Morphine dosages

Morphine is also hepatically metabolized to normorphine by the cytochrome P-450 enzymes GYP 3A4 and CYP2C8. Small amounts of codeine and hydromorphone are also produced, which is not clinically significant but can cause false positive urine drug tests for these substances. Morphine dosage should be reduced in patients with impaired renal function. 

Salem and Galan have developed a new method for determining the amount of morphine hydrochloride in tablets. Results, in milligrams, for several tablets containing different nominal dosages follow... 

A patient is prescribed oral morphine 12 mg. The dosage available is 10 mg/mL. The nurse administers... 

Blasig, J. Hen, A. Reinhold, K. and Zieglgansberger, S. Development of physical dependence on morphine in respect to time and dosage and quantification of the precipitated withdrawal syndrome in rats. Psychopharmacologia 33 19-38, 1973. 

Rectal Administration. The administration of drugs by a solid rectal dosage form (i.e., suppositories) results in a wide variability in the rate and extent of absorption in children [79]. This fact, coupled with the inflexibility of a fixed dose, makes this a route that should not be promoted for pediatric patients. At least one death involving a 7-month-old infant can be directly attributed to the use of solid rectal dosage form of a therapeutic dose of morphine [80]. 

Causes of adverse effects over-dosage (A). The drug is administered in a higher dose than is required for the principal effect this directly or indirectly affects other body functions. For instances, morphine (p. 210), given in the appropriate dose, affords excellent pain relief by influencing nociceptive pathways in the CNS. In excessive doses, it inhibits the respiratory center and makes apnea imminent The dose dependence of both effects can be graphed in the form of dose-response curves (DRC). The distance between both DRCs indicates the difference between the therapeutic and toxic doses. This margin of safety indicates the risk of toxicity when standard doses are exceeded. 

When the oral route is unavailable opioids may be administered by continuous infusion (pump) and when appropriate under control by the patient - advantage constant therapeutic plasma level disadvantage indwelling catheter. When constipation becomes intolerable morphin can be applied near the spinal cord permitting strong analgesic effect at much lower total dosage. 

The following equianalgesic dosing table is based on parenteral morphine 10 mg. Dosage adjustments may be needed if the elimination half-life of the new opioid... 

Dose titration - Base appropriate dosage increments on the daily dose of supplementary opioids, using the ratio of 45 mg/24 h of oral morphine to a 12.5 mcg/h increase in transdermal fentanyl dose. 

The MS Contin 200 mg tablet is for use only in opioid-tolerant patients requiring daily morphine-equivalent dosages of 400 mg or more. Reserve this strength for patients who have already been titrated to a stable analgesic regimen using lower... 

Concentrate oral solution - Administer with caution since the solution is a highly concentrated solution of morphine. Error in dosage or confusion between milligrams of morphine and milliliters of solution may cause significant overdosage. Dosing instructions should be clearly prescribed in milligrams of morphine and milliliters of solution. Verify correct dose and... 

Seizures Seizures may be aggravated or may occur in individuals with or without a history of convulsive disorders if dosage is substantially increased above recommended levels because of tolerance. Observe patients with known seizure disorders closely for hydromorphone-, meperidine-, morphine-, or tramadol-induced seizure activity. 

Respiratory depression At the usual adult dose of 10 mg/70 kg, nalbuphine causes respiratory depression approximately equal to that produced by equal doses of morphine. However, nalbuphine exhibits a ceiling effect increases in dosage beyond 30 mg produce no further respiratory depression. Respiratory depression induced by nalbuphine can be reversed by naloxone. Administer nalbuphine with caution at low doses to patients with impaired respiration (eg, from other medication, uremia, bronchial asthma, severe infection, cyanosis, or respiratory obstructions). 

The opioids generally have a high level of safety when used in therapeutic dosages. However, there are several notable exceptions. Morphine and other opioids are contraindicated in patients with hypersensitivity reactions to the opioids. In addition, morphine should not be used in patients with acute bronchial asthma and should... 

Fentanyl is 80 to 100 times as potent as morphine. Sufentanil (Sufenta) is 500- to 1,000-fold more potent than morphine, while alfentanil (Alfenta) is approximately 20 times more potent than morphine. Their onset of action is usually less than 20 minutes after administration. Dosage is determined by the lean body mass of the patient, since the drugs are lipophilic and tend to get trapped in body fat, which acts as a reservoir, prolonging their half-life. In addition, redistribution of the drugs from the brain to fat stores leads to a rapid offset of action. Droperidol, a neuroleptic agent, is generally administered in combination with fentanyl for IV anesthesia. 

Apomorphine, a derivative of morphine, acts directly on the CTZ. It also is more effective if water is first administered before oral or subcutaneous dosing. Excessive dosage may cause respiratory depression and circulatory collapse. Opioid antagonists such as naloxone usually reverse the depressant actions of apomorphine. Because of the possibility of respiratory depression, apomorphine is infrequently used as an emetic. 

Contraindications Hypersensitivity to morphine sulfate or any component of the formulation, increased intracranial pressure, severe respiratory depression, severe hepatic or renal insufficiency, pregnancy (prolonged use or high dosages near term)... 

---