PYRAMAX GRANULES FOR ORAL SUSPENSION

Indications

• Severe malaria caused by _Plasmodium falciparum_
• Uncomplicated malaria in combination with other antimalarial agents

Dosage

Adults: For adults, the typical dosing regimen is an initial dose of 2.4 mg/kg intravenously, followed by 1.2 mg/kg at 12 and 24 hours, with subsequent doses depending on clinical response

Mechanism of action

Artesunate is metabolized to dihydroartemisinin (DHA), which reacts with heme, generating free radicals that inhibit protein and nucleic acid synthesis in _Plasmodium_ parasites during all erythrocytic stages. This interaction with free radicals can lead to the alkylation of essential parasitic proteins, disrupting their normal function. Two primary theories explain its action: one suggests that artemisinins are activated by interaction with ferrous iron or reduced heme, producing reactive radicals that alkylate biomolecules; the other posits that the intact artemisinin binds to vital proteins in the parasite, leading to the formation of reactive oxygen species.

Pharmacodynamics

As an artemisinin derivative, artesunate is metabolized to dihydroartemisinin, which generates free radicals that inhibit the function of _Plasmodium_ parasites. It has a short duration of action due to its short half-life, and while it possesses a moderate therapeutic index, patients should be informed about potential post-treatment hemolytic anemia and hypersensitivity reactions.

Pharmacokinetics

Artesunate is rapidly absorbed and converted to DHA, which has a short half-life. The pharmacokinetics of artesunate can be influenced by factors such as the presence of food and other medications. It is primarily metabolized in the liver and excreted in urine, with a rapid onset of action that makes it suitable for emergency treatment of severe malaria.

Adverse effects

• Hypersensitivity reactions
• Hemolytic anemia
• Gastrointestinal disturbances
• Headache
• Dizziness
• Fatigue

Precautions

• Caution in patients with a history of hypersensitivity to artemisinin derivatives
• Monitor for signs of hemolytic anemia
• Use with caution in patients with liver impairment

Pregnancy

Artesunate is classified as category C. The risks versus benefits should be assessed before use in pregnant women.

Breast-feeding

It is not known if artesunate is excreted in human milk. Caution is advised when administering to breastfeeding women.

Storage

Store at room temperature (15-30 degrees Celsius) in a tightly closed container, protected from light and moisture.

Formulations

• Injectable solution
• Oral tablets

Indications

• Uncomplicated malaria
• Plasmodium falciparum malaria
• Plasmodium vivax malaria

Dosage

Children: Refer to specific guidelines or consult local clinical protocols for appropriate dosing, as no specific paediatric dosage is provided.

Adults: Refer to specific guidelines or consult local clinical protocols for appropriate dosing, as no specific adult dosage is provided.

Mechanism of action

Pyronaridine acts by inhibiting the heme polymerization process in Plasmodium species. This leads to the accumulation of toxic heme, causing damage to the parasite's cell membranes and ultimately resulting in cell death. The drug may also interfere with mitochondrial function and disrupt energy metabolism within the parasite.

Pharmacodynamics

Pyronaridine demonstrates a dose-dependent relationship with its antimalarial activity. It has shown to have a rapid onset of action, with its effectiveness being influenced by the stage of the parasite's lifecycle. The drug is particularly effective against the asexual stages of the parasite but has no effect on the liver stage.

Pharmacokinetics

After oral administration, pyronaridine is rapidly absorbed, with peak plasma concentrations occurring within a few hours. It is primarily metabolized in the liver, and the half-life is influenced by individual metabolic rates and potential interactions with other medications. The drug is excreted mainly via urine and feces. Its pharmacokinetic profile supports once-daily dosing in most cases.

Pregnancy

There are no well-controlled studies in pregnant women. Use only if clearly needed and the benefits outweigh the risks.

Breast-feeding

It is unknown whether pyronaridine is excreted in human milk. Exercise caution when administering to nursing mothers.

Storage

Store at room temperature, away from light and moisture. Keep out of reach of children.

Dosage

Children: Refer to relevant safety guidelines, as specific dosing information for clinical use is not provided in the BNF.

Adults: Refer to relevant safety guidelines, as specific dosing information for clinical use is not provided in the BNF.

Mechanism of action

Tetrachloride is a non-polar solvent that dissolves a wide range of organic compounds. It disrupts cellular membranes and can interfere with metabolic processes by forming reactive intermediates, leading to cellular damage. The mechanism may also involve the induction of oxidative stress and mitochondrial dysfunction.

Pharmacodynamics

The pharmacodynamic effects of tetrachloride are primarily linked to its role as a solvent and its cytotoxic properties. It can cause cellular damage, particularly in the liver, through lipid peroxidation and disruption of cellular integrity. Its effects may vary based on exposure duration, concentration, and route of administration, leading to acute or chronic toxicity.

Pharmacokinetics

Tetrachloride is absorbed through the respiratory tract, gastrointestinal tract, and skin. Once in the bloodstream, it distributes widely throughout body tissues, particularly in adipose tissue and the liver, where it undergoes biotransformation via cytochrome P450 enzymes. The elimination half-life can vary, but it is primarily excreted through the urine as metabolites. Accumulation may occur with prolonged exposure, leading to increased toxicity.

Pregnancy

There is insufficient data on the safety of tetrachloride in pregnancy. Caution is advised.

Breast-feeding

Caution is advised as the effects on nursing infants are not well-studied.

Storage

Store in a cool, dry place away from direct sunlight and heat sources. Keep in tightly closed containers.

Dosage

Children: Refer to specific drug information for paediatric dosing guidelines, as this will depend on the active compound and its therapeutic use.

Adults: Refer to specific drug information for adult dosing guidelines, as this will depend on the active compound and its therapeutic use.

Mechanism of action

The mechanism of action will depend on the specific active compound that is in the tetrahydrate form. Generally, tetrahydrates can improve the bioavailability of a drug by facilitating its dissolution in bodily fluids, which can enhance absorption in the gastrointestinal tract.

Pharmacodynamics

Pharmacodynamics will vary based on the specific drug in the tetrahydrate form. However, it generally involves the interaction of the drug with specific receptors or enzymes in the body, influencing physiological and biochemical processes. Tetrahydrate forms may affect the pharmacokinetics of the drug, altering its efficacy and safety profile.

Pharmacokinetics

Pharmacokinetics of a tetrahydrate form will depend on the parent compound. Typically, factors such as absorption, distribution, metabolism, and excretion can be influenced by the hydration state of the drug. Hydrates may have different solubility and stability profiles, which can impact the rate and extent of drug absorption.

Dosage

Children: Refer to specific guidelines or clinical recommendations for appropriate dosing.

Adults: Refer to specific guidelines or clinical recommendations for appropriate dosing.

Mechanism of action

Tetraphosphate acts as a phosphate donor in biochemical reactions, participating in the transfer of phosphate groups to other molecules. This mechanism is essential in the regulation of metabolic pathways and energy production within cells.

Pharmacodynamics

As a polyphosphate, tetraphosphate influences cellular processes by modulating the availability of phosphate. The compound is involved in energy metabolism, particularly in the synthesis and hydrolysis of ATP, and may also impact nucleic acid metabolism and signaling pathways that rely on phosphate.

Pharmacokinetics

The pharmacokinetics of tetraphosphate are not well-documented; however, it is generally assumed that, like other phosphate compounds, it may be absorbed and utilized in various tissues, with renal excretion being a likely route for elimination.

Indications

• pH stabilization in pharmaceutical formulations
• solubilization of poorly soluble drugs
• buffering agent in injectable preparations

Dosage

Children: Refer to specific product guidelines for paediatric dosing as it may vary based on formulation.

Adults: Refer to specific product guidelines for adult dosing as it may vary based on formulation.

Mechanism of action

Tetrasodium functions primarily as a buffering agent, helping to maintain the pH of pharmaceutical preparations. This stabilization is crucial in ensuring the solubility and bioavailability of active pharmaceutical ingredients, thereby enhancing their therapeutic effects.

Pharmacodynamics

The pharmacodynamic properties of tetrasodium relate to its ability to modulate pH levels in a solution. By maintaining optimal pH conditions, tetrasodium aids in preserving the stability and efficacy of various drugs, improving their overall therapeutic action.

Pharmacokinetics

Tetrasodium is generally not absorbed systemically when used in pharmaceutical formulations, as its primary role is localized within the preparation. Its pharmacokinetic profile is largely influenced by its solubility and stability in solution, which can affect the release and absorption of the active ingredients it is combined with.

Mechanism of action

Artesunate is metabolized to the active DHA. the endoperoxide bridge of DHA reacts with heme, generating free radicals which inhibit protein and nucleic acid synthesis of the _Plasmodium_ parasites during all erythrocytic stages. Reactions with these free radicals can also lead to alkylation of parasitic proteins such as a calcium adenosine triphosphatase and EXP1, a glutathione S-transferase. Two theories have been put forward for the mode of antimalarial action of the artemisinin antimalarials, in accodance with the known properties of peroxides with medicinal activity. The first assumes that the artemisinins must be activated by contact with either reduced haem (ferrous haem, Fe(ll)PPIX) or non-haem ferrous iron (exogenous iron), causing cleavage of the peroxide to generate oxygen-centered radicals (alkoxy radicals') which are the presumed to be converted into carbon-centered radicals by transfer of proximate hydrogen atoms from the periphery of the peroxide molecule. These carbon-centered radicals are then thought to alkylate sensitive, yet unspecified, biomolecules in the parasite. A second theory argues for a process in which the intact artemisinin binds to a site within a vital protein in the parasite. The act of binding causes the peroxide to be converted to hydroperoxide or similar open peroxide, which in accordance with known properties of such compounds, generates one or more active chemical entities, either oxidizing agents or oxygen transfer agents per se, or oxygen-centered free radicals. This would be associated with the binding process. In such a way, the artemisinins might act as (irreversibile) inhibitors. Iron may, or may not, be associated with the activation process. No specific biological target in the parasite has yet been identified in support of this theory, but it may be membrane-bound proteins. Artesunate is a water soluble derivative of artemisinin, an antimalarial compound isolated from the Chinese herb Qinghao (Artemisia annua). Artesunate is rapidly metabolized to dihydroartemisinin (DHA) in the body. Chemically, artesunate, and its active metabolite, DHA, are sesquiterpene lactones with a trioxane ring containing a peroxide bridge. The peroxide bridge appears to be essential for the antimalarial activity of artesunate. Structure-activity relationship studies show that the deoxy derivative of DHA (that lack the peroxide bridge) was 277-fold less active than DHA. The activity of deoxyartesunate was not measured. Deoxy derivatives of other artemisinin analogs were 10- to 1000-fold less active compared to the parent compounds. Artesunate increases superoxide anion production and lipid peroxidation in falciparum-infected erythrocytes in vitro. However, artesunate does not suppress the activity of antioxidant enzymes (superoxide dismutase, catalase, glutathione reductase, and glutathione peroxidase) in infected or uninfected erythrocytes. Erythrocytes infected with the ring or trophozoite forms in vitro accumulate 100- and 180- fold higher concentrations of DHA (12 nM ie, 3.40 ng/mL), respectively, compared to uninfected erythrocytes. These experiments were performed in a medium containing 10% human serum. The relevance of these findings to the uptake in vivo is unclear. The precise mechanism by which artesunate exhibits antiplasmodial activity is not understood. A 2025 systematic review notes Artesunate's pharmacological activities (antimalarial, antiparasite,antitumor, antivirus, antiinflammation, and antibacterial),and that it is a highly effective antimalarial agent with the potential to induce organ toxicity under certain conditions. The authors note that mechanisms of Artesunate-induced toxicity include oxidative stress, inflammation, and apoptotic signaling patthhways.They also note that Artesunate ameliorates MASH (Metabolic Dysfunction-Associated Steatohepatitis) by reducing inflammation and lipid accumulation by regulating NLRP3 inflammasome and reducing lipid accumulation (SREBP-1c, FAS).

Pharmacodynamics

Artesunate is an artemisinin derivative that is metabolized to DHA, which generates free radicals to inhibit normal function of _Plasmodium_ parasites. It has a short duration of action due to its short half life, and a moderate therapeutic index. Patients should be counselled regarding the risk of post treatment hemolytic anemia and hypersenstivity.