enhance the effects of anticoagulants
• Concurrent use with calcium supplements may reduce effectiveness
• May interfere with the absorption of certain medications due to changes in gastrointestinal motility

Precautions

• Use with caution in patients with renal impairment
• Monitor electrolyte levels, particularly calcium, during treatment
• Assess the patient's hydration status before administration

Pregnancy

Limited data on the use of edetate in pregnancy. Use only if the potential benefit justifies the potential risk to the fetus.

Breast-feeding

Caution is advised as it is not known whether edetate is excreted in human milk. Weigh the risks and benefits before use.

Storage

Store in a cool, dry place, protected from light. Do not freeze.

Formulations

• Edetate disodium injection
• Edetate calcium disodium injection

Indications

• Pain management
• Vaccination
• Antibiotic therapy
• Hormonal therapies
• Anesthesia
• Nutritional support
• Chemotherapy

Dosage

Children: Refer to specific drug guidelines for paediatric dosing, as it requires careful consideration of weight and age.

Adults: Refer to specific drug guidelines for adult dosing, as it varies widely depending on the medication and clinical condition.

Mechanism of action

The mechanism of action of injected drugs varies widely based on the specific medication being administered. Generally, injected drugs enter the bloodstream directly, allowing them to circulate rapidly throughout the body. For instance, antibiotics may work by inhibiting bacterial cell wall synthesis, while analgesics may modulate pain pathways in the central nervous system. Each drug has unique pathways through which it achieves its therapeutic effects.

Pharmacodynamics

Pharmacodynamics refers to the effects of drugs on the body and their mechanisms of action. For injectable medications, effects can be immediate or delayed, depending on the drug's formulation and route of administration. Factors influencing pharmacodynamics include receptor affinity, drug concentration, and the presence of other substances that may enhance or inhibit the drug's effects. For example, some injectable drugs may require specific receptors to exert their effects, while others may have a broader range of action.

Pharmacokinetics

Pharmacokinetics involves the absorption, distribution, metabolism, and excretion (ADME) of injected drugs. After administration, drugs are rapidly absorbed into the bloodstream, leading to quick therapeutic effects. The distribution depends on factors such as blood flow, tissue permeability, and protein binding. Drugs are metabolized primarily in the liver and excreted through the kidneys or bile. The pharmacokinetic profile can vary widely based on the drug's chemical nature, dosage, and individual patient factors.

Pregnancy

Safety during pregnancy depends on the specific injection and its active ingredients. It is essential to consult a healthcare professional for guidance.

Breast-feeding

The safety of injections during breastfeeding varies by the specific medication. It is recommended to seek advice from a healthcare provider.

Storage

Store injections as per manufacturer's guidelines, usually in a cool, dry place away from direct sunlight. Some may require refrigeration.

Indications

• Metabolic acidosis
• Lactic acidosis
• Support in shock or severe dehydration
• Exercise physiology research

Dosage

Children: Refer to clinical guidelines for specific dosing recommendations based on the clinical condition being treated.

Adults: Refer to clinical guidelines for specific dosing recommendations based on the clinical condition being treated.

Mechanism of action

Lactic acid primarily functions by contributing to the acid-base balance in the body. It can serve as a substrate for gluconeogenesis in the liver and is utilized in the Cori cycle, where it is converted back to glucose. Furthermore, lactic acid can act as a signaling molecule in various physiological processes, influencing metabolism and cellular responses during hypoxic conditions.

Pharmacodynamics

Lactic acid dissociates into lactate and hydrogen ions in solution, which can lead to a decrease in pH (acidosis) when produced in excess. Its accumulation in the body is indicative of anaerobic metabolism, often observed during intense exercise or in conditions of oxygen deprivation. The body can buffer the effects of lactic acid through bicarbonate and other mechanisms, maintaining homeostasis.

Pharmacokinetics

Lactic acid is rapidly absorbed and distributed throughout the body. It is metabolized primarily in the liver, where it can be converted to glucose or further metabolized to carbon dioxide and water. The elimination half-life of lactate varies depending on the metabolic state of the individual and the presence of underlying conditions. Renal function also plays a role in the clearance of lactate from the body.

Adverse effects

• Nausea
• Vomiting
• Abdominal pain
• Diarrhea
• Hypersensitivity reactions

Precautions

• Use with caution in patients with renal impairment
• Monitor for signs of metabolic acidosis
• Caution in patients with liver disease

Pregnancy

Lactic acid is generally regarded as safe, but clinical use should be evaluated on a case-by-case basis during pregnancy.

Breast-feeding

Considered safe for use during breastfeeding, but consult healthcare provider for individual cases.

Storage

Store at room temperature, away from direct sunlight and moisture.

Formulations

• Lactic acid injection
• Lactic acid oral solution

Mechanism of action

The preponderance of evidence suggests that pentazocine antagonizes the opioid effects by competing for the same receptor sites, especially the opioid mu receptor. /Pentazocine/ ... is an agonist at the kappa & sigma opioid receptors & has a weak antagonist action at the mu receptor. ... Pentazocine has a more rapid onset & a shorter duration of action than morphine ... /Pentazocine hydrochloride; pentazocine lactate/ The pattern of CNS effects produced by pentazocine is generally similar to that of the morphine-like opioids, including analgesia, sedation, and respiratory depression. The analgesic effects of pentazocine are due to agonistic actions at kappa1-opioid receptors. Higher doses of pentazocine (60 to 90 mg) elicit dysphoric and psychotomimetic effects similar to those of nalorphine.

Pharmacodynamics

Pentazocine is a potent analgesic which when administered orally in a 50 mg dose appears equivalent in analgesic effect to 60 mg (1 grain) of codeine. Onset of significant analgesia usually occurs between 15 and 30 minutes after oral administration, and duration of action is usually three hours or longer. Onset and duration of action and the degree of pain relief are related both to dose and the severity of pretreatment pain. Pentazocine weakly antagonizes the analgesic effects of morphine and meperidine; in addition, it produces incomplete reversal of cardiovascular, respiratory, and behavioral depression induced by morphine and meperidine. Pentazocine has about 1/50 the antagonistic activity of nalorphine. It also has sedative activity.