Table 1.
Examples of drugs with very poor bioavailability with reported reasons.
| Drugs | Pharmacological Class | Bioavailability (%) | Reasons | References |
|---|---|---|---|---|
| Alendronate | Bisphosphonates | 0.59–0.78 | Poor solubility and absorption | [5,6,7] |
| Atorvastatin | Statins | 14 | P-gp and CYP450 activities | [8,9,10] |
| Bromocriptine | Dopamine receptor agonists | 5–10 | Extensive first-pass effect | [11,12,13] |
| Clodronate | Bisphosphonates | 1 | Poor solubility and absorption | [5,6,7] |
| Cytarabine | Antimetabolites | 20 | Intestinal and hepatic first-pass | [14] |
| Domperidone | D2 receptor antagonists | 15 | Gut and liver first-pass | [15] |
| Doxorubicin | Anthracycline antibiotics | 5 | Hepatic and intestinal metabolism | [16] |
| Budesonide | Corticosteroids | 11 | Hepatic first-pass effect | [17] |
| Etidronate | Bisphosphonates | 5 | Poor solubility and absorption | [6,7,13] |
| Felodipine | Calcium channel blockers | 15 | P-gp and CYP450 activities | [17] |
| Isradipine | Calcium channel blockers | 15 | P-gp and CYP450 activities | [18] |
| Fluvastatin | Statins | 20 | P-gp and CYP450 activities | [8,9,10] |
| Nimodipine | Calcium Channel blockers | 13 | P-gp and CYP450 activities | [19] |
| Hyoscine | Antispasmodics | 20 | Hepatic metabolism | [20] |
| Ketamine | Dissociative anesthetics | 20 | Hepatic and intestinal metabolism | [21] |
| Lovastatin | Statins | <5 | P-gp and CYP450 activities | [8,9,10] |
| Morphine | Opioids | 20–33 | Gut and liver first-pass | [22] |
| Pyridostigmine | Acetylcholinesterase inhibitors | 14 | Poor absorption | [23] |
| Naloxone | Opioid antagonists | 2–10 | Extensive first-pass but 90% absorption | [24] |
| Naltrexone | Opiate antagonists | 5–40 | First-pass, enterohepatic recycling | [10] |
| Pamidronate | Bisphosphonates | 1 | Poor solubility and absorption | [5,6,7] |
| Pravastatin | Statins | 17–34 | P-gp and CYP450 activities | [8,9,10] |
| Prochlorperazine | Phenothiazines | 20 | Intestinal and hepatic first-pass | [25] |
| Risedronate | Bisphosphonates | <1 | Poor solubility and absorption | [5,6,7] |
| Selegiline | Monoamine oxidase type B inhibitors | 20 | Extensive first-pass | [26] |
| Simvastatin | Statins | 5–48 | P-gp and CYP450 activities | [8,9,10] |
| Sumatriptan | Serotonin receptor agonists | 20 | Hepatic first-pass | [27] |
| Tacrine | Cholinesterase inhibitors | 10–30 | Hepatic first-pass | [28] |
| Terbutaline | Adrenergic receptor agonists | 9–21 | Extensive first-pass and poor absorption | [29] |
| Lidocaine | Local anesthetics | 3 | Hepatic first-pass effect | [30] |
| Tiludronate | Bisphosphonates | 6 | Poor solubility and absorption | [5,6,7] |