PROSTIN-F2-ALPHA 5MG/ML INJECTION

Indications

• Induction of labor
• Medical abortion
• Management of postpartum hemorrhage
• Termination of pregnancy

Dosage

Children: Refer to BNF for Children for appropriate dosing information based on the child's condition and age.

Adults: Refer to BNF for specific dosing guidelines, as doses may vary based on indication and clinical judgment.

Mechanism of action

Dinoprost exerts its effects by binding to specific prostaglandin receptors, leading to an increase in intracellular calcium levels, which subsequently stimulates uterine contractions. It can also alter cyclic AMP accumulation, demonstrating diverse responses that may vary by species. The drug promotes vasodilation in certain vascular beds while contracting smooth muscle in others. Dinoprost effectively reduces progesterone output, causing the regression of the corpus luteum, which interrupts early pregnancy.

Pharmacodynamics

Dinoprost has a significant impact on the uterine smooth muscle, inducing contractions that facilitate abortion or labor. It also plays a role in vasodilation and vascular smooth muscle contraction, depending on the site of action. The drug's effects are additive when used in combination with oxytocin, potentially enhancing uterine activity. The pharmacological actions of dinoprost are mediated through its interactions with eicosanoid pathways, influencing various physiological responses.

Pharmacokinetics

Dinoprost is rapidly absorbed and metabolized, with its pharmacokinetic profile characterized by a short half-life. The drug is primarily eliminated via metabolic pathways, including conversion to various inactive metabolites. Its distribution in the body is influenced by the lipid solubility of prostaglandins, with significant binding to tissues, particularly those involved in reproductive functions. The onset of action is usually quick, with effects observable shortly after administration.

Pregnancy

Dinoprost is contraindicated in pregnancy as it can induce uterine contractions and lead to abortion.

Breast-feeding

There is limited data on the excretion of dinoprost in human milk. Caution should be exercised when administering to breastfeeding women.

Storage

Store at room temperature, protected from light. Do not freeze.

Formulations

• Injectable solution

Indications

• Metabolic acidosis
• Acute kidney injury
• Cardiac arrest
• Severe lactic acidosis

Dosage

Children: Refer to BNF for Children for appropriate dosing in paediatric patients.

Adults: Refer to BNF for specific dosing guidelines based on clinical condition and severity of acidosis.

Mechanism of action

Tromethamine functions as a proton acceptor, interacting with hydrogen ions and their associated acid anions. It combines with lactic, pyruvic, and other metabolic acids, as well as carbonic acid, facilitating their excretion in urine. At physiological pH, tromethamine exists in both ionized and un-ionized forms, with the latter capable of penetrating cell membranes to neutralize intracellular acids. By reducing hydrogen ion concentration, tromethamine alters the bicarbonate:carbonic acid buffer system, increasing bicarbonate levels while decreasing carbon dioxide tension, which may lead to hypoventilation.

Pharmacodynamics

As an alkalinizing agent, tromethamine increases bicarbonate concentrations in the blood, thereby helping to correct metabolic acidosis. Its ability to act as a weak osmotic diuretic contributes to increased urine output and the excretion of electrolytes. This dual action is beneficial in managing conditions characterized by acid-base imbalances.

Pharmacokinetics

After intravenous administration, tromethamine is rapidly distributed in the body. It is primarily excreted unchanged in the urine, with its alkalinizing effects lasting until the body's regulatory mechanisms restore acid-base balance. The pharmacokinetics are influenced by the ionization state of the drug, which varies with pH levels.

Adverse effects

• Hypoventilation
• Hypoxia
• Fluid and electrolyte imbalances
• Metabolic alkalosis
• Nausea
• Vomiting

Precautions

• Use with caution in patients with respiratory depression
• Monitor patients for signs of fluid overload
• Assess electrolyte levels regularly during treatment

Pregnancy

There are no adequate and well-controlled studies in pregnant women. Tromethamine should be used during pregnancy only if the potential benefit justifies the potential risk to the fetus.

Breast-feeding

It is not known whether tromethamine is excreted in human milk. Caution should be exercised when administering tromethamine to a nursing mother.

Storage

Store at room temperature, away from light and moisture. Do not freeze.

Formulations

• Injection solution

Mechanism of action

...THERE IS NO SINGLE PROSTAGLANDIN RECEPTOR. ... IT IS POSSIBLE TO DEMONSTRATE CALCIUM DEPENDENCE OF DIVERSE RESPONSES TO PROSTAGLANDINS & TO OBSERVE ALTERED CALCIUM FLUXES. ...PROSTAGLANDINS MAY EITHER STIMULATE OR INHIBIT ACCUM OF CYCLIC AMP. /PROSTAGLANDINS/ RESPONSES TO PROSTAGLANDIN F2ALPHA SHOW SPECIES VARIATION, BUT VASODILATATION HAS BEEN OBSERVED FOLLOWING INJECTION INTO HUMAN BRACHIAL ARTERY OF PGF2ALPHA... SUPERFICIAL VEINS OF HAND ARE CONTRACTED BY PFG2ALPHA... PROMPT SUBSIDENCE OF PROGESTERONE OUTPUT & REGRESSION OF CORPUS LUTEUM FOLLOWS PARENTERAL INJECTION OF PROSTAGLANDIN F2ALPHA... THIS EFFECT INTERRUPTS EARLY PREGNANCY, WHICH IS DEPENDENT ON LUTEAL RATHER THAN PLACENTAL PROGESTERONE. OXYTOCIN & PROSTAGLANDINS AFFECT UTERINE SMOOTH MUSCLES BY DIFFERENT MECHANISMS, & THEIR EFFECTS ARE ADDITIVE. POSSIBLE ADVANTAGES OF THEIR COMBINED USE ARE BEING EXPLORED. /PROSTAGLANDINS/

Mechanism of action

Tromethamine is an alkalinizing agent which acts as a proton (hydrogen ion) acceptor. Tromethamine is a weak base; following IV injection, it attracts and combines with hydrogen ions and their associated acid anions and the resulting salts are excreted in urine. Tromethamine can combine with lactic, pyruvic, and other metabolic acids and with carbonic acid. ... At pH 7.4, approximately 70% of the tromethamine present in plasma is in the ionized (protonated) form; if pH is decreased from pH 7.4, the ionized fraction of the drug is increased. In contrast to the ionized fraction of tromethamine, which upon administration reacts only with acid in the extracellular fluids, the fraction of the dose which remains un-ionized at physiologic pH is thought to be capable of penetrating the cell membrane to combine with intracellular acid. Since administration of tromethamine reduces hydrogen ion concentration, there is a decrease in proton donor and an increase in proton acceptor concentrations in body buffers. In the bicarbonate:carbonic acid buffer, the concentration of dissolved carbon dioxide is decreased (at least until regulatory mechanisms compensate) and the concentration of bicarbonate is increased. The reduction of carbon dioxide tension removes a potent stimulus to breathing and may result in hypoventilation and hypoxia. Tromethamine ... acts as a weak, osmotic diuretic, increasing the flow of alkaline urine containing increased amounts of electrolytes. By removing protons from hydronium ions, ionization of carbonic acid is shifted so as to decrease pCO2 and to increase bicarbonate. Excess bicarbonate is then gradually excreted in kidney. /Tromethamine is an/ especially useful way to manage excessively high pCO2 in respiratory acidosis...