*Examples of drugs showing ceiling effect are :
- Loop diuretics (high ceiling diuretics)
- Ceiling effects for analgesia and respiratory depression are observed above 50 to 100 mg pentazocine. Pentazocine has opioid agonistic actions and weak opioid antagonistic activity. It is a type of opioid analgesic.
- Nalbuphine exhibits a ceiling effect such that increases in dosage beyond 30 mg produce no further respiratory depression. However, a ceiling effect for analgesia also is reached at this point.
Nalbuphine is related structurally to naloxone and oxymorphone. It is an agonist–antagonist opioid with a spectrum of effects that qualitatively resembles that of pentazocine; however, nalbuphine is a more potent antagonist at MU receptors and is less likely to produce dysphoric side effects than is pentazocine.
- Buprenorphine is a semisynthetic, highly lipophilic opioid derived from thebaine. It is 25 to 50 times more potent than morphine. This drug is also believed to show the ceiling effect. Patients receiving methadone or buprenorphine will not experience the ups and downs experienced while on heroin. Drug craving diminishes and may disappear. Buprenorphine, as a partial agonist, has a ceiling effect at about 16 mg of the sublingual tablet equaling no more than 60 mg methadone. If the patient has a higher level of physical dependence, methadone, a full agonist, must be used.
- The patient's ability to tolerate and absorb medicinal iron is a key factor in determining the rate of response to therapy. The small intestine regulates absorption, and with increasing doses of oral iron, limits the entry of iron into the bloodstream. This provides a natural ceiling on how much iron can be supplied by oral therapy.
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