PDR Health

MS Contin

What is MS Contin?

MS Contin (morphine sulfate extended-release tablets) is an opioid agonist supplied in 15 mg, 30 mg, 60 mg, 100 mg, and 200 mg tablet strengths for oral administration. The 15 mg and 30 mg tablets are scored so they can be divided into equal halves.

Morphine sulfate extended-release tablets are white to off-white, round, film coated tablets debossed with M on one side and 15, 30, 60, 100, or 200 on the other side of the tablet corresponding to the following strengths:

MS Contin tablets are designed to provide a controlled, continuous release of morphine over an extended period of time. MS Contin is indicated for the management of pain severe enough to require daily, around-the-clock, long-term opioid treatment and for which alternative treatment options are inadequate.

MS Contin

Side Effects

The most commonly reported side effects include:









Mechanism of Action

Morphine sulfate is a full opioid agonist with relative selectivity for the mu-opioid receptor, although it can bind to other opioid receptors at higher doses. These mu-binding sites are discretely distributed in the human brain and spinal cord and are involved in analgesia, reward, habituation, tolerance, and dependence. The precise mechanism of action of MS Contin is unknown, but like other opioids,MS Contin probably binds to mu receptors in the CNS and/or other structures that modulate pain perception and transmits inhibitory impulses through the descending pain pathways in the brain stem leading to increased pain threshold and analgesia.

Dosage and Administration

MS Contin is indicated for the management of pain severe enough to require daily, around-the-clock, long-term opioid treatment and for which alternative treatment options are inadequate.


Concomitant use of MS Contin with CYP3A4 inducers or discontinuation of a CYP3A4 inhibitor may result in lower plasma concentrations of morphine and potentially reduce efficacy or manifestations of opioid withdrawal.

MS Contin is metabolized by cytochrome P450 enzymes, primarily CYP3A4, to form the active metabolite, M3G, and inactive metabolites, M6G and normorphine. The metabolic pathways of morphine involve both phase 1 (oxidation) and phase 2 (conjugation) reactions.

CYP3A4 Inhibitors:

Concomitant use of MS Contin with strong or moderate CYP3A4 inhibitors may result in an increase in plasma concentrations of morphine which could enhance or prolong adverse reactions and may cause potentially fatal respiratory depression.

CYP2D6 Inhibitors:

Concomitant use of MS Contin with CYP2D6 inhibitors may result in increased plasma concentrations of Morphine.

Warnings and Precautions

MS Contin is contraindicated in patients with significant respiratory depression, acute or severe bronchial asthma in an unmonitored setting or in the absence of resuscitative equipment, known or suspected gastrointestinal obstruction, including paralytic ileus, and hypersensitivity (e.g., anaphylaxis) to morphine or other opioids.

This should be considered when prescribing or dispensing MS Contin in situations where the physician or pharmacist is concerned about an increased risk of misuse, abuse, or diversion.


Other long-acting opioids such as oxycodone, hydromorphone, and fentanyl may be suitable alternatives to MS Contin.

Long-term effects of opioids

The long-term effects of opioids can be both physically and psychologically damaging. Some of the most common physical effects include:

reduced testosterone levels

decreased libido


reduced sperm count


hormonal imbalances

muscle weakness


weight gain

The long-term psychological effects of opioids can be just as damaging, if not more so. Some of the most common psychological effects include:



mood swings





Is oxycodone more effective than MS Contin?

There is no definitive answer to this question as different people will respond differently to different medications. Some people may find that oxycodone is more effective than MS Contin, while others may find the reverse to be true. Ultimately, it is important to work with a healthcare professional to find the medication that is best for you.